As noted in my previous newsletter, NC RFWG agencies are proactively conducting self-assessments of their needs and processes to identify challenges and opportunities early, enabling a smooth transition and sustained operational efficiency. The working group meets monthly to review progress on activities.
One key task of the working group was to develop a short online questionnaire. The goal was to open a dialogue with geospatial professionals and better understand their readiness for the upcoming modernization of the National Spatial Reference System (NSRS).
The questionnaire was designed to address the following key questions:
Are you prepared to implement the new NSRS once the National Geodetic Survey (NGS) officially adopts it?
Do you have the necessary tools and resources in place to ensure a smooth transition?
Has your organization established a timeline for transitioning to the modernized NSRS?
What concerns do you have regarding the transition to the new NSRS?
The section titled “Introduction of North Carolina Questionnaire” explains the purpose and background of the survey, while the section titled “North Carolina Online Questions” presents the list of questions included in the questionnaire.
Introduction of the North Carolina Questionnaire
This questionnaire seeks stakeholder input on the upcoming modernization of the National Spatial Reference System (NSRS). Your feedback is welcome on the proposed questions, as well as any concerns about the datum transition, tools (such as updated NCAT, OPUS, and SPCS2022), data transformation strategies, workflow impacts, and preparation needs.
The National Geodetic Survey (NGS) is replacing the North American Datum of 1983 and the North American Vertical Datum of 1988 with new plate-fixed terrestrial reference frames (NATRF2022, PATRF2022, CATRF2022, and MATRF2022) tied to the International Terrestrial Reference Frame 2020, along with the new vertical datum, the North American-Pacific Geopotential Datum of 2022.
In spring 2027, new horizontal and vertical datums will be implemented:
Horizontal
North American Terrestrial Reference Frame (NATRF2022)
Replaces the North American Datum of 1983 (2011)
Vertical
North American-Pacific Geopotential Datum of 2022 (NAPGD2022)
Replaces North American Vertical Datum of 1988
Units
14B NCAC 03 .0602 REQUIRED FOOT CONVERSION
North Carolina Online Questions
The section titled “Results of North Carolina Online Questionnaire” summarizes the survey responses collected as of April 27, 2026.
[Note: NCPMA refers to the North Carolina Property Mappers Association, and LGUC refers to the North Carolina Local Government Committee.]
Results of the North Carolina Online Questionnaire
(April 27, 2026)
This questionnaire solicited input from the North Carolina Property Mappers Association (NC PMA), the North Carolina Geographic Information Coordinating Council (GICC), and the North Carolina Local Government Committee (LGC). Although focused on North Carolina, the results may benefit other working groups. The NC working group is reviewing all feedback—especially regarding the Spring 2027 datum change—and will develop materials to address it.
In addition to the questionnaire, the working group prepared a short guidance document on the new reference frames for local governments and state agencies. It outlines how to prepare for the 2027 datum change and covers:
Preliminary steps for transitioning when NGS and North Carolina officially adopt the new datums in 2027.
Actions users can take now to ready NSRS‑referenced data for the modernized NSRS and the shift from U.S. Survey Foot/International Foot.
Estimated coordinate changes with the 2027 adoption of:
North American Terrestrial Reference Frame (NATRF2022)
North American-Pacific Geopotential Datum of 2022 (NAPGD2022)
New national geoid model (Geoid2022)
North Carolina State Plane Coordinate System of 2022 (SPCS2022)
Current NC statewide digital orthoimagery acquisition cycle and statewide lidar collection schedule.
How the NC CORS and Real-Time Network (RTN) will support the modernized NSRS.
Web links to more detailed resources.
The working group is developing a case study on preparing a FEMA Elevation Certificate using the modernized NSRS (NATRF2022 and NAPGD2022). It will be featured in upcoming newsletters. The North Carolina Geodetic Survey will host the materials on its website, and I’ll share the public link once it’s available.
In my January 2026 GPS World newsletter, I noted that the National Geodetic Survey (NGS) convened the Federal Geodetic Control Subcommittee (FGCS) meeting with federal geospatial agencies to boost awareness and align efforts on National Spatial Reference System (NSRS) Modernization government-wide. Key steps include cultivating internal champions to champion the initiative, distilling complex topics for clear leadership briefings, and bringing together agencies, partners, and industry to collaboratively shape solutions. I also highlighted that on Feb. 17-18, NGS staff would be participating in Geo Week 2026 in Denver to engage geospatial product and service users and further coordinate on the modernization. NGS gave several presentations during GeoWeek that addressed many of my questions on the new modernized NSRS. This newsletter will highlight some of NGS’s presentations.
First, a special shout-out to my dear friend and former colleague, Juliana Blackwell, retired Director of the National Geodetic Survey. NOAA’s Table Mountain Gravity Observatory in Boulder, Colorado — long known for its absolute gravity work — has been officially renamed the J. P. Blackwell Gravity Observatory. This well-earned tribute honors her outstanding dedication and visionary leadership at NGS. Congratulations, Juliana!
J. P. Blackwell Gravity Observatory. (Photo: NGS)J. P. Blackwell Gravity Observatory. (Photo: NGS)J. P. Blackwell Gravity Observatory. (Photo: NGS)
NGS employees participated in the following sessions and meetings during GeoWeek 2026:
ASPRS NSRS Modernization Working Group Meeting
NSRS Modernization — The Latest Technical Updates
Preparing to Put the Modernized National Spatial Reference System into Practice
Roundtable — NSRS Modernization and Professional Societies
As President of the American Association for Geodetic Surveying (AAGS), I participated in the session titled “Roundtable – NSRS Modernization and Professional Societies.” Dana J Caccamise II, NGS regional geodetic advisor, opened our session by describing the NGS Modernization Engagement Plan and Progress. As I mentioned last month, Dana should get an award for the material he has prepared and for his work assisting agencies and professional organizations in preparing for the new NSRS. I highlighted Caccamise’s work in my October 2025 GPS World newsletter.
All the NGS sessions provided the latest information on activities associated with NGS’s NSRS Modernization. Here are the specific questions I had going into the session, along with the clear answers provided by NGS personnel during their presentations and the follow-up Q&A:
What NGS products and services will be available when federal agencies officially adopt the new NSRS?
When the modernized NSRS is officially adopted (following FGCS approval and the transition to it becoming “the NSRS”), NGS will make available a full suite of updated tools, data access points, and services built around the new reference frames (e.g., NATRF2022 and variants), the North American-Pacific Geopotential Datum of 2022 (NAPGD2022), the State Plane Coordinate System of 2022 (SPCS2022), and associated geopotential models like GEOID2022. Key products expected to be operational and official include:
NCAT
NGS Maps
Geodetic Station Page
CORS
Geodetic Mark Page
Passive Marks
OPUS–Static 5.2
OPUS-Share
What NGS products and services will NOT be available when federal agencies officially adopt the new NSRS?
Upon official adoption of the modernized NSRS — after FGCS approval and the shift to the new system becoming “the NSRS” — several current products and services will no longer be part of the official modernized NSRS or will be discontinued in their present form. Key items not included or no longer supported in the modernized NSRS release include:
OPUS Projects 5 will not be supported
OPUS-Rapid Static (OPUS-RS) will not be supported (modernized OPUS-Static 5.2 is expected to handle a broader range of observations)
OPUS 6.0 and OPUS 6.1 will not be available
What GNSS data will be included in the first iteration of the computation of Reference Epoch Coordinates (REC) for marks?
At Geo Week 2026, NGS stated that its plans include providing Reference Epoch Coordinates (RECs) for certain legacy GNSS projects. Specifically, this includes:
GPS projects that were originally processed and published under the NAD 83 (2011) realization, and
Other GNSS projects will be officially published by NGS through the end of 2025\
After the first iteration of Reference Epoch Coordinates, is NGS planning to perform future adjustments to determine REC and SEC of new marks? If so, what process will be used to establish RECs on new marks?
Yes, NGS plans include performing future adjustments to compute Reference Epoch Coordinates (REC) for new marks. However, at this time, no final decision has been made on how often this will be performed.
Has NGS changed how users need to submit data to incorporate leveling data into NAPDG2022?
Yes, NGS has introduced changes to better integrate leveling data (differential height differences) into the modernized NSRS for computing orthometric Reference Epoch Coordinates (RECs) in NAPGD2022 (epoch 2020.00).
As documented in Blueprint Document 3, when performing leveling projects, users will also be required to occupy a number of primary marks with GNSS.
OPUS 6.1 is built for future expansion to support other geodetic measurements (classical, leveling)-no timeframe was given for this.
Is NGS planning to officially adopt the new NSRS before users can submit data to NGS for technical review and publication in the NGS database?
Yes, that is what NGS is saying at this moment (February 2026). OPUS Project 5 will not be supported and OPUS 6.1 will not be operational when the new NSRS is officially adopted.NGS is working on the OPUS 6 application and is trying to “minimize any gap in service.”
Is NGS recommending using the OPUS-Share utility until users can submit data to NGS for technical review and publication in NGS database?
Yes, that is what NGS is recommending at this moment (February 2026).
OPUS-Projects 5 will not be included in the modernized NSRS. Instead, NGS will focus on both developing an improved software suite for OPUS, known as OPUS 6.0 and OPUS 6.1, and minimizing any gap in service in which the current OPUS-Projects functionality is not available for users to organize, process, adjust, and submit high-accuracy GPS surveys for use by NGS in expanding and improving the NSRS. As noted above, OPUS-Share will remain available as a means to submit data to NGS.
When will OPUS 6.1 be available for users to submit data to NGS for technical review and publication in NGS database? Is it weeks away, months away, or years away?
NGS has not announced an official completion or release date for OPUS 6.0 and OPUS 6.1. However, they have indicated that active development is underway on this enhanced OPUS tool suite. It’s not imminent— meaning not expected within several months—but it’s also not a distant, multi-year project.
NGS is working on the application and is trying to “minimize any gap in service.”
“OPUS-Projects 5 will not be included in the modernized NSRS. Instead, NGS will focus on both developing an improved software suite for OPUS, known as OPUS 6, and minimizing any gap in service in which the current OPUS-Projects functionality is not available for users to organize, process, adjust, and submit high-accuracy GPS surveys for use by NGS in expanding and improving the NSRS. As noted above, OPUS-Share will remain available as a means to submit data to NGS.”
What’s the cut-off date for users to submit projects via OPUS Project 5 so the data can be part of future computations of RECs?
Current OPUS-Projects 5 is going to be supported until adoption of the new NSRS, with a deadline announced at least 6 months in advance.
“Note: the current OPUS Projects 5 software will be supported until the modernized system is adopted, and a deadline for OPUS-Projects users to submit their surveys for publication will be announced with at least six months’ notice.”
In the session “NSRS Modernization – The Latest Technical Updates,” the National Geodetic Survey (NGS) presented slides detailing the status and upcoming tasks for the modernized National Spatial Reference System (NSRS). Key highlights from the presentation are summarized below.
106th Wyoming Engineering and Surveying (WES) Society Conference – February 5, 2026 – Brian Shaw
2026 GeoWeek – Modernized Tools – February 17, 2026 – Brian Shaw
2026 GeoWeek – Updates to OPUS for Accessing the Modernized NSRS – February 17, 2026 – Dan Gillins
During Dru Smith’s presentation, he mentioned what will be included in the first iteration of the computation of Reference Epoch Coordinates (REC) for marks. The slide states that more than 150,000 geometric (XYZ) coordinates and 1 million geopotential coordinates (that is, orthometric heights) will get reference epoch coordinates (REC), epoch 2020.00. These will include data from NGS Integrated Database and from the OPUS Share database.
First Reference Epoch Coordinates (REC). (Presented at GeoWeek 2026)First Reference Epoch Coordinates (REC). (Presented at 106th WES Society Conference)
In the GeoWeek 2026 presentation by Seth Pollack (from NOAA’s National Geodetic Survey), a slide outlined the NSRS modernization timeline.
As detailed in the slide and consistent with NGS’s official rollout plan:
Beta products are currently being released incrementally on the beta site for public testing and feedback. This phased rollout began with initial beta releases in 2025 (following alpha in 2024) and continues through 2026, covering key components such as NAPGD2022, GEOID2022, SPCS2022, enhanced NCAT transformation tools, OPUS-Static updates, and forthcoming Data Delivery System features.
Each beta component, once released, undergoes public testing and stakeholder feedback, with overall testing continuing for at least 6 months after the final component is made available on the beta site.
Following sufficient testing—once all components appear stable and NGS has incorporated feedback—the Federal Geodetic Control Subcommittee (FGCS) will vote to recommend approval of the modernized NSRS. This vote is anticipated in late 2026 or early 2027.
Upon FGCS approval (and subsequent Federal Geographic Data Committee (FGDC) endorsement), NGS will probably publish a Federal Register Notice announcing the adoption. At that point, the modernized NSRS becomes the official National Spatial Reference System, replacing the legacy system (NAD 83 realizations, NAVD 88, etc.).
While earlier NGS documentation targeted adoption likely in mid-to-late 2026 (post-FGCS vote), recent updates from GeoWeek 2026 sessions and related reports indicate the full official adoption and transition may extend into the first part of 2027, accounting for final testing, FGCS/FGDC processes, Federal Register steps, and a smooth handover to avoid disruptions.
The current NSRS remains official throughout this period. Users are encouraged to test beta products now and provide feedback to help refine the system.
NSRS Modernization Timeline. (Presented at GeoWeek 2026)
Brian Shaw, NGS’s expert on GIS products and services, presented key updates on how users will access geodetic data in the modernized National Spatial Reference System (NSRS).
He emphasized the introduction of a revamped Data Delivery System (DDS), which includes:
Geodetic Mark Pages — for passive marks. These replace the current ASCII-text datasheets with modernized, user-friendly pages featuring updated Reference Epoch Coordinates (RECs), integrated photos, graphics, maps, project details, and easier navigation.
Geodetic Station Pages — for active stations like those in the NOAA CORS Network (NCN). These provide updated versions of existing CORS pages, including modernized coordinate functions (e.g., Coordinate Functions or time-dependent positioning info) aligned with the new reference frames (NATRF2022, etc.).
Additionally, Shaw highlighted a new interface for the NGS Map (the interactive web map application), serving as an enhanced landing page within the DDS. This updated “NGS Map” (replacing or evolving the current version at https://noaa.maps.arcgis.com/apps/webappviewer/index.html?id=190385f9aadb4cf1b0dd8759893032db ) will provide better access to geodetic control data, CORS stations, and other layers, improving visualization and querying for surveyors, GIS professionals, and the public.
These changes are part of the broader DDS rollout, currently pending beta release (as of February 2026), aimed at making data more accessible, visually rich, and compatible with the modernized NSRS components (e.g., NATRF2022, NAPGD2022, SPCS2022). The DDS landing page will consolidate access, moving away from legacy datasheet formats toward dynamic, web-based delivery.
Accessing Data from NGS. (Presented at GeoWeek 2026)Accessing Data from NGS. (Presented at GeoWeek 2026)Accessing Data from NGS. (Presented at GeoWeek 2026)
During Dan Gillins presentation he highlighted that NGS has three development phases for OPUS underway to support the Modernized NSRS:
OPUS-S 5.2:Multi-GNSS with similar functionality as current OPUS-S
Occupations – one hour or greater
Standard deviations estimate instead of peak-to-peak values
OPUS 6.0:Rewrite of code base in cloud-native application
single/multiple occupations on a single mark
enhanced sharing functionality
Occupation Time – minimum of 4 hours
NGS will review and add these data to the next reference epoch coordinate (REC) adjustment
OPUS 6.1: Extension of OPUS 6.0 for multiple marks in a network
Replace OPUS-Projects functionality
Multiple occupations on a network of marks (campaign-style surveys)
Will allow multiple occupations on a single mark – uploads ~10 data files on a mark
Built for future expansion to support other geodetic measurements (classical, leveling)
I want to emphasize that, in my opinion, NGS is doing a fantastic job with the limited resources that they have. That said, I still have an issue with adopting the new NSRS without having a process for users to submit data to NGS for review, approval, and publication by NGS. This may not be an issue if NGS’s OPUS 6.1 is available soon after the new NSRS is adopted by the Federal Agencies.
My August 2025 GPS World Newsletter discussed the OPUS products under development and, as I mentioned at that time, in my opinion, may be a problem for some users. As I stated in my August newsletter, for the new NSRS to be successfully implemented by users, it is essential that all the necessary software tools are available to enable users to submit projects for review, approval and publication by NGS.
“The NGS News announcement provides a list of products that will be available and a list of products that will not be available when the new NSRS is adopted. Users need to understand what products will not be available after NGS officially adopts the new NSRS so they can determine what that means to their workflow process and client requirements. In my opinion, for the new NSRS to be successfully implemented by users, it is essential that all the necessary software tools are available to enable users to submit projects for review, approval, and publication by NGS. As many of you know, when I worked for NGS, I was the Project Manager of the North American Vertical Datum of 1988 (NAVD 88). That said, from my experience as the NAVD 88 Project Manager, having the appropriate tools available was important for users to implement NAVD 88. As a matter of fact, NGS accepted and processed vertical control data in both NGVD 29 and NAVD 88 for a period to assist users in the implementation of the new vertical reference datum.”
NGS does state that users will be able to submit data through OPUS and OPUS Share to obtain estimates of coordinates in the new NSRS. Unfortunately, using OPUS-Share results that are NOT official NSRS coordinates published by NGS could lead to confusing results and potential lawsuits since NGS does not stand behind the results and recommends NOT using OPUS-Share results for geodetic control.
“This is NGS’s statement on OPUS-Share: Additionally, the popular function of “sharing” your solution with others (colloquially called “OPUS-Share”) will be retained, but with appropriate caveats that the shared solution should not be used as geodetic control. These shared solutions will be available through the geodetic mark pages of the DDS.“
Why should users use OPUS-Share to establish geodetic control when NGS advises against relying on OPUS-Share for establishing geodetic control? OPUS-Share results are not officially submitted to NGS for review, approval, and publication on an NGS Datasheet. I don’t believe this approach will meet the needs of users who require their projects to be reviewed, approved, and published by NGS.
Finally, as someone deeply invested in the geodetic community—having retired from NGS and followed NGS developments closely for years—my overall opinion on the NSRS modernization rollout plan for the remaining products is cautiously positive, but with some genuine concerns that I believe NGS and stakeholders should address head-on to ensure a smoother transition.
The phased beta release approach (starting in 2025 and continuing through 2026) is smart and user focused. Releasing components incrementally on the beta site, allowing at least 6 months of public testing and feedback per major piece (and overall testing extending beyond the final release), shows NGS is prioritizing stability over speed. The emphasis on stakeholder input, FGCS approval (now looking like late 2026 or early 2027), and a multi-month transition to the official site align well with best practices for such a massive shift. It’s encouraging to see private industry partners (e.g., ESRI, Blue Marble) already engaging deeply and planning implementations—success will depend on industry buy-in.
That said, here are my main thoughts and concerns I’d share directly with NGS (perhaps via [email protected], user forums, or upcoming webinars/Q&A sessions):
Timeline uncertainty: Clearer, more frequent milestone updates (beyond the Track Our Progress page) would help manage expectations. For example, monthly or bimonthly “status dashboard” with remaining beta items and projected release windows would be invaluable.
OPUS and processing continuity: The shift away from OPUS-Projects 5 toward OPUS 6 and OPUS-Share is logical for a modern GNSS-centric system, but the lack of a firm end-of-support date for legacy OPUS tools (beyond “at least 6 months’ notice”) creates planning headaches for firms with ongoing projects. NGS should commit to a longer grace period—or ideally a defined parallel support window—for legacy OPUS tools (particularly OPUS-Projects 5) after the official adoption of the modernized NSRS.
Data access and usability in the new DDS: The revamped Geodetic Mark/Station Pages, updated NGS Map interface, and overall Data Delivery System sound promising (more visual, integrated RECs/SECs, photos, etc.), but surveyors rely heavily on reliable, scriptable access (e.g., for bulk queries or automation). If the new web-based system lacks robust APIs or export options comparable to current datasheets/legacy tools, it could hinder efficiency. Beta testers should push hard on this during the 6+ month window.
Transformation tools and legacy data handling: Enhanced web-based tools are key for bridging old-to-new (NAD 83/NAVD 88 to NATRF2022/NAPGD2022), but users need confidence that transformations minimize errors, especially in deformation-prone areas.
Communication and outreach: NGS has improved with webinars, the Presentations Library, and beta feedback channels, and more targeted outreach to state agencies, professional societies (NSPS, AAGS), and software vendors has helped. That said, many in the field still feel “in the dark” about practical impacts—case studies, training resources, and FAQs tailored to common workflows would go far.
In summary, the plan is thoughtful and deliberate, reflecting lessons from past delays. If NGS maintains transparency, incorporates feedback aggressively during beta, and ensures vendor readiness, the modernized NSRS will be a major win for accuracy, sustainability, and GNSS alignment.
I’d encourage anyone reading this (including NGS staff) to test the beta products actively, submit detailed feedback, and participate in forums/Q&As. The community input will make or break the success of this once-in-a-generation update.
The FGCS meeting took place on Wednesday, Jan. 21, 2026. This session was highly informative and played a key role in aligning federal agency engagement strategies and self-assessments in preparation for the final adoption of the modernized NSRS and its associated new datums.
Advancing the use of authoritative geodetic control
Facilitating the modernization of the NSRS across agencies
Recommending the official adoption of the modernized NSRS by the FGDC as the foundational basis for geodetic control throughout the United States.
The agenda for the Jan. 21 meeting is detailed in the section titled “Federal Geodetic Control Subcommittee Meeting.” This gathering supported broader efforts to raise awareness, ensure coordination and prepare agencies for the upcoming transition to the modernized NSRS, with formal approval and release anticipated later in 2027.
Federal Geodetic Control Subcommittee Meeting
January 21, 2026
Agenda:
MC: Christine Gallagher
Time
Topic
Presenter
1:00 – 1:15 pm
Welcome and Introductions
Daniel Roman
1:15 – 1:20 pm
National Geodetic Survey (NGS) Update
Marian Westley
1:20 – 1:30 pm
Geodetic Control Theme Update and its Modernization Timelines
Daniel Roman
1:30 – 2:00 pm
NGS Modernization Engagement Plan and Progress
Dana J Caccamise II / Christine Gallagher
2:00 – 2:15 pm
Bureau of Ocean Energy Management / Kearns & West
Andy Archer / Kyle Vint
2:15 – 2:30 pm
US Census National Spatial Reference System (NSRS) Modernization Preparation
Vince Ossier / Josh Coutts
2:30 – 2:40 pm
Break
2:40 – 2:55 pm
US Department of Transportation NSRS Modernization Preparation
Amy Nelson / Derald Dudley
2:55 – 3:10 pm
American Society for Photogrammetry and Remote Sensing & National Society of Professional Surveyors Working Groups
Chris Parrish / Linda Foster
3:10- 3:50 pm
Discussion: Q&A from Agency presentations. What hurdles to implementation do you see or anticipate? Share your insights from internal working groups
Group Discussion Moderator: Dana J Caccamise II and Daniel Roman
3:50 – 4:00 pm
Closing Remarks
Daniel Roman
Adjourn to Silver Branch
The meeting lasted three hours and covered a lot of material. Below are highlights; contact FGCS for the full meeting recording.
Christine Gallagher, NGS, opened the FGCS session and introduced Dan Roman, NOAA’s National Geodetic Survey senior advisor for geodesy.
Westley’s remarks were brief but important. She noted CO-OPS manages tide gauges and is updating several datums in partnership with NGS, including the Great Lakes International Great Lakes datum. She said the United States and Canada, along with NOS and other federal agencies such as the Corps of Engineers, are heavily involved in Great Lakes management. She also reported that CO-OPS is updating the National Tidal Datum Epoch (current NTDE: 1983-2001) and is working closely with NGS to tie the updated NTDE to the new NSRS. See the image titled “The NTDE Update: New Tidal Datums are Coming!“
During Roman’s comments, he highlighted the agencies and professional societies participating in the meeting presentations and provided an update on the latest rollout schedule for the modernized NSRS.
He emphasized that this Jan. 21, FGCS meeting marks the start of a broader coordination process. The primary purpose of this high-level session was to facilitate the sharing of experiences, strategies, and best practices among federal agencies as they prepare for NGS’s NSRS modernization and the transition to the new reference frames and datums.
Roman noted that future FGCS meetings will shift to a more technical and detailed focus. These subsequent sessions will allow agencies to present their self-assessment results, outline implementation strategies, and discuss progress toward adopting the modernized NSRS.
Key objectives across these meetings include:
Collecting questions and feedback from participants,
Understanding user needs and required accuracy levels,
Identifying anticipated challenges during the transition,
Exploring opportunities for federal agencies to collaborate and support one another throughout the implementation process.
This series of FGCS engagements aims to ensure coordinated, informed, and effective preparation across the federal government ahead of the final adoption and full rollout of the modernized NSRS.
Here are a few key points based on Dan’s remarks:
Today’s presentations provide a broad overview of geospatial data modernization to inform departments about actions they may need to take and to start a dialogue about what each department is doing.
NGS encourages agencies to form working groups; those groups must define their own requirements and create migration plans, including assessing existing data, required accuracies, and the tools needed based on product accuracy statements. [Note: My October 2025 GPS World newsletter highlighted organizations that are forming 2022 Reference Working Groups.] NGS will designate points of contact to facilitate discussions and planning.
FGCS provides guidance on using geodetic data with various tools, models, and SOPs. User needs vary by accuracy: e.g., a 3-meter horizontal allowance (aids to navigation) is straightforward, while 3-centimeter requirements (e.g., FEMA Elevation Certificate) need more precise methods.
Several beta products released in July 2025 are being finalized, enabling the private sector to integrate them into services. NGS is currently developing models and software to transform coordinates from the old datum to the new one. These models are expected around March, and in June/July NGS anticipates releasing an updated Beta NCAT tool to transform coordinates to the new datum. This tool will help users understand differences in local datums.
Final steps include FGCS recommendations for FGDC to adopt the new NSRS and to publish a Federal Register notice on the adoption of the modernized NSRS, anticipated to be completed in early 2027.
After Dan Roman’s comments, Dana J Caccamise II gave a presentation describing NGS Modernization Engagement Plan and Progress. Dana should get an award for material he has prepared and for his work to assist agencies and professional organizations in preparing for the new NSRS. In my October 2025 GPS World Survey Scenenewsletter, I highlighted the work of Dana J. Caccamise II, NGS regional geodetic advisor. Dana has developed vital guidance materials shared with federal agencies — such as the Federal Geographic Data Committee (FGDC) and professional organizations including the National Society of Surveyors (NSPS), American Society of Photogrammetry and Remote Sensing (ASPRS), and American Association for Geodetic Surveying (AAGS).
Here are a few key points based on Dana’s presentation titled “Visualizing Impact: Preparing for NSRS Modernization Through Geospatial Readiness and Collaboration.”
Caccamise said that what started as a focused task quickly grew into a broader strategic effort. He shared insights to encourage thinking about NSRS modernization not merely as a technical update but as a strategic business decision that will shape how agencies create, manage, and share basic data across programs, systems, and partnerships.
Caccamise briefly provided details to the U.S. Census. Before diving into modernization, he offered a personal glimpse of what it’s like to do a federal detail across agencies, noting he was fortunate to do a detail with the Census not long ago.
Image: FGCS Jan. 21, 2026, Public Meeting
Drawing on his experience, Caccamise emphasized the importance of cross-agency readiness and of building resilient trust and communication structures. While on detail at the Census, he was regularly surprised by new challenges, which made the work engaging; he strongly recommended that others take a detail at another agency if they have the opportunity. A key takeaway was the value of visualizing impact: beyond cataloging geospatial datasets, users must identify which support critical decisions, which are shared across agencies, and which risk becoming outdated if you don’t adapt. Mapping themes and workflows revealed real dependencies and, more importantly, vulnerabilities. That detail shifted his focus from “what data do we have” to “what roles does this data play.”
Image: FGCS Jan. 21, 2026, Public Meeting
Efforts around NSRS modernization include a key product developed by Caccamise: the Ready Package. Designed to help agencies assess their readiness for NSRS modernization, the package includes communication tools, technical checklists, and talking points to support agency staff.
Image: FGCS Jan. 21, 2026, Public Meeting
He mentioned that from field-level GIS technicians to senior policy leads, everyone needs to understand what’s changing and why it matters. A key part of engagement is meeting people where they are. Dana has worked with agency partners to raise awareness, build interest, and strengthen understanding — not just of technical changes but of the organizational shifts needed for a smooth transition.
For agencies whose statistical workflows depend on spatially referenced data, that means ensuring location-based datasets remain accurate, comparable over time, and interoperable across programs when the reference system changes. Ultimately, this is about more than new coordinates: it’s about linking strategic planning to operational implementation, from data collection and integration to interagency coordination and informed decision-making.
He mentioned that the big question he’s hearing from many organizations is: how should customers and partners prepare for modernization? He provided the following advice. Start by evaluating your geospatial workflows to understand how the transition will affect data management, operations, and decision-making. Assess dependencies on NGS products and services to ensure continued access and interoperability and proactively identify challenges and opportunities – he mentioned that NGS can’t do this for you because each agency’s situation is unique. Address potential impacts early to reduce operational risk by finding weak points before they cause surprises. Act now: preparing early will minimize future cost and complexity.
Image: FGCS Jan. 21, 2026, Public Meeting
For example, working with the Census under the current national spatial reference system highlights the geographic scope of some operational areas, which span multiple tectonic plates as modeled in the modernized NSRS. Even small regional differences can affect how location-based data are collected, integrated, and compared — especially for programs that need consistent, long-term geospatial baselines. Today, federal agencies commonly use three reference systems — NAD27, NAD83, and WGS84, which complicates geospatial data management.
The Census is a major user and producer of geospatial data, relying on GIS to support operations. This includes the MAF/TIGER geographic database, which contains roads, rail lines, hydrography, landmark features, and legal and statistical boundaries.
Along with many other critical datasets, the Census’s collaborative spatial and statistical research is more effective and interoperable when grounded in a common reference system, such as the National Spatial Reference System.
Image: FGCS Jan. 21, 2026, Public Meeting
Because these datasets are inherently geospatial, many, especially those requiring high positional accuracy or relying on external references such as airborne or satellite data, will be affected by NSRS modernization. The update will enable more consistent data stewardship and support integrated spatial analytics, helping align with individual agency spatial data strategies. Bureau-level geospatial work becomes more effective and future-ready when supported by a modern, shared spatial reference system like the NSRS.
One of the biggest risks is cultural, not technical. If the NSRS is treated as just another dataset, rather than an enabling framework, the foundation for other systems weakens. When the NSRS is recognized as the framework, everything built on it has a solid base. You can’t manage risk if you can’t measure it—and the NSRS is how we measure. Here are a few practical examples.
Floodplain mapping and storm surge models depend on accurate vertical data. Errors of even a foot can leave neighborhoods unprotected or cause unnecessary regulation.
In transportation, subsidence is a hidden risk: roads and bridges may seem fine until precise geometric monitoring reveals sinking.
Shoreline change is a growing challenge; coastal communities need accurate shoreline monitoring for planning and insurance.
In public safety, emergency response relies on precise locations — from 911 calls to field deployments. Seconds and meters matter when lives are on the line.
Image: FGCS Jan. 21, 2026, Public Meeting
As Roman mentioned, Caccamise also stated that the modernized NSRS is being released in phases. Initial beta releases are available now for testing and evaluation—not final production. NGS plans to release the remaining components in beta during this calendar year. The modernized NSRS will replace the current datums at least six months after the final preliminary component is released, giving partners time to review the beta and provide feedback. Near the end of this period, FGCS will convene to discuss and socialize the modernization details and the planned datum replacement.
Next steps for your agency’s modernization:
Evaluate operational needs and identify changes that aren’t necessary.
Assess organizational impacts and staff readiness—are teams prepared for modernization?
Determine how existing programs and regional support will be affected.
Collaborate with partner agencies to align shared datasets, reduce redundancy, and maximize efficiency.
Prioritize leadership and communication to ensure the organization understands the changes.
Plan for future improvements in spatial accuracy, even if you don’t need them immediately.
Image: FGCS Jan. 21, 2026, Public Meeting
As noted by Dan Roman, Dana Caccamise also highlighted that many lower-accuracy datasets may not require coordinate changes beyond updating their metadata—typically those with spatial accuracy on the order of 10 ft or worse. However, he also noted an important caveat: many operational workflows don’t actively read or enforce metadata. In those cases, the risk is not the dataset itself but the accuracy context that becomes embedded as data moves through systems.
An early, critical step is therefore to identify not only which datasets are likely unaffected but also how those datasets are consumed, transformed, and reused. That approach prevents unnecessary work and avoids unintended downstream impacts. Remember: NSRS modernization is more than a technical update, it’s an opportunity to strengthen your agency’s future geospatial capabilities.
Now, I know this newsletter is long, but I would like to highlight one more presentation that I believe provides a model for other agencies to follow. That is, the presentation of the Department of Interior’s Bureau of Ocean Energy Management (BOEM) activities presented by Kyle Vint (Vice President, Kearns & West) – “From Proactive Engagement to Lasting Impact: BOEM’s Path to Datum Readiness.”
Image: FGCS Jan. 21, 2026, Public Meeting
Kearns & West is a communications and engagement specialization firm. The materials that they develop to support internal communications and outreach within an organization are available for other organizations. They provided a QR code for others to access their resources.
Vint outlined BOEM’s operating context and described how the agency is proactively addressing NSRS modernization, including several strategies.
Image: FGCS Jan. 21, 2026, Meeting
BOEM’s challenges are partly historical: until about 2010, it was part of a parent agency that has since split into three separate agencies. That fragmentation means BOEM must coordinate data and change management not only internally but across three agencies that share data centers and geospatial datasets. BOEM relies on authoritative geospatial data to manage offshore energy and mineral activities on the Outer Continental Shelf; BOEM’s Geospatial Services Division supports this by maintaining leases and boundaries that underpin program decision-making. Because the ocean serves many purposes, BOEM relies on multiple layers of information from different agencies to support those decisions.
BOEM’s path to modernization is further complicated by internal organizational factors. The agency struggled with the NAD27-to-NAD83 transition due to resource constraints and misunderstandings — some staff believed modernization would alter legal lease blocks, which they expected to be immutable — so the transition was not fully implemented.
Image: FGCS January 21, 2026, Meeting
BOEM holds large datasets in both NAD27 and NAD83, fragmenting its workflow. Maintaining and converting between multiple reference systems is labor-intensive and introduces inconsistencies.
BOEM must dedicate substantial staff time to managing data in multiple reference systems. BOEM’s Geospatial Services Division recognized early that continuing workarounds would increase risk over time, so they began proactive modernization planning.
The Geospatial Services Division saw this as more than a technical issue — it’s also a people, communication, and resourcing challenge. BOEM shifted from fragmented efforts to a proactive, multi‑year planning approach emphasizing governance, leadership buy‑in, and clear communication. The Geospatial Services Division established a milestone‑based approach for consistent messaging and coordination across stakeholders and offers internal expertise to support programs and regions as they assess costs and technical complexity.
Their strategy seeks common ground to pool resources for shared problems and to use the Geospatial Services Division as an internal augmentation so individual offices aren’t forced to opt out. This reduces cost uncertainty and enables realistic planning for timelines and required participants.
Image: FGCS January 21, 2026, Public Meeting
As part of the process, user personas were created to identify who would struggle with each step and who would benefit from early, sustained engagement. For each group, they defined the value of participating and explained why they were invited.
BOEM leaderships were treated like investors—they ensured they brought geospatial experts to meetings so questions could be answered, and so leadership had actionable budget information for long‑term planning. At the program and regional level, data experts who know existing datasets, reference systems, dependent applications, and potential workflow challenges were part of the process.
They also documented internal roles so others can model the approach. The Geospatial Services Division coordinates the effort across the organization. Program and regional experts provide domain knowledge. Kearns & West (technical and communications contractors) supported messaging, prepared materials, and ran meetings so BOEM staff could focus on the conversation. Clear roles and sustained engagement have been critical in this multi‑year planning effort.
Image: FGCS January 21, 2026, Public Meeting
The team developed a Survey and sent it to each program and region to gather resource requirements. The survey asked what data they have and its characteristics, which applications or workflows depend on that data and could be affected by modernization, and what technical resources they expect will be needed to support budgeting.
Image: FGCS January 21, 2026, Meeting
As part of the process, they are building internal champions to advocate for the effort, simplifying complex issues so staff can brief leadership, and convening agencies, partners, and industry to co-create solutions.
Happy New Year! I’ve always felt that a fresh calendar represents a world of new opportunities, and I wish you all a fantastic 2026. For many, this is a season for reflection and self-improvement, with goals typically centered on fitness, faith, personal growth or career milestones.
As regular readers of this newsletter know, my primary focus over the past year has been to champion the importance of geodesy and to prepare the geospatial community for the National Geodetic Survey’s modernized National Spatial Reference System (NSRS).
To see how modern tech would handle such a specialized professional niche, I asked the AI chatbot Grok: “What would be a good New Year’s resolution for a user of the National Spatial Reference System?”
The response was quite insightful. Take a look at what it suggested below.
What would be a good New Year’s Resolution for a user of the National Spatial Reference System? (Grok’s Response)
Fun and Practical New Year’s Resolutions for NSRS Users
As we head into 2026, the modernization of the NSRS is in full swing. NOAA’s National Geodetic Survey (NGS) released the first beta products in June 2025, with ongoing rollouts and testing throughout the year. The full transition to new frames like NATRF2022 and NAPGD2022 is expected soon, bringing centimeter-level accuracy aligned with GNSS and global standards—but it requires preparation.
Here are some timely, geodesy-inspired New Year’s resolutions tailored for surveyors, GIS professionals, engineers, and anyone relying on the NSRS:
Fully transition workflows to the modernized NSRS. Commit to updating software, processes, and datasets for the new terrestrial reference frames and geopotential datum. Test tools on the NGS Beta site and provide feedback to help shape the final rollout.
Achieve new heights (and accuracies) in 2026. Embrace NAPGD2022 for more precise orthometric heights. Resolve to reprocess key projects with updated transformations (via NCAT or VDatum) and say goodbye to NAVD 88 quirks.
Stay grounded in best practices. Incorporate the latest NGS guidelines, like NOS NGS 92 standards for GNSS surveys. Attend webinars and workshops, or review resources, to keep your positioning sharp.
Contribute to the system. Submit high-quality GNSS data via OPUS-Share or participate in crowdsourced efforts to improve the network. Help make the NSRS even more robust for everyone.
Measure progress monthly. Track how the modernization impacts your work—review coordinate shifts, audit legacy data, and plan for smoother integrations in future projects.
These resolutions blend practicality with the spirit of improvement that defines geodesy. Happy New Year—may your positions be accurate, your elevations precise, and your datums forever modernized! For the latest updates, check geodesy.noaa.gov.
It’s no surprise that Grok highlighted the NSRS modernization; it even incorporated a photo of a geodetic benchmark I took for my July 2025 GPS World Survey Scenenewsletter.
Understanding that most AI chatbots personalize results using past interactions (unless disabled), I wanted to test this. After clearing my cache and deleting all previous Grok interactions, I posed the question again.
You can find that second, impersonalized response below.
Second Response from Grok
What would be a good New Year’s Resolution for a user of the National Spatial Reference System? Grok’s Second answer.
Here are some practical, realistic, and useful New Year’s resolutions tailored for someone who regularly works with the NSRS whether you’re a surveyor, GIS professional, geodesist, engineer or data manager:
“This year, I will stop mixing epochs without documenting them.” Resolve to always record the reference epoch (e.g., 2010.0, 2020.00) when I use NAD83(2011), NAD83(CORS96), NAD83(2011) epoch-specific coordinates, or when I transform to ITRF2020/2020.0. Bonus: add epoch to layer names and metadata.
“I will run OPUS or CSRS-PPP at least once a month to keep my local control fresh.” Make it a habit to periodically re-observe a trusted point and submit it to NOAA’s OPUS (or CSRS-PPP in Canada) to verify that my local network hasn’t drifted too far from the national datum.
“I will finally transition at least one active project to the modern NSRS (NAD83(2011)/NAVD88 → NATRF2022 / NAPGD2022).” Pick one ongoing or new project and do the full datum shift. Learn the tools (NADCON5, VERTCON3, GEOID18 → GEOID2022) and document what changed.
“I will replace every ‘NAD83’ label that doesn’t specify an epoch or realization with something more precise.” No more generic “NAD83” in reports, plats, or metadata. Aim for “NAD83(2011) epoch 2010.0” or “NAD83(2011) CORS-derived” — or better yet, start using NATRF2022 when appropriate.
“I will learn to use the NGS Coordinate Conversion and Transformation Tool (NCAT) fluently.” Commit to doing at least 5 conversions or transformations per month in NCAT instead of relying on old software or hand-calculated factors.
“I will check the NGS Data Explorer / Datasheet for every benchmark or CORS I plan to use — before I use it.” No more assuming a published value is still good. Make it a 2-minute ritual to look up the latest adjusted position and velocity.
“I will attend at least one NGS webinar or read one Bluebook chapter in 2026.” The NGS webinar series is free and excellent. Pick one session (e.g., on GEOID2022, NATRF2022 implementation, or GNSS vector processing) and actually watch it.
“I will prepare a small ‘before/after’ datum comparison report for my organization or clients.” Quantify what the 2022–2025 NSRS modernization means in your typical project area (horizontal shift, orthometric height change). Even a one-page summary builds understanding and credibility.
“I will stop treating GEOID18 as the final word and start using GEOID2022 for new work.” Especially important for projects that will live past 2025, as NGS is phasing out support for older geoids.
Pick one or two that feel achievable and most relevant to your day-to-day work. My personal favorite starter resolution for most NSRS users in 2026: “In 2026, I will clearly label the datum, realization, epoch, and geoid model on every deliverable I produce.”
That one habit alone dramatically reduces confusion downstream.
I really appreciate Grok’s responses because they address crucial issues that many geospatial users either overlook or take for granted, emphasizing the importance of proper documentation and associated metadata.
Key Resolution Examples:
Specificity: “I will replace every ‘NAD83’ label that doesn’t specify an epoch or realization with something more precise.”
Verification: “I will check the NGS Data Explorer / Datasheet for every benchmark or CORS I plan to use — before I use it.”
It is important to note that the AI chatbot assumes the modernized NSRS has already been adopted, which, as of January 2026, is not the case. This highlights that AI still has limitations and requires human oversight.
I challenge you to ask your own AI chatbot a similar, niche question related to your profession and compare its responses.
Beyond the specific technical corrections, Grok provided excellent general advice for any geospatial professional. Take, for example, action items 1 and 5 from its first response:
Transition Workflows: Commit to fully updating software, processes, and datasets to align with the new terrestrial reference frames and geopotential datum.
Measure Progress Monthly: Track the real-world impact of modernization by reviewing coordinate shifts, auditing legacy data, and planning for smoother integrations in upcoming projects.
Even though the modernized NSRS has not yet been officially adopted as of January 2026—with official release and FGCS approval expected later this year—following these steps now ensures you are prepared for the official transition when it occurs.
To help your team prepare for the official transition later this year, I’ve included a box titled “Questions to Guide a Self-Assessment of Your Operation and Products.” These questions, originally featured in my October newsletter, are designed to ensure your organization is fully equipped to implement the new NSRS the moment it is adopted.
Are you generating or using geospatial data (or doing both)?
If so, your workflows are likely dependent on geodetic control tied to one or more NGS products. The upcoming NSRS update will affect these dependencies. (See the box titled “List of NGS Products and Services.”)
Do you know if your mission, project, or datasets depend on NGS products?
Identifying whether and how your entity relies on NGS products is a critical first step in assessing potential impacts.
What are your accuracy, precision, and shelf-life requirements for geospatial data?
Understanding your mission’s specific data requirements ensures you can evaluate whether NSRS modernization will meet your operational needs without unnecessary adjustments. This should include plans to accommodate greater accuracy in the future.
Do you know how your entity accesses and utilizes geospatial data?
Are you obtaining it directly from NGS or indirectly through third-party vendors (e.g., RTN systems, GIS platforms, GNSS companies)?
Many entities rely on geodetic control without realizing it. NGS’s foundational data and frameworks are often invisible and seamlessly embedded within the tools and services offered by third-party vendors, such as GIS platforms, survey equipment, and software providers. These vendors, in turn, depend heavily on NGS products like the NSRS to ensure their tools are accurate and functional. Understanding this indirect reliance is crucial for preparing your workflows and ensuring continuity as the NSRS is modernized.
Where does your entity fit in with the geodetic workflow?
Does your entity create integral products (e.g., GNSS data, Lidar data) on which other products depend?
Evaluating these dependencies will help you determine the scope of NSRS modernization impacts.
What are your project requirements for data accuracy and longevity?
Assess whether your data accuracy thresholds and long-term usability align with the modernized NSRS.
Have you evaluated workflows and identified potential impacts in areas affected by significant ground movement (e.g., regions with tectonic shifts, vertical land motion, and, most notably, subsidence)
Identifying potential risk or disruption areas can guide prioritization and help mitigate impacts on critical operations.
While the original meeting scheduled for October 15, 2025, was canceled due to the Federal Government Shutdown, it has been officially rescheduled for Wednesday, January 21, 2026. This meeting will be critical for aligning agency engagement strategies and self-assessments ahead of the final adoption of the new datums.
Increase awareness of the National Spatial Reference System (NSRS) Modernization rollout schedule and engagement strategy, including self-assessment and interaction between official departmental working groups and an NGS point of contact.
Within other Departments, connect decision-makers to those who accomplish NSRS modernization tasks and designate points of contact to interface with NGS capacity-building efforts.
Share experiences and strategies among federal agencies concerning NSRS Modernization self-assessment and preparation.
(New) Formally transition the foundational beta products (released in May 2025) from preliminary to final.
Gather questions, discuss anticipated challenges, and identify opportunities to support each other through this transition.
The FGCS plays a central role in coordinating geodetic activities across the federal government, including the development of standards and the promotion of the use of authoritative geodetic control (e.g., CORS, geoids) to ensure that geospatial data is accurate, accessible, and interoperable, and to advance the modernization of NSRS across agencies and recommend the adoption of the modernized NSRS by FGDC as the official basis for geodetic control in the United States. It is my understanding that this meeting is open to the public (virtually) for listening and observation. The box titled “Federal Geodetic Control Subcommittee Meeting” provides the agenda of the January 21, 2026, meeting.
Federal Geodetic Control Subcommittee Meeting Agenda held January 21, 2026.
To join the meeting virtually, registration is required. You can find all the necessary details and a direct link to sign up in the box titled “Registration for the Virtual Attendance of the Meeting.”
NOAA’s National Geodetic Survey (NGS) invites you to the upcoming Federal Geographic Data Committee (FGDC) Federal Geodetic Control Subcommittee (FGCS) meeting.
In October 2025, NSPS held its Fall meeting. The box titled “Excerpts from 2025 NSPS Fall Meeting Report: October 17, 2025” contains excerpts from the report provided by Richard Kleinmann, Wisconsin NSPS Director, on the working group’s activities being performed by the National Society of Professional Surveyors (NSPS) Professional Standards NSRS Modernization Subcommittee.
Submitted by: Richard Kleinmann PLS, Wisconsin NSPS Director
Subcommittee Purpose: To promote awareness, adoption, and readiness for the implementation of the Modernized National Spatial Reference System (NSRS) in cooperation with the National Geodetic Survey (NGS) and other geospatial groups.
Activities: NSPS leadership and the NSRS Modernization Subcommittee continue to work closely with NGS to promote awareness, adoption, and readiness for the new 2022 datums, which are expected to be approved sometime in 2026. Due to federal funding challenges occurring in 2025, NSPS felt it necessary to intensify its support of NGS and the modernization of the NSRS which was the genesis of this subcommittee.
The NSRS Modernization Subcommittee is also working on a series of documents originally developed by Dana J. Caccamise of NGS intended to be used by Federal Agencies in the transition to the new datums. We are adapting the documents to change the “voice” from NGS to NSPS and the intended audience to state, regional, county and local agencies, as well as private practitioners, to help them transition smoothly to the modernized NSRS. At this point, the document package includes:
Briefing materials for agency coordination (Presentation Template)
These document resources are being developed with the hope to share them via NSPS social media outreach efforts and possibly a geospatial information “hub” shared by NSPS and other geospatial organizations.
Proposed Whitepapers/Use Case Reports: The intent of these whitepapers is to is to provide a somewhat higher-level view of how the transition to the new datums/frames can be accomplished by showing what tools are available and what to consider when designing a project approach. Our hope is to promote the adoption of the new datums and share the benefits of doing so. Basically, adopting a “be prepared, not scared” attitude. We are looking for people willing to share their solutions so others can benefit from their experience and be more likely to be early adopters. It is not our intent to develop detailed step by step recipes that can be blindly followed because every geographic region has their unique circumstances that need to be considered but the white papers will instead supply the foundation for them to confidently build a project approach that works in their situation.
Coordination with other working groups: NSPS is looking forward to coordinating with similar Working Groups that NGS has encouraged to be formed by the American Society for Photogrammetry and Remote Sensing (ASPRS) and the American Association for Geodetic Surveying (AAGS). There are several Task Forces and Committees formed on the state level that are also working on adoption and implementation issues specific to their states. Together, these efforts aim to build understanding, reduce uncertainty, and support the geospatial community’s successful implementation of the updated reference framework. NSPS and NGS have committed to having a significant presence at Geo Week in Denver, Colorado, on February 16-18, 2026.
As mentioned in the working group’s report, “As an outgrowth of interaction between NSPS & NGS during NGS quarterly meetings and at geospatial events such as the ESRI User Conference and Geo Week, the NSPS leadership team and subsequently the NSRS Modernization Subcommittee began developing a suite of resources — including an ArcGIS StoryMap with several resources useful for the transition. See the link for the NSPS ArcGIS Story map here: https://share.google/oOAIapPQnux5q8nwl.
The box titled “NSPS ArcGIS Story Map” offers a detailed look at this resource, which visually illustrates the impact and benefits of the upcoming NSRS modernization.
NSPS ArcGIS Story Map
The website has five buttons:
Overview
What to Expect
How to Prepare
Resources
Note to Users
The section titled “The Overview Section” details the essential information — who, what, where, when, and why — regarding the new, modernized NSRS. Additional information is available on the website.
Overview
WHO: The National Geodetic Survey (NGS), located within the National Oceanic and Atmospheric Administration (NOAA) of the United States government. The NGS is responsible for defining, maintaining, and providing access to the country’s positioning infrastructure called the National Spatial Reference System (NSRS).
WHAT: Is updating the NSRS – horizontal (geometric, NAD 83) and vertical (geopotential, NAVD 88 and local island vertical datums PRVD02, USVI09, ASVD02, GUVD04, HAWAII – Local Tidal) geodetic datums, an effort that has been underway since 2007.
WHERE:The North American, Pacific, Caribbean, and Marianas plates.
WHEN: Now – rollout is underway. An updated Federal Register Noticewas released on October 9, 2024. Alphaand Betaproducts are being released, with full replacement of the NSRS anticipated in 2026.
WHY: These datums have been in use since GPS was in its infancy – i.e., for decades, and there are known limitations that the new system addresses:
NAD 83 is not as geocentrically defined as today’s positioning technologies demand, meaning not referenced to the center of Earth’s mass, by about 2.24 meters based on the latest international estimates. This is problematic when using Global Navigation Satellite Systems (GNSS), which orbit about and provide positions relative to the center of the Earth.
NAD 83 grouped the North American and Caribbean plates in its definition. The updated system has broken those two plates out (because we now understand how to measure how the plates rotate individually) in addition to the Pacific and Marianas plates included in NAD 83, resulting in definitions for four Terrestrial Reference Frames (TRFs): NATRF2022, PATRF2022, MATRF2022, and CATRF2022.
Continental drift and vertical land movement were not accounted for in the existing NSRS. Reference epochs (timestamps, for instance) for coordinates have been introduced for survey data to help us better understand movement or change over time.
Based on current international geoid estimates, NAVD 88 is biased by approximately 1.5 meters and tilted by 1 meter coast-to-coast.
There are currently multiple vertical datums. The new system will consist of one.
NAD 83 and NAVD 88 were designed independently, resulting in reduced accuracy. In the new system, they were designed together, resulting in better integration and higher accuracy.
GEOID 18 and previous models were hybrid models “warped” to match leveled benchmarks. GEOID2022 will be a more consistent and stable model as it is a purely gravimetric geoid model.
Currently, both physical marks and continuously operating GNSS stations are relied upon for the existing NSRS. Physical marks degrade and are destroyed over time, negatively affecting height and position data. The modernized NSRS will rely exclusively on GNSS stations.
State Plane Coordinate System 83 (SPCS 83) includes high levels of distortion for many areas. The modernized SPCS2022 minimizes distortion or scale error (the difference between ground and grid measurements) at the topographic surface rather than the reference ellipsoid surface, and is designed to minimize distortion in populated or high-use areas.
An important change between SPCS 83 and the upcoming SPCS2022 is that only the international foot (1 foot = 0.3048 meter, exactly) will be supported, which differs from SPCS 83, with some states officially using the international foot while others use the U.S. survey foot (1 foot = 1200/3937 meters). This is consistent with the deprecation of the U.S. survey footinitiated by the National Institute of Standards and Technology (NIST) at the end of December 2022.
The website makes it easy to spread the word about NSRS modernization. By clicking the share button on the right side of the page, you can access several ways to distribute the story map with colleagues or on social media.
The Sharing the NSPS ArcGIS Story Map includes more details — it even includes an embedded QR code that you can scan to open the map directly on your mobile device.
You can access it on your mobile device using the code below.
NSPS ArcGIS Story Map QR Code
For those who prefer a physical copy or a clean PDF, the site also offers a print-friendly version. See the box titled “NSPS ArcGIS Story Map – Print View” for instructions on how to access it. This 15-page document provides all the same information as the interactive site in a consolidated, easy-to-read format.
NSPS ArcGIS Story Map – Print View
As highlighted in the NSPS working group’s October report, both NSPS and NGS are committed to a major presence at Geo Week in Denver, Colorado, from February 16–18, 2026.
A key session, “NSRS Modernization – The Latest Technical Updates,” is currently scheduled for February 17, 2026, at 2:00 PM. For more details on the presentation and speakers, refer to NSRS Modernization – The Latest Technical Updates below.
2:00 PM – 3:30 PM MT
Bluebird Ballroom 1A
The National Spatial Reference System (NSRS) is undergoing a major transformation to provide more accurate, accessible, and consistent geospatial reference data across the United States. This session will present the latest technical updates on NSRS modernization, including advancements in geodetic reference frames, updated survey standards, and enhanced tools for positioning and measurement. Attendees will learn how these changes impact surveying, mapping, infrastructure, and engineering projects, and gain practical guidance for integrating modernized NSRS data into workflows. This session is essential for professionals seeking to stay current with the evolving national geospatial reference framework.https://mail.google.com/mail/u/0/#search/lfoster%40esri.com/FMfcgzQcqtcPbfppZtnTpZZWDMkQcXfk?projector=1&messagePartId=0.1
I wish you all a prosperous 2026 filled with wonderful new relationships, exciting opportunities, and continued happiness and success.
In my August 2025 GPS World newsletter column, I highlighted that a colleague reminded me that the National Geodetic Survey’s (NGS) new National Spatial Reference System (NSRS) is more than a technical upgrade. It offers a prime opportunity to review and improve current processes and workflows, examine existing products and considerations, and plan strategically for future needs. By auditing geospatial data dependencies now, NSRS users can assess how transitioning to the new datum will affect workflows, datasets and operational decision-making.
Several organizations have formed working groups to address the new NSRS. The National Society of Surveyors (NSPS) has released a story map to inform the professional surveying community and is developing guidance and case studies. The American Association for Geodetic Surveyor (AAGS) is collaborating with NSPS. The American Society of Photogrammetry and Remote Sensing (ASPRS) has prepared materials available on its website. Additionally, under the leadership of Gary Thompson, the North Carolina Geodetic Survey established the North Carolina 2022 Reference Frame Working Group. The group’s goal is to address issues related to the implementation of the datum change in 2026. It includes representatives from North Carolina agencies involved in producing or using geospatial products and services.
Agencies Involved in the NC 2022 Reference Frame Working Group
NC Geodetic Survey
NC DOT Hydraulics
NC State Mapping Advisory Committee
NC Geographic Information Coordinating Council (GICC)
NC State, Land Records Management
NC Geodetic Survey Advisory Committee
NC Center for Geographic Information & Analysis
NC GICC Local Government Committee
NC Society of Surveyors
NC DOT State Location & Surveys
NC State Mapping Advisory Committee
Duke Energy
NC DOT Photogrammetry Unit
NC GICC Local Government Committee
U.S. National Geodetic Survey
The organizations participating in the NC RFWG are assessing how changes in the new NSRS may impact their geospatial workflows and evaluating their reliance on NGS products and services. Proactive self-assessment is essential because NGS cannot customize support for each entity’s unique needs and processes. By identifying potential challenges and opportunities early, organizations can adapt smoothly and maintain operational efficiency during the transition. The following were the key action items from the last NC RFWG meeting:
Create an information sheet to help local governments prepare for the data change
encourage agencies to consult their software vendors on support measures for the new datums
establish a rule for when to use the U.S. Survey Foot versus the International Foot
review current data files to ensure their metadata includes datum and unit information.
Many participants of the North Carolina working group expressed interest in understanding how much the coordinates will shift with the new NSRS. While NGS’s website offers diagrams that provide a high-level overview of coordinate and product changes, many users sought more detailed information specific to North Carolina. To address this, I used NGS’s Multi-Year CORS Solution 3 (MYCS3) update of the NOAA CORS Network to ITRF2020, epoch 2020.0, to estimate the changes between the current NSRS — NAD 83 2011 (epoch 2010.0) — and the upcoming NSRS in North Carolina, such as NATRF2022 at epoch 2020.0. This approach offers a more detailed view of the magnitude of shifts in local regions. The figure titled “Approximate Differences Between NATRF2022 (Epoch 2020.0) and NAD 83 2011 (Epoch 2010.0) in NC” illustrates the approximate horizontal coordinate differences between the current NSRS and the future NSRS based on NCN CORS data. (Note that these units are in feet.) For additional information on MYCS3 and regional changes across the United States, refer to my August 2025 GPS World column.
Approximate differences between NATRF2022 (Epoch 2020.0) and NAD 83 2011 (Epoch 2010.0) in North Carolina. Horizontal change in feet. (Credit: Dave Zilkoski)
Differences in orthometric heights between the new NAPGD2022 and the current NAVD 88 are significant for anyone working with FEMA flood maps or preparing flood insurance elevation certificates. I used ITRF2020, epoch 2020.0, ellipsoid heights from NOAA CORS stations along with Geoid2022 values to estimate the NAPGD2022 orthometric heights at the CORS sites. As depicted in the plot, the height differences between NAPGD2022 and NAVD 88 across North Carolina range from about 0.5 feet in the southeastern region to over a foot in the northern and western regions. (Note that the units are in feet.)
Approximate differences between NAPGD2022 and NAVD 88 in North Carolina. Orthometric height change in feet. (Credit: Dave Zilkoski)
This type of information should be shared with managers of real-time GNSS networks(RTN). RTN operators could then establish a parallel beta system to enable users to understand how the new NSRS may affect their products and services. (Note: The North Carolina Geodetic Survey, which manages the NC CORS/RTN system, is considering running a pilot parallel RTN based on the new NSRS.) This data can be valuable for RTN users to assess how coordinate changes might influence their workflows. For example, it can help determine how the shifts in coordinates will affect agricultural activities such as planting, fertilizing and harvesting. Will farmers need to remap their fields, or will a transformation be sufficient?
Fostering collaboration with stakeholders and constituents will help users better understand how the NSRS modernization impacts their products and services. Developing strategies to align geospatial data management with regulatory requirements and operational objectives will also facilitate a smoother implementation process. NGS is partnering with federal agencies and professional societies to create a self-assessment guide that helps organizations evaluate how the NSRS update affects their geospatial missions. As previously mentioned, the North Carolina 2022 Reference Frame Working Group is working with state and local agencies, as well as surveyors, to proactively address key questions and challenges. This collaboration aims to improve communication with NGS and determine whether their products and services need to be reprocessed, re-surveyed or transformed to suit the new standards.
Each organization has its own unique geospatial requirements and a thorough understanding of its mission and needs. This is an ideal opportunity to develop a centralized plan for evaluating and managing geospatial workflows during the transition to the modernized NSRS. Challenges include aligning legacy datasets with new reference standards while ensuring data integrity. Organizations should assess the accuracy of their data in relation to the NSRS and document any necessary updates in metadata. By creating a well-structured plan that balances operational constraints, legal compliance and practical considerations, organizations can prioritize accuracy, efficiency and alignment with the updated NSRS.
To assist others in preparing for the new NSRS, Dana J. Caccamise II, NGS regional geodetic advisor, has developed guidance materials that have been shared with federal agencies — including the FGDC and their team leaders — and professional organizations such as NSPS, ASPRS and AAGS. See the boxes titled “Questions to Guide a Self-Assessment of Your Operation and Products” and “List of NGS Products and Services — Are your workflows dependent on one or more NGS products.” The goal is to help these agencies become ready to implement the new NSRS once it is officially adopted by NGS.
Questions to Guide a Self-Assessment of Your Operation and Products
Are you generating or using geospatial data (or doing both)? – If so, your workflows are likely dependent on geodetic control tied to one or more NGS products. The upcoming NSRS update will affect these dependencies. (See “List of NGS Products and Services.”)
Do you know if your mission, project, or datasets depend on NGS products? – Identifying whether and how your entity relies on NGS products is a critical first step in assessing potential impacts.
What are your accuracy, precision, and shelf-life requirements for geospatial data? – Understanding your mission’s specific data requirements ensures you can evaluate whether NSRS modernization will meet your operational needs without unnecessary adjustments. This should include plans to accommodate greater accuracy in the future.
Do you know how your entity accesses and utilizes geospatial data? – Are you obtaining it directly from NGS or indirectly through third-party vendors (e.g., RTN systems, GIS platforms, GNSS companies)? – Have you considered how updates to NGS products may impact the tools or services you rely on from these vendors? – Many entities rely on geodetic control without realizing it. NGS’s foundational data and frameworks are often invisible and seamlessly embedded within the tools and services offered by third-party vendors, such as GIS platforms, survey equipment, and software providers. These vendors, in turn, depend heavily on NGS products like the NSRS to ensure their tools are accurate and functional. Understanding this indirect reliance is crucial for preparing your workflows and ensuring continuity as the NSRS is modernized.
Where does your entity fit in with the geodetic workflow? – Does your entity create integral products (e.g., GNSS data, lidar data) on which other products depend? – Does it produce derivative products (e.g., DTM, Topographic Map, Flood Insurance Rate Map (FIRM) and Flood Insurance Study (FIS) Report)? – Evaluating these dependencies will help you determine the scope of NSRS modernization impacts.
What are your project requirements for data accuracy and longevity? – Assess whether your data accuracy thresholds and long-term usability align with the modernized NSRS.
Have you evaluated workflows and identified potential impacts in areas affected by significant ground movement (e.g., regions with tectonic shifts, vertical land motion, and, most notably, subsidence) – Identifying potential risk or disruption areas can guide prioritization and help mitigate impacts on critical operations.
List of NGS Products and Services
Are your workflows dependent on one or more NGS products
Products and Services
Examples
Geodetic Control Data
– Datasheets – State Plane CoordinatesSurvey – MarksSurvey Data
NGS Geodetic Tool Kit – NGS PC Software such as ADJUST – User-Contributed Software – VDatum to convert elevation data – Other NSRS Resources such as transformation tools
GNSS Data and Solutions
OPUS (Online Positioning User Service) – CORS (Continuously Operating Reference Stations) – Satellite Orbits
Gravity Data
– Gravity for the Redefinition of the American Vertical Datum (GRAV-D) – Deflection of the Vertical (DoV)
Coastal Mapping Products
– Topobathy lidar Data – Shoreline Mapping Products
Aerial Imagery and Remote Sensing
– NOAA Remote Sensing Division Products such as Emergency response imagery (e.g., hurricane damage)
Analytical tools
– Least squares analysis tool – Antenna Calibrations
GIS and Visualization Tools
– Geospatial Data such as Shapefiles and KML files for GIS applications – Web Services
Educational and Reference Materials
– Documentation such as NGS technical reports – Presentations and Posters – User support such as NGS Information Center and Regional Geodetic advisors
Historical Data Archives
– Legacy Products such as Older geodetic survey records and Superseded geoid models and transformation tools
Standards and Procedures, best practices, data formats
– Standards and Procedures such as NOAA Technical Memorandum NOS NGS 92 – Data Formats such as GVX (Real-time or post-processed GNSS vectors)
To support the increased awareness of the modernization of the NSRS, under the auspices of the Federal Geodetic Control Subcommittee, NGS will host a meeting with federal geospatial agencies on Oct. 15, 2025, to discuss the NSRS modernization. The primary objectives of this meeting are to:
Increase awareness of the NSRS modernization rollout schedule and engagement strategy, including self-assessment and interaction between official departmental working groups.
Within other departments, connect decision-makers to those who accomplish NSRS modernization tasks and designate points of contact to interface with NGS capacity building efforts.
Share experiences and strategies among federal agencies concerning NSRS modernization self-assessment and preparation.
Gather questions, discuss anticipated challenges and identify opportunities to support each other through this transition.
It is my understanding that this meeting is open to the public (virtually) for listening and observation. See below for more information on the meeting.
I recommend that NSRS users consult guidance from NGS and engage with professional societies that have established working groups to analyze the impact of the new NSRS on geospatial products and services. Getting involved now will help ensure you are prepared when NGS officially adopts the updated NSRS. As Dru Smith, NGS NSRS modernization manager, explained in his webinar titled “NSRS Modernization — Big Steps Forward and What Comes Next” on Aug. 14, 2025, once the initial set of products and services of the modernized NSRS is “official,” the new NSRS becomes “The NSRS,” and its implementation then begins.
Are you prepared to implement the new NSRS once NGS officially adopts it? Do you have the necessary tools and resources in place to support a smooth transition? This newsletter highlighted several actions that users can take now to ensure they are ready to implement the new NSRS when it becomes official.
The California Spatial Reference Center (CSRC) modernized the California Spatial Reference Network (CSRN) on July 31, 2025. The new California Spatial Reference Network is denoted as CSRN Epoch 2025.00.
These coordinates changes affect California geospatial users, but the transition process to the new epoch is something that others should understand to prepare for the new, modernized National Spatial Reference System (NSRS), which is expected to be adopted in 2026. As I mentioned in my August 2025 newsletter, NSRS users should proactively assess their geospatial data dependencies and evaluate how adoption of the new datum will affect workflows, datasets and operational decision‑making.
The California Spatial Reference System (CSRS) is the official geodetic datum in California, as published by the California Spatial Reference Center (CSRC) according to Public Resources Code (PRC) §§8850–8861. The image below depicts the CSRN. It is rigorously aligned to the current definition of the National Spatial Reference System (NSRS) through a set of coordinate transformations from ITRF2020 to NAD83(2011) as published by the NOAA/NOS National Geodetic Survey (NGS). The California Spatial Reference System (CSRS) is realized by the geodetic coordinates and uncertainties of the CSRN on the date of 2025.00 (January 1, 2025; GPS week 2347, day 3) of 1068 GNSS stations (881 active and 187 defunct stations) in California and at the borders of Arizona, Nevada, Oregon and Baja California. CSRN Epoch 2025.00 NAD83(2011) replaces the previous CSRS Epoch 2017.50 NAD83(2011).
The latest hybrid geoid model GEOID18 published by NGS was used to compute Global Navigation Satellite System (GNSS)-derived orthometric heights (DCOH) on the North American Vertical Datum of 1988 (NAVD 88) datum in accordance with the California PRC §§8890-8902 (California Orthometric Heights).
Plot of CSRN (Credit: SOPAC)
As previously mentioned, the new CSRC Epoch 2025.00 (NAD83 (2011) replaces the previously published CSRC Epoch 2017.5 NAD83 (2011). Readers can obtain the project report that provides technical information about the new realization at the following link: https://sopac-csrc.ucsd.edu/index.php/csrn-epoch-2025-00/ . The website provides web-links to the project report and a table of stations that includes information about the coordinates. See the image captioned “Excerpt from CSRC Epoch 2025.00 Web Page” for the links to the reports and tables. The CSRC Epoch 2025.00 realization is aligned with NAD83 2011, Epoch 2010.0. See the image captioned “Excerpt from Project Report V2” for the summary from the report. I have highlighted some sections of the summary that I thought others would find of interest.
This report, prepared under California Department of Transportation (Caltrans) Contract No. 52A0157, Task Order 1, documents the modernization of the California Spatial Reference Network (CSRN) by the California Spatial Reference Center (CSRC). This updated realization aligns the CSRN with the North American Datum of 1983 (NAD83 2011, epoch 2010.00).
The new reference frame, effective on January 1, 2025 (GPS Week 2347, Day 3), is called CSRN Epoch 2025.00 NAD83(2011), referred to for short as CSRN Epoch 2025.00. It replaces the previous adjustment at Epoch 2017.50 and remains a core component of the California Spatial Reference System (CSRS).
The CSRN is defined by the geodetic coordinates and uncertainties (Table 1) of 1,068 continuous GNSS stations—881 active and 187 inactive or decommissioned—located throughout California and bordering regions in Arizona, Nevada, Oregon, and Baja California, Mexico. As California’s official geodetic reference network under Public Resources Code (PRC) §§8850–8861, all Caltrans surveys using the California Coordinate System of 1983 (CCS83) must reference CSRN control stations or comply with CSRN specifications. The definition and use of CCS83 are governed by PRC §§8801–8819. This new realization is fundamentally tied to the International Terrestrial Reference Frame 2020 (ITRF2020) through the IGb20 coordinates adopted by International GNSS Service (IGS) Analysis Centers. All multi-year processing for this project was performed within this state-of-the-art global reference frame. Furthermore, the CSRN Epoch 2025.00 is rigorously aligned with the National Spatial Reference System (NSRS) maintained by the National Geodetic Survey (NGS). Epoch 2025.00 geodetic coordinates are transformed from ITRF2020 to NAD83(2011) using the NGS Horizontal Time-Dependent (HTDP) utility (Figure 1). The ITRF2020 coordinates (X,Y,Z) of the 1068 CSRN stations are transformed into geodetic coordinates (latitude, longitude and ellipsoidal height), using the GRS80 ellipsoidal parameters (semi-major axis, a = 6378137 m and inverse flattening, 1/f = 298.257 222 101).
CSRC submitted to the European Petroleum Survey Group (EPSG) definitions for datums, transformations, and coordinate reference systems for Epoch 2025.00 to facilitate unique terminology with associated metadata.
GPS data (phases and pseudoranges contained in RINEX data files) collected at the CSRN stations from June 10, 1992 to May 17, 2025, and about 300 global tracking stations of the IGS network were re-analyzed in the ITRF2020 reference frame. The complete set of RINEX data and metadata are accessible from the Scripps Orbit and Permanent Array Center data archive.
The latest hybrid geoid model GEOID18 published by NGS is used to interpolate geoid heights for each of the CSRN stations as the basis of Global Navigation Satellite System (GNSS) derived California Orthometric Heights (DCOH) on the NAVD 88 datum in accordance with the California PRC §§8890-8902 (California Orthometric Heights).
Figure 1. Reference frames for CSRN Epoch 2025.00 NAD83(2011).
As provided in the summary of the report, a diagram noted that the ITRF 2020 cartesian (XYZ) coordinates were transformed into NAD83 (2011) cartesian (XYZ) coordinates, and then into local topocentric coordinates (NEU) to obtain the CSRC Epoch 2025.00 NAD83 (2011) coordinates.
I downloaded the table of stations with their various coordinates and plotted the differences between the new CSRC Epoch 2025.00 NAD83 (2011) and the previous CSRC Epoch 2017.50 (NAD83 (2011) for stations that were designed as operational stations in 2025. The following plots depict the difference in coordinates between Epoch 2025.00 and Epoch 2017.50. One can see that there’s a reason that California needs to periodically update the coordinates of the California Spatial Reference Network. Some of the horizontal coordinates have changed over 300 mm or around one foot. The vertical coordinate changes are not as large, but some do shift more than 4 cm.
Note: The plots do not include newer stations with less than 6 months of solutions (no velocities estimated) and defunct stations (stations in Epoch 2017.50 but no data before January 1, 2025.
Differences in horizontal coordinates (N, E) between Epoch2025.00 and Epoch 2017.50 (northern section). Differences in horizontal coordinates (N, E) between Epoch2025.00 and Epoch 2017.50 (southern section). Differences in vertical coordinates (U) between Epoch2025.00 and Epoch 2017.50 (northern section). Differences in Vertical Coordinates (U) between Epoch2025.00 and Epoch 2017.50 (southern section)
The image below provides some statistics about the differences in coordinates between Epoch 2025.00 and Epoch 2017.50.
Notes:
(1) Only includes operational stations in 2025
(2) Does not include newer stations with less than 6 months of solutions (no velocities estimated).
(3) Does not include defunct stations: in Epoch 2017.50 but no data before January 1, 2025.
This newsletter highlighted that the CSRC has adopted a new Public Resources Code–compliant geodetic datum (reference frame) for California: CSRN Epoch 2025.00 NAD83(2011), which replaces CSRN Epoch 2017.50 NAD83(2011). The updated datum incorporates secular (linear) tectonic motions across the North America–Pacific plate boundary, transient motions (such as coseismic and postseismic deformation and fault creep), vertical land motion (subsidence and uplift), and data from new stations established since Epoch 2017.50. Additionally, the new vertical datum provides a comprehensive set of California Orthometric Heights on the NAVD88 datum for all CSRN stations.
In essence, the CSRC has released three new datums. The first is tied to ITRF2020, the second to NAD83(2011), and the third to NAVD88. Transformation parameters are available between the first two datums. The NAD83(2011)-based datum satisfies California’s Public Resources Code requirements and is the recommended standard for geodetic control in the state. The NAVD88-based datum provides GNSS-derived California Orthometric Heights of 1988 (COH88).
These new datums will be added to the European Petroleum Survey Group (EPSG) database, the worldwide standard for coordinate reference systems (CRSs) and transformations. Each will receive a unique EPSG code, making it easy to reference and use. This will ensure that CSRN Epoch 2025.00 NAD83(2011), CSRN Epoch 2025.00 (ITRF2020), and COH88 Epoch 2025.00 (NAVD88) can be seamlessly integrated into industry software.
The CSRC report also noted that NGS has released a beta version of the modernized horizontal and vertical datums for the NSRS: NGS New Datums.
Once the modernized NSRS is fully published, and in response to the needs of California’s user community, CSRC will continue working to secure resources that support its partnership with NGS and ensure ongoing compatibility with national programs.
This newsletter is going to highlight some history of the Coast and Geodetic Survey and provide the latest information on the National Geodetic Survey (NGS) new National Spatial Reference System (NSRS). First, every year my brother and I get together and travel to visit friends and relatives. He lives in Montana, and I live in North Carolina, so our yearly trips are typically 10 to 14 days long. As in all trips, I look for geodetic marks along the way. This year we traveled to coastal Maine to visit lighthouses and of course eat lobster rolls. We visited 12 Lighthouses along the Maine Coast. Lighthouses have both historical and navigational importance. The lighthouses were essential in guiding sailors through rocky shores. Portland Head Light commissioned by George Washington in 1791 is Maine’s oldest lighthouse and still guides vessels into Portland Harbor. We found NOS benchmark 841 8031 B 1979 on the grounds of this lighthouse. Pemaquid Point Lighthouse is managed by the Friends of Pemaquid Point Lighthouse, a chapter of the American Lighthouse Foundation, and remains an active aid to navigation under the ownership of the U.S. Coast Guard. We could climb up the Pemaquid Point Lighthouse, so I took a photo of the view from the top.
One of my brother’s requests was to visit the first place in the continental United States to see the sunrise. However, the location of the first place in the continental United States to witness the sunrise depends on the time of year. As indicated in the box titled “First Places to See the Sunrise in the Continental U.S.” Mars Hill is the first place to witness the sunrise in June.
841 8031 B 1979 — Mark located on grounds of Portland Head Light. (Credit: Dave Zilkoski)Pemaquid Point Lighthouse (Credit: Dave Zilkoski) View from Pemaquid Point Lighthouse (Credit: Dave Zilkoski)
First Places to See the Sunrise in the Continental U.S.
October 7 to March 6: During these months, Cadillac Mountain in Acadia National Park, Maine, holds the distinction of being the first place in the continental U.S. to see the sunrise. Its elevation of 1,530 feet and eastern location make it ideal for early morning views. reddit.com+10nps.gov+10acadiamagic.com+10
March 25 to September 18: In the spring and summer, Mars Hill in Aroostook County, Maine, takes the title. Its northeastern position allows it to catch the first rays of sunlight during this period. newengland.com+2en.wikipedia.org+2aa.usno.navy.mil+2
Around the Equinoxes: Approximately during the weeks surrounding the spring and fall equinoxes, West Quoddy Head in Lubec, Maine—the easternmost point of the contiguous U.S.—experiences the nation’s first sunrise. reddit.com+2en.wikipedia.org+2en.wikipedia.org+2
That said, when we travel together, we always recover geodetic marks, so we chose to visit Cadillac Mountain even though in June the first place is located on Mars Hill in Aroostook County.
As many of you know, I worked for NGS for 35 years so reconning monuments is exciting to me. We found six marks in a radius of about two hundred meters on Cadillac Mountain. We will talk about them in a minute.
Cadillac Mountain was important to me because from 1833 to 1898, the Coast and Geodetic Survey performed a triangulation project that extended from Calias, Maine, to New Orleans, Louisiana. The project was published as the Eastern Oblique Arc of the United States. The station Mount Desert 1856 that was located on Cadillac Mountain was part of this project. A report published in 1902 describes the Eastern Oblique Arc project and can be downloaded here.
USCGS Special Publication Number 7. (Credit: USGS)
According to the 1902 report, horizontal observations at station Mount Desert 1856 were acquired by Alexander Dallas Bache. That may not mean much to most people, but Mr. Bache was the second superintendent of the Coast Survey and was particularly important to the advancement of geodesy in the United States. As a side note, the Coast Survey was renamed the Coast and Geodetic Survey in 1878. The change reflected the agency’s expanded mission beyond coastal charting to include geodetic surveys of the nation’s interior, prompted by the growing importance of geodesy in its work.
Bache’s leadership of the U.S. Coast Survey
In 1843, Bache was appointed superintendent of the United States Coast Survey, succeeding Ferdinand Rudolph Hassler. Under his leadership, the Coast Survey expanded its missions to include hydrography, geodesy, topography, and the printing arts. He initiated geomagnetic studies, directed tide observers to make meteorological observations, and developed mathematical techniques for tide predictions and adjusting triangulation networks. Bache’s administrative skills transformed the Coast Survey into one of the foremost scientific organizations globally, providing critical data for navigation and commerce.
Alexander Dallas Bache
According to the description of Mount Desert in the 1902 USCGS report, the station was marked by a copper bolt in a ledge (see the box titled “1856 Description of Mount Desert”). The 1902 description of the station on the NGS Datasheet stated that it was a hole drilled in a rock (see the box titled “1902 Description of Mount Desert”). I’m not sure why there is a discrepancy between the two descriptions but in 1931 the Maine Geodetic Survey found the drill hole, and based on measured references to other drill holes in the area that were documented in the original description decided that it was the location of the original station (see the box titled “1931 Description of Mount Desert”). At that time, a Coast and Geodetic Survey Disk with Reference Marks were installed by the Maine Geodetic Survey.
A description of Mount Desert from 1856. (Photo: NGS) A description of Mount Desert from 1902.A description of Mount Desert from 1931.A description of Mount Desert from 1931.
As I previously stated, we found six marks in the area. The boxes titled “Photos of Mount Desert 1856 and Reference Marks” and “Photos of Other Marks on Cadillac Mountain” provide photos of the monuments we found on Cadillac Mountain. One may note that the reference mark 2 monument is in worse shape than the reference mark 1 and the Mount Desert monument. The 1944 recovery note stated that reference mark 2 was covered with roadway stone. There was not any stone covering reference mark 2 when I found it. Reference mark 1 is located behind some trees and out of sight of the path.
When I arrived at the site, there were a group of people looking at reference mark 2. I held a little lecture on the importance of geodetic monuments and how this site was first occupied in 1856; and, of course, I highlighted the importance of geodesy.
Photos of Mount Desert 1856 and reference marks. (Credit: Dave Zilkoski)
I was thrilled to stand in the very spot where Alexander Dallas Bache took geodetic measurements in 1856. [I know—people joke that I need to get a life, all because I get so fired up over geodetic monuments.]
The box titled “Abstract of Observations at Mount Desert” provides a summary of the directions from Mount Desert to the stations involved in this phase of the project. The box also includes a photo of an instrument, a 75 cm theodolite, which was used to perform the observations. The box titled “Diagram of Network Depicting Epping Base Line” provides a diagram that was included in the 1902 USCGS report.
As a side note: during the 1970s as a NGS employee, I personally coded abstracts similar to this one to convert archival data into computer-readable form in support of the North American Datum of 1983 (NAD83) project. Once all data were in computer-readable form, they were reviewed for correctness and combined in an adjustment resulting in what is known as NAD 83 (1986). See the NGS report for some details of the NAD 83 (1986)here.
The other marks we found on Cadillac Mountain included a US Geological Survey Benchmark – K 24 1934, a bent pipe denoted as Cadillac Ground, and a Department of Interior Geological Mark – Cadillac 1975. All these marks are within a 200-meter radius of each other. My understanding is that Cadillac Ground was established because Mount Desert was obstructed by trees. I have provided weblinks for those that would like more information on these marks.
After visiting more lighthouses along the Maine Coast, we traveled back to Boston and visited Waldon Pond and Thoreau’s family home. Why Thoreau you ask? In 2018, the Surveyors Historical Society and NSPS Foundation recognized Thoreau for his work as a surveyor by establishing a commemorative monument at Thoreau’s family farm.
Thoreau described surveying as a “noble employment” that kept him close to nature: “Surveying … brings you within hearing of [the birds]” – https://www.heritagesurveys.com/famous-surveyors. Surveying and geodesy are indeed noble professions; they provide the foundation for all geospatial products and services.
Photo of Commemorative Mark at Thoreau’s House. From left to right, Thoreau – A Surveyor, Thoreau Monument and drawing lines. (Credit: Dave Zilkoski)
Finally, we left Boston for Syracuse to visit my younger brother and sister. I attended the SUNY College of Environmental Science and Forestry (SUNY ESF) which is immediately adjacent to Syracuse University campus. Both of my brothers attended Syracuse University, so we like to walk around campus whenever we visit Syracuse. During our trip to the University, we recovered the monument Thornden 1934. Thornden 1934 was significant to me because I recovered this monument over 50 years ago, as part of a special project that I performed for my geodesy class.
Thornden 1934 (Credit: Dave Zilkoski)
I hope this was not too boring for you, but I real enjoy history and especially the history of the geodetic network of the United States. Today, you can use modern surveying technology to obtain a more accurate coordinate in seconds where it took days to months in the past. That is amazing!
Now, what is the latest with the modernization of the National Spatial Reference System? On June 17, NGS announced that they incorporated four groups of NSRS modernization products to the NGS beta website.
Multiple NSRS Modernization Products Published to Beta
NGS has released the following four groups of products to the NGS beta website to solicit review and feedback from stakeholders as part of the modernization of the National Spatial Reference System (NSRS): (Note: These products are not final and should not be used for anything other than review and testing.)
North American-Pacific Geopotential Datum of 2022 (NAPGD2022). This datum will replace the North American Vertical Datum of 1988 (NAVD 88) and all other vertical datums for islands in the United States. It will serve as a foundational component of the modernized National Spatial Reference System (NSRS), providing precise definitions for orthometric height (elevation). The release includes the defining grids that collectively make up the datum along with a number of supporting products to visualize the datum.
Products. All NAPGD2022 products are provided as grids for the following: GEOID2022, DEFLEC2022, GRAV2022.
Example coordinates. Coordinates and product values are computed for numerous example points throughout NAPGD2022 and provided in a table. NAPGD2022 Experience. Interactive online maps showing NAPGD2022 products for all regions that can be used on a computer or mobile device to query any location.
Maps of NAPGD2022 products. Static map images of NAPGD2022 products for all regions.New Terrestrial Reference Frames of 2022 for North America (NATRF2022), Pacific (PATRF2022), Caribbean (CATRF2022), and Mariana (MATRF2022) plates. These four geodetic reference frames will replace the North American Datum of 1983 (NAD 83). They will serve as a foundational component of the modernized NSRS, providing precise definitions for geodetic latitude, longitude, and ellipsoidal height.
Euler Pole Parameters of 2022. All of the new terrestrial reference frames are defined by transformation from the International Terrestrial Reference Frame of 2020 (ITRF2020) using Euler Pole Parameters (EPPs) that model tectonic plate rotation.
State Plane Coordinate System of 2022 (SPCS2022). A system of map projections for accessing the modernized NSRS. Zone designs have been incorporated into the following beta products and services:
Zone information tables. SPCS2022 zone definitions, example coordinate computation results, minimum and maximum coordinate values, and minimum coordinate differences with overlapping SPCS2022 zones and with other coordinate systems, provided as interactive tables that can be sorted and filtered.
SPCS2022 Experience. Interactive online maps showing distortion for all SPCS2022 zones that can be used on a computer or mobile device to get distortion at any location or to view zone definitions.
Maps of SPCS2022 zones and distortion. Static map images of SPCS2022 zone layers, number of zones, and distortion with performance statistics.
NGS Coordinate Conversion and Transformation Tool (NCAT). This version can be used to perform SPCS2022 coordinate conversions at any location for all SPCS2022 zones. Later beta versions will include the ability to transform between reference frames and vertical datums.
Products found on the NGS beta website are preliminary releases that are for testing and evaluation only; they are not final products nor do they contain any authoritative NGS data or tools. To provide feedback on any of the content on this site, please email [email protected].
Everyone should review these products and provide their feedback to NGS. That said, my April 2025 newsletter highlighted the NAPGD2022 Alpha product that was moved to the Beta site. The Beta product is like the Alpha product, but it does not have an option for an interactive computation. The Interactive Computation Option provided essential information about NAPGD2022 and would be helpful to geospatial users for obtaining a better understanding of the differences between NADGP2022 orthometric heights and NAVD 88, and GEOID2022 geoid heights and hybrid GEOID18 geoid heights. My April 2025 newsletter highlighted the interactive computation option.
Alpha interactive computation page (Credit: NGS)
As noted in my April 2025 newsletter, I downloaded the data and created my own maps to better highlight local variations. Although users can still view the original via the interactive online map, this personalized version offers clearer insights.
Here are several of my comments on the Beta products based on my preliminary review:
The NAPGD2022 difference map (NAPGD2022 minus Historical in meters) uses 25 cm intervals, which are too coarse to reveal the finer local variations between published benchmarks accurately.
The NAPGD2022 Difference map should have an overlay of the marks used in the creation of the difference map. This would allow users to identify marks in their region of interest. Clicking on a mark should link to the NGS datasheet and Passive Mark Page.
The beta page for NATRF2022, PATRF2022, CATRF2022, and MATRF2022 is not particularly helpful for everyday geospatial users. There should be an Interactive Computation Option to enter NAD83 (2011), epoch 2010 coordinates where the routine transforms the coordinates into ITRF 2020, epoch 2020, as well as estimates in the new terrestrial reference frames – NATRF2022, CATRF2022, PATRF2022, and MATR2022.
Both the State Plane Coordinate System of 2022 (SPCS2022) and The NGS Coordinate Conversion and Transformation Tool (NCAT) are good tools for users to obtain an understanding of the differences and changes in the SPCS especially for their State. That said, like above, there should be an option to enter NAD83 (2011), epoch 2010 coordinates where the routine will transform the coordinates into ITRF 2020, epoch 2020, as well as estimates in the new terrestrial reference frames – NATRF2022, CATRF2022, PATRF2022, and MATR2022. The routine does have a note that states users can transform their coordinates using HTDP, but NGS should incorporate this process in the NCAT beta product.
Note from Beta NCAT product: This beta version of NCAT supports beta State Plane Coordinate System of 2022 (SPCS2022) but not transformations between reference frames or geopotential datums. NAD 83 latitude and longitude can be used as input, but the output coordinates will differ horizontally from actual SPCS2022 by up to a few meters, depending on location (likewise for UTM and USNG). If NAD 83 ellipsoid heights are used, the linear distortion and combined factor will differ from SPCS2022 values by a small amount, within ±0.3 parts per million (ppm). To reduce these differences, NAD83 epoch 2010.0 coordinates can first be transformed to ITRF2020 epoch 2020.0 using the Horizontal Time-Dependent Positioning (HTDP) tool.
I plan to provide these comments to NGS through their feedback email process. Everyone should take time to review these products and provide your feedback to NGS. Remember, NGS placed these four groups of products on the NGS beta website to solicit review and feedback from stakeholders as part of the modernization of the National Spatial Reference System (NSRS) process. Users should review these Beta products and consider two questions:
1. Do these products provide sufficient information and detail for documenting how I will deliver my products and services under the new NSRS?
2. Do I need additional information or tools from the NGS to better understand the changes and impacts of the new NSRS?
Your feedback will help NGS improve the Beta products.
Well, it’s January 2025 and it’s almost here — that is, the release of the beta version of the new, modernized National Spatial Reference System (NSRS) – NATRF2022, PATRF2022, CATRF2022, MATRF2022 and NAPGD2022.
This newsletter will highlight some activities associated with the new NSRS. That said, this is short notice, but I would like to highlight that there is a webinar and workshop that will address the new NSRS scheduled for Jan. 9, 2025 — TRB workshop, “Navigating the Modernized National Spatial Reference System: A Geospatial Odyssey” and NGS webinar “Updates to Products and Models within the North American-Pacific Geopotential Datum of 2022.” I will provide more details on this later in the newsletter.
The modernization of the NSRS is scheduled to occur in 2025 or 2026. NGS intends to release associated tools and services within five years of the modernization. The following details from the Federal Register outline the process for the rollout of the modernized NSRS:
NGS plans to roll out components of the modernized NSRS in 2025 or 2026. As each component is released at beta.ngs.noaa.gov, it can be publicly tested with feedback provided to NGS. The testing will continue for at least six months after the final component is released on beta.ngs.noaa.gov.
Once testing is complete and all modernized NSRS components appear to be stable and correct, the Federal Geodetic Control Subcommittee (FGCS) will be asked to vote to approve the modernized NSRS (likely in 2026). If FGCS approves the modernized NSRS, NGS will publish an FRN announcing the approval of the modernized NSRS and begin a several-month process of transitioning all modernized NSRS components to the official website at geodesy.noaa.gov. During this transition, the beta website may be wiped of submitted data and no further submissions to the NGS IDB (the repository for the current NSRS) will be allowed.
Excerpt from Federal Register Notice. (Photo: Federal Register website)
What does “Only one major improvement to the current NSRS is expected during this time: ITRF2020 will be integrated in all products and services” mean? I understand that one product that ITRF 2020 will be integrated into is the NOAA CORS Network (NCN). The CORS coordinates and velocities will be updated with ITRF 2020 values. That said, NGS datasheets will still provide coordinates in NAD 83 (2011), epoch 2010.0.
As I’ve mentioned in previous newsletters, time really is running out and users need to obtain a working knowledge of the new, modernized National Spatial Reference System. For those attending the104th TRB Annual Meeting on Jan. 5-9, 2025, in Washington, D.C., there is a scheduled workshop on the modernized NSRS. The workshop is sponsored by TRB Geospatial Data Acquisition Technologies Committee (AKD70). The workshop, titled “Navigating the Modernized National Spatial Reference System: A Geospatial Odyssey,” will be held on Thursday, Jan. 9, 2025, from 9:00 am to noon, in room 202B in the Convention Center in Washington, D.C.
Thurs., Jan. 9, 2025 9:00 am to 12:00 pm Room 202B, Convention Center Washington, D.C.
This workshop will cover the following topics:
Why the NSRS is being updated
The key goals of the modernization effort
Timeline, standards and technology considerations
The Geospatial Data Act of 2018 and its impact
There will be a discussion about the replacement of the North American Datum of 1983 and vertical datums and implications for existing workflows
There will also be a discussion about use cases and practical scenarios, how to transition and how to leverage new technology and tools.
For those interested in more information on the TRB AKD70 committee, my August 2024 GPS World Newsletter highlighted activities associated with the Transportation Research Board’s ADK70 Standing Committee on Geospatial Data Acquisition Technologies.
Since the new NSRS will be introduced this year, it is time for users of the NSRS to get familiar with the NOAA Technical Memorandum NOS NGS 92 document titled “Classifications, Standards and Specifications for GNSS Geodetic Control Surveys using OPUS Projects” written by Dave Zenk and Dan Gillins, Ph.D., National Geodetic Survey, published on Oct. 23, 2024. This document provides the specifications users must adhere to when submitting GNSS projects to NGS for review and publication.
Photo: NGS website
The section below explains the purpose of the document. There are a few items that I have highlighted in the preface that users should be aware of:
The document replaces NOAA Technical Memorandum NOS NGS 58 and NOAA Technical Memorandum NOS NGS 59
Users will need to follow these specifications for all projects that will be submitted to NGS using OPUS Projects for review and publication
This publication supplements Standards and Specifications for Geodetic Control Networks issued in September 1984 (Bossler 1984).
This publication replaces NOAA Technical Memorandum NOS NGS 58 Guidelines for Establishing GPS-Derived Ellipsoid Heights (Standards: 2 cm and 5 cm), Version 4.3 (Zilkoski et al. 1997) and also replaces NOAA Technical Memorandum NOS NGS 59 Guidelines for Establishing GPS-Derived Orthometric Heights (Zilkoski et al. 2008).
This publication provides classification, standards, and specifications for GNSS geodetic control surveys that use Global Navigation Satellite Systems (GNSS), which will be submitted to NGS using OPUS Projects for review and publication. These types of surveys were not well-established by the dates of the 1984, 1997, and 2008 publications, nor did OPUS Projects exist. In addition, since 2008 GNSS technology has improved and considerable research has been done into the best practices regarding these surveys and the analyses of achievable results (e.g., Allahyari et al. 2018; El Shouny and Miky 2019; Gillins and Eddy 2015, 2017; Gillins et al. 2019a; Gillins et al. 2019b; Jamieson and Gillins 2018; Park et al. 2018; Schenewerk et al. 2016; Soler and Wang 2016; Wang and Soler 2013; Wang et al. 2017; Weaver et al. 2018). That research supports this publication.
This publication is specifically limited to supporting OPUS Projects (version 5.x), the current North American Datum of 1983 (NAD 83), the North American Vertical Datum of 1988 (NAVD 88) and other current vertical datums that are officially recognized by NGS. Future versions of OPUS Projects and future datums will require revision of this publication.
I highlighted some important sections of the April 2023 webinar in my May 2023 newsletter. Future newsletters will address the specifications in more detail, but I would encourage readers to download the NGS 92 document and the April 13 webinar and slides.
On Dec. 18, 2024, NGS sent an email to individuals on NGS’s listserv informing them that they have made several updates to the NAPGD2022 products and that these updates are now available on the NGS alpha site.
NGS Dec. 18 newsletter. (Photo: NGS website)
To explain the product updates, NGS has scheduled a webinar for Jan. 9, 2025, to discuss the North American-Pacific Geopotential Datum of 2022 (NAPGD2022).
As previously stated in my newsletters, users should obtain a working knowledge of the new, modernized National Spatial Reference System. NGS publicly given presentations that have been collected for public viewing can be downloaded here.
I would like to wish everyone a Happy New Year and a year filled with exciting opportunities.
On Sept. 10, the GeoGov 2024 Summit hosted a panel discussion between NGS and other federal and industry leaders on the modernized National Spatial Reference System (NSRS). High-level management and leadership officials attended the conference, which was a great place to network and collaborate with federal agencies.
Panel session on NSRS modernization.
As you can see from the announcement, the panel members represented a wide range of users of the NSRS. They were asked to address the following four topics based on their perspective of the rollout of the new, modernized National Spatial Reference System:
Benefits of Modernization
Challenges of Modernization
Opportunities Provided by Modernization
Next Steps in Collaboration
As one would expect, there was a wide range of responses based on the individual panel’s perspective of what the new, modernized NSRS means to their products, services and constituents. Even though there were many responses based on the individual panel’s perspective, there were many common ideas. This newsletter will highlight some of the bullet points presented by the panel members during their presentations. I attempted to combine similar statements for every topic under a common theme.
Summary of Benefits of Modernization
A unified four-dimensional system will finally provide a sustainable spatial reference frame for managing the state’s geospatial resources.
Combining of horizontal and vertical datums in one system
Improved spatial data quality – both horizontal and vertical
Simplification in which vertical reference frame and GEOID to use in local areas with the new NAPGD2022
Improved accuracy of the horizontal and vertical coordinates
A common “language” or framework for spatial data
Greater consistency in non-CONUS areas like AK, Hawaii, PR, and USVI
We can write NSRS requirements into any task order for acquisition
Additional uniformity for surveying practitioners
Better spatial data sustainability
The unification of marine and terrestrial geoids is important for managing our valuable coastal resources (all heights should be geoid based)
Closer integration with tidal datum information
Improved height information will enable us to provide the most accurate data possible
Direct relationship to ITRF2020 offers the ability to deliver the intra-frame deformation model through real-time networks
The introduction of reference epochs on NGS geodetic survey benchmarks and the time-dependency of the datums
The ability to more easily link the data to ITRF
Expansion of low distortion projection (LDP) systems
Lack of metadata within historical information to adapt to the new datum
Ensuring data fidelity, now and always! (METADATA)
People and processes; not technology
Users with lack of understanding of a time-dependent datum
Surveyor making time to learn about new datum
Understanding the impact of the new system to your products and services
How do we convince them to effectively transition all their historic data to the latest reference system?
Confusion among end users in understanding geodetic terminology and time-dependent way of perceiving coordinates
Adequate understanding by all stakeholders
Degrading coordinates and heights can impact reliability over project lifespans (NGS may not be able to respond to natural changes and emergencies)
Maintaining an accurate deformation model for use by many geospatial users in their specific workflows
Updating specifications on ground surveys for lidar and ortho projects that are processed through OPUS (How do we better educate our team and partners on what can be considered accurate for those observations)
Updating of existing surveying equipment to include new datum
Potential confusion in reported accuracy as it relates to changes in epoch vs. actual error of the equipment (ground-based or aerial/satellite) and the approach used to measure the feature
Transformations to new datums may incur costs if partners do not want to “modernize” data (Potential of needing two copies of data delivered)
Will need to develop policy deciding if we “modernize” all our older/existing data, or just start with the new NSRS at a certain point in time
Need operational software that reprojects/transforms data – especially large, bulk features (e.g., lidar point clouds)
Combining legacy data with modern data can lead to loss of data fidelity and often difficult to recognize changes to the data
Many challenges were mentioned, but I found it interesting that panel members highlighted issues with the user’s lack of understanding of the new system’s impact on their products and services. It is about people, not the processes or new technology. This was not surprising to me because this was an issue when NGS implemented the North American Vertical Datum of 1988 (NAVD 88). I know this firsthand because I was the NAVD 88 Program Manager while working for NGS. Surveyors and mappers are used to dealing with new technology and datum changes. Still, management and leadership have different issues that need to be addressed for new technology and datum changes. Hopefully, the management and leadership that attended the GeoGov 2024 Summit will start identifying how their products and services will be affected by the new NSRS and developing implementation plans.
Summary of Opportunities Provided by Modernization
Increased collaboration between private entitles and public agencies
Providing better service
Reducing cost
Improving safety and welfare
Expanding innovation
More reliable data for monitoring trends in infrastructure
Providing efficient and cost-effective tools and processes for users to update their mapping products to the new reference system
More accurate data collection/dissemination to benefit the public
More uniformity of data collection between surveyors
Improved reliability of advanced positioning built on the new NSRS
Improved heights for flood mapping products for forecasting, infrastructure planning and design, and accessibility using GNSS
Facilitates integration of tidal datum, critical to coastal science and industry
Allows for unification with SAR imagery and satellite altimetry, improving earth observations and mapping products
Improved Change Detection estimations
Better metadata descriptions for understanding times of collections
Increased vertical data for monitoring existing conditions
More accurate representation of the Earth’s surface over time as it lates to coastal change (sea level rise, flood modeling, coastal erosion, etc.)
Compensating for workforce attrition
As in any new paradigm, there are opportunities for increased collaboration between users and the development of new products and services. The panel members highlighted opportunities to provide better service to customers, develop more efficient and cost-effective tools for users and improve coastal change detection models.
Next Steps in Collaboration
Cross promotion of new datums within likeminded professions
Recruitment into geospatial professions
Increased awareness of the importance of the geospatial professions
New or expanded collaborations across professions
Leveraging non-federal resources and their active user communities spanning surveying, geophysical science, regional governmental agencies, industry, and academics
Working together to convince state/local agencies to adopt the new datums
Working with geospatial societies (NSPS, AAGS, ASPRS, URISA,etc.) for impact awareness
Working together to identify the new NSRS impact on your products and services
Guidance from professional organizations and societies
Implementation of tools and processes for datum conversion for large remotely-sense datasets for more effective data analysis for reporting climate change
Under the next steps in the collaboration section, promoting the new reference frames with other geospatial professionals was mentioned as an opportunity to leverage resources and expand the understanding of the new NSRS’s effect on users’ products and services. That is, increasing the number and types of stakeholders and constituents affected by the new reference frames will increase awareness of the new NSRS.
Joint Actions to Promote a Smooth Transition
Promoting awareness to non-technical leadership within AEC industries
Provide examples of the potential for a datum upgrade (smart cities, digital twins, autonomous transportation.)Educate allied professionals (e.g. engineers, contractors, operators.)Develop unified messaging for practitioners (e.g., best practices/standards.)
Focus on the education component and benefits of the new datum.
Act now to develop a specific plan and resource allocation to implement the new reference frame
Helping develop appropriate standard metadata/STAC templates and information
Provide open-source tools to the private sector to enable datum conversion and an open discussion forum.
For a smooth transition of the new NSRS, it is important to identify actions required for implementation. Promoting awareness to leadership is critical for the implementation of any new system. In the case of the new NSRS, it is essential for federal agencies to get engaged in the process now. I was pleased to hear that panel members mentioned that it is vital for federal agency engagement through the Federal Geographic Data Committee (FGDC) and the Federal Geodetic Control Subcommittee (FGCS) to be compliant with the Geospatial Data Act of 2018 (GDA 2018). These federal agencies must develop plans and allocate resources to implement the new NSRS.
As previously stated, high-level management and leadership attend the GeoGov 2024 Summit conference. It is a great place for networking and collaborating within federal agencies and for better understanding the issues associated with implementing the new, modernized NSRS.
Technology and tools are essential for the development of the new, modernized NSRS. That said, understanding how the use of technology and tools meet the users’ requirements is necessary for implementation.
Some users trust NGS models and tools without following the appropriate procedures. Standard operating procedures are used in a workflow to help meet users’ project requirements. In my opinion, understanding the impact of the new system on a specific product and service is the most important part of implementing the new NSRS. Documenting the workflow used to create a product and service and then using this information to develop standard operating procedures that use the appropriate tools and procedures will help implement the new, modernized NSRS.
In less than a year, NGS will be finalizing the new terrestrial reference frames and geopotential datum. Time really is running out and users need to obtain a working knowledge of the new, modernized NSRS.
My previous column highlighted that orthometric heights in NAPGD2022 will be defined through ellipsoid heights and a geoid model, such as GEOID2022. Therefore, changes in the geoid model will be very important to users estimating orthometric heights using GNSS. I briefly described the geophysical reasons for changes in the geoid that affect the orthometric height of a mark.
For the past four years, I have discussed in my columns the tasks associated with the new, modernized 2022 reference frames. It’s now the middle of 2022, so where are the new reference frames? Well, on June 9, Dru Smith, NSRS modernization manager for the National Geodetic Survey (NGS), provided an update on the status of the modernization in a webinar. The Powerpoint slides and video of the presentation can be downloaded from the NGS website under the following title: It’s 2022…Are You Done Yet? I will highlight some of the items from the webinar, but I encourage everyone to download the video and listen to the webinar.
First, Smith mentioned that NGS will be providing new types of coordinates. The NGS denotes this as a two-track approach to coordinates: Reference Epoch Coordinates (REC) and Survey Epoch Coordinates (SEC). See the box below.
New types of coordinates (Image: NGS June 6 webinar)
Reference Epochs Coordinates (REC) are defined in NGS Blueprint for the Modernized NSRS, Part 3 as coordinates computed by NGS in an adjustment project to estimate the coordinates at one of the official reference epochs that NGS will define in 2025. RECs are similar to coordinates computed by NGS in a nationwide adjustment project such as the National Adjustment of 2011 (see the box below).
NAD 83 (2011) epoch 2010.00 coordinates (Image: NGS)
NGS has not determined what data will be included in the first iteration of RECs. For the 2020.00 project, the current cutoff date for incorporating data is Dec. 31. Users can submit the data to NGS via OPUS projects and the OPUS-Share tool. To increase the submission of GNSS observations on marks, NGS has developed a beta OPUS-Projects 5.0 webtool that will allow real-time kinematic and real time network (RTK/RTN) observations to be submitted.
As previously mentioned, at this time, the NGS has not determined the cutoff for the earliest data to be included in the determination of the 2020.00 RECs. The agency will be conducting experiments to determine the appropriate cutoff date. These coordinates will require an intra-frame velocity model (IFVM) to generate the RECs at the specific reference epoch.
As of February 2021, based on NGS’ Blueprint for the Modernized NSRS, Part 3, version February 2021, the following is the agency’s policy with regard to RECs:
For a given mark and a given reference epoch, the REC will never be changed–except to correct a blunder.
This does not prevent NGS from adding new RECs
on points with new data that have not yet had an REC computed
for marks that do not have an REC in the most recently passed reference epoch, a new REC can be computed and added to the NSRS.
Survey epoch coordinates (SECs) are defined as coordinates computed by NGS at a specific survey epoch. Users will submit their data and its metadata to NGS, and NGS will then check, adjust and define the coordinates at one “survey epoch.” These coordinates will be “part of the NSRS,” Smith said. NGS is computing coordinates in this manner to provide the best estimate of the coordinates at any mark at a specific moment in time, which is very important in areas influenced by crustal movement.
So, how will NGS process and generate these SECs?
Survey epoch coordinates (SECs) are designed to provide time-dependent geodetic coordinates. Therefore, NGS has to choose some time span in which all observations will be processed together to yield a single SEC of a mark. NGS denotes this time span as a “geometric adjustment window.” NGS wants the adjustment window to be short enough so that movement of a mark did not occur between repeat observations (or was small enough to be ignored) and long enough for users to efficiently and effectively collect redundant observations for submission to NGS (see the box below).
One or more GNSS occupation(s) over a single mark will be processed into one survey epoch coordinate when all occupations take place within one geometric adjustment window.
If a user submits two occupations on one mark, but they happen to fall in two consecutive geometric adjustment windows, NGS will use them to create two distinct survey epoch coordinates. Each SEC will be based on one occupation.
Future columns will provide more explanation about this concept of a geometric adjustment window and how NGS will process the data to generate survey epoch coordinates.
NGS is developing models and tools for users to submit data to NGS to compute coordinates — including OPUS coordinates, reference epoch coordinates and survey epoch coordinates. Figure 9 from Blueprint for the Modernized NSRS, Part 3, version February 2021, is a schematic that shows the flexibility NGS is building into an OPUS-type webtool. Basically, if users follow NGS guidelines and rules, and submit their data to NGS, then NGS will compute and publish REC and SEC coordinates (see the blue outline in the box below). If users only want to compute OPUS coordinates, then they can use NGS’s webtool without submitting the data to NGS (see the red outline in the box below).
Building flexibility into OPUS (Image: NGS)
Dru Smith’s June 9 update on the status of the modernization provided a mockup of how users will be able to retrieve data using their web browsers — a prototype is being developed. The data will also be available in downloadable form such as an XML file for users to input the data and metadata into their programs or databases. I recently discussed some of this material at seminars I presented at the Florida Surveyors and Mapping Society’s 67th annual conference held in Palm Beach Gardens. The participants were very interested in the prototype, but really wanted to learn more about the format and process of the downloadable XML files. I’m sure future NGS webinars will address this topic. I emphasized to the group that they should watch the entire presentation and provide feedback to NGS. As mentioned above, Powerpoint slides and video can be downloaded from the NGS webinar website.
The boxes below highlight a few of the options NGS is considering. The box “Data Delivery – Prototype” is an example provided by Smith during his webinar. It should be noted that the images of the prototype are not included in the downable slides, but they are part of the video. The images presented in this column are screen captures from the video.
Data delivery prototype. (Image: NGS)
The box below provides some of the basic information of a mark, such as its PID, name, stability, GNSS usable code, setting and the latest recovery information. Again, this is a prototype, so users should feel free to send feedback to NGS. NGS wants to generate a usable product, and is interested in user feedback.
Primary information prototype. (Image: NGS)
As previously stated, NGS is implementing a two-track approach to coordinates: publishing REC and SEC. The box below provides the REC information of a mark when a user clicks the “Show” button. As shown in the diagram, the reference frame and epoch are provided, as well as the geometric coordinates (latitude, longitude, ellipsoid height) and geopotential coordinate information (NAPGD2022 orthometric height and geoid height).
NGS provides an option for individuals who want the geometric coordinates in the X, Y, Z format (see the box below). Remember, this is only a mockup of a prototype, to give us an idea of the direction NGS is going with its data delivery system in the new, modernized 2022 NSRS.
REC Shown in X,Y,Z. (Image: NGS)
Similar to the REC, the prototype includes SEC. For a mark, the latter are different from the former because SEC are computed at the epoch of the survey observations (see the box below).
The box titled “SEC in CATRF – Prototype” is an example of a mark in the CATRF reference frame and the survey epoch of 2012.94. As indicated in the diagrams, users will be able to select the reference frame (ITRF, NATRF, CATRF, PATRF and MATRF) and the survey epoch.
SEC in CATRF – Prototype
Option to Select Survey Epoch
Options to select reference frame (Images: NGS)
Another feature of the data delivery system is that it provides plots of a mark’s survey epoch coordinate values at different epochs. In the example shown in the box below, the plots provide values of a mark’s latitude, longitude and ellipsoid heights based on each survey epoch data. The user can select various reference frames of the mark to understand the change based on the reference frame.
Coordinate plots in ITRF prototype. (Image: NGS)
The box below clearly shows a slope in the changes in coordinates based on survey epochs, especially in the longitude. This is the plate rotating in time. You can see the changes in latitude, longitude and ellipsoid height in the NATRF reference frame for the same mark. The latitude and longitude plots do not show a slope because the plate rotation is removed using a model to change from the ITRF reference frame to the NATRF reference frame. That said, the ellipsoid height plots look the same because the rotation model does not change the ellipsoid height.
Coordinate plots in NATRF prototype. (Image: NGS)
The prototype also provides maps, photos and descriptive text of the mark.
Map and photos of a mark in the prototype. (Image: NGS)
Descriptive text prototype (Image: NGS)
Some of this data delivery output may seem familiar to users who have used the NGS beta routines (see the box below).
Beta Routines
Beta routines (Image: NGS)
For example, the Passive Mark Page Webtool provides the coordinate information for a mark. My October 2020 column described the tool is detail. See below for an example of the passive mark tool.
Beta Passive Mark of KK1531 (Image: NGS)
The NGS Beta Map routine enables users to link to NGS datasheets, the passive mark tool and mark recovery, as well as connect to OPUS Shared Solutions and the NOAA CORS Network. See below for an example. It also provides a measuring tool, multiple basemaps and the ability to export data. My December 2021 column described the NGS Beta Map in detail.
Example of NGS Beta Map Routine for KK1531 (Image: National Geodetic Survey)
Only three years remain before the release of the new, modernized NSRS. I encourage everyone to try all of the beta products, and download Dru Smith’s June 6 webinar for a better understanding of the agency’s current thoughts on how it will provide data to users in the new, modernized NSRS. As for all the NGS beta products, the agency would like users to try the tools and provide feedback on what they liked and what they didn’t like, as well as any additional information you need or would like to see. The NGS is trying to develop tools useful to everyone, but that won’t be possible unless they hear from users.
The following statement on NGS beta products explains how to provide feedback and why it is important:
“This is a beta product. NGS is interested in your feedback concerning its function and usability as well as how users would like to interact with NGS datasheet information in the future. Email us at [email protected].”
My April column addressed the vertical movement at the NOAA CORS Network (NCN). The values at the sites indicate the potential movement of marks in the area of the CORS. The rates are based on GNSS data and have an estimate of error associated with them.
As I mentioned in my previous column, I’m not sure how the National Geodetic Survey (NGS) will address the vertical movement effects in the new, modernized National Spatial Reference System (NSRS). That said, NGS will be monitoring the CORS and looking for trends to help describe the vertical movement at the CORS. These trends are an indication of what may be happening in that area.
As stated in previous columns, orthometric heights in NAPGD2022 will be defined through ellipsoid heights and a geoid model, for example GEOID2022. In addition to the movement of individual marks due to crustal movement, there are geophysical reasons for changes in the geoid that affect the orthometric height of a mark. Therefore, changes in the geoid model will be very important to users estimating orthometric heights using GNSS.
As stated in the NOS NGS 64 report, NGS has set a goal of maintaining geoid accuracy at 1 centimeter (1 standard deviation) in both absolute and differential geoid undulations. The box titled “Figure 13 from NOS NGS 64 Report” depicts an estimate of the secular change in the geoid. As indicated in the plot, the changes are very small, ranging from -1.25 mm/year to 1.5 mm/year.
What I find interesting is the small negative change in the southeastern United States. There are other drivers for geoid changes. This column will address some of these changes and what they mean to users.
Secular geoid change
Figure 13 from NOS NGS 64 Report (Image: NGS)
As mentioned in many of my articles, the new, modernized NSRS has a time-dependent component. This includes the geoid model. Table 5-1 from NOS NGS 64 report are examples of some of the physical processes being investigated by NGS to account for changes in the geoid. (See the box titled “Some of the geophysical drivers of geoid change.”)As mentioned in the NOS NGS 64 report, the magnitudes in red have already been determined to be too small for NGS to model. The examples highlighted in yellow have magnitudes that are significant and NGS will attempt to account for these changes to the geoid.
Table 5-1: Some of the geophysical drivers of geoid change
NGS classifies the changes in the geoid in three different groups: Shape Change, Size Change, and W0 Change. The box titled “The Groups of Geoid Change” provides NGS’s definition and explanation of the terms.
The groups of geoid change
NGS’s report on their Geoid Monitoring Service (GeMS) program provides figures that depict an estimate of the secular geoid rate trend based on the NASA GSFC mascon model. See the boxes titled “Estimate of Geoid Rate Over CONUS” and “Estimate of Geoid Rate Over Alaska.” For more details on GeMS, download the report NOAA Technical Report NOS NGS 69: A Preliminary Investigation of the NGS’s Geoid Monitoring Service (GeMS), and read my December 2019 Survey Scene column. The secular geoid rate trend is an example of the geoid changing its shape, but not the W0 value. What this means is that the local geoid undulations will change, but the overall size of the geoid will not.
Estimate of geoid rate over CONUS
Figure 32: Geoid rate over CONUS based on the GSFC mascon model [mm/yr] (Image: NOAA)Estimate of geoid rate over Alaska
Figure 33: Geoid rate over Alaska from GSFC mascon model [mm/yr] (Image: NOAA)These changes in the geoid are fairly small values (+/- 1.3 mm/year), but they will accumulate over a decade. As previously stated, NGS’s goal is to maintain geoid accuracy at the centimeter level (1 standard deviation) in both absolute and differential geoid undulations. In my February 2022 column, I discussed how coordinates change because Earth’s surface is moving due to the movement of major tectonic plates. It’s fairly obvious how the tectonic shift affects horizontal coordinates, but earthquakes and volcanic eruptions can also cause large shifts in vertical coordinates.
In recent history, on May 18, 1980, geologists watched in awe as Mount St. Helens erupted in a gigantic explosion. After the eruption, the volcanic cone of Mount St. Helens had been completely blasted away; the peak, which was at an elevation of 9,677 feet (2,950meters) was changed to a horseshoe-shaped crater with an elevation of 8,363 feet (2,549 meters). Extreme crustal movements such as the Mount St. Helens eruption can change the shape of the geoid. As explained in my April 2022 newsletter, NGS understands this and is attempting to manage the changing coordinates by providing a time-dependent component to a mark’s ellipsoid height, but there is also a time-dependent component to the geoid that affects the mark’s orthometric height.
Ring of Fire
Image: National Ocean Service
The “Ring of Fire” map highlights earthquake activities around the world. As indicated in Table 5.1, earthquake or volcanic eruptions can change the shape of the geoid. Of course, they also can change the height of a mark due to crustal movement, which would typically be larger than the change in the geoid height. The amount of movement would be due to the size and magnitude of the event, but even small earthquakes could cause a change in the height of a mark located near the event. Earthquakes are occurring all over the world every day.
Earthquakes with large magnitudes are highlighted by news media outlets, but ones with smaller magnitude typically are not highlighted. The four figures below provide examples of earthquakes that have occurred over 30 days. This information can be obtained from the United States Geological Survey (USGS).
Earthquakes during the past 30 Days Date: May 20, 2022
Image: USGS
Earthquakes in the lower 48 during the past 30 days Date: May 20, 2022
Image: USGS
Earthquakes in eastern United States in the past 30 days Date: May 20, 2022
Image: USGS
I found the large number of earthquakes that occurred in Oklahoma in just 30 days to be very interesting. This isn’t something that I thought occurred in the eastern region of the United States.
Earthquakes in Oklahoma during the past 30 days
Date: May 20, 2022
Image: USGS
The image below depicts earthquakes that have occurred in Oklahoma in the past five years. They are fairly small in magnitude, but what is the cumulative effect on the geoid in the region, as well as changes to the orthometric heights of marks due to crustal moment in the region? This is why it is important for the new, modernized NSRS toimplement time-dependent coordinates.
Earthquakes in Oklahoma in the last 5 years Dates: 2017 to 2022
Image: USGS
To better understand the changes to the geoid, NGS performed a survey in Alaska to obtain geodetic data as part of its GeMS program. On May 12, 2022, Kevin Ahlgren, a geodesist at NGS, described in a webinar the observations collected and some of the results.
The presentation provided an overview of a field campaign performed in support of the GeMS program and a time-dependent geoid model. The campaign included static GNSS, relative gravity, and deflection of the vertical techniques on 50 stations in Alaska. The webinar was can be downloaded.
I encourage everyone to download the presentation. The change in the geoid due to geophysical drivers is small, but if the new, modernized NSRS is going to include time-dependent coordinates, then changes in the geoid must be accounted for. For demonstration purposes, NGS provides an example of the time-dependent geoid change in the xGEOID20 webtool. The box below, “xGEOID20 interactive computation output,” is an example of using this tool. The two stations are located in Alaska. As indicated in the output from the tool, the change in the geoid is 8 mm in five years. Again, NGS’s goal is to maintain geoid accuracy at the centimeter level (1 standard deviation) in both absolute and differential geoid undulations. These small changes can become significant over time.
xGEOID20 interactive computation output
Note: DN is the time-dependent geoid change computed between user inputted epoch (t) and t. (Image: NGS)
The last geoid change group that I’ll highlight has to do with the change in the gravity potential (W0) value that defines the model. The NOS NGS 64 Report states that the standing definition of the geoid, as adopted and used at NGS, is the following:
The geoid is the equipotential surface of the Earth’s gravity field which best fits, in a least squares sense, global mean sea level.
As stated in the NOS NGS 64 report, over a century of sea-level measurements imply that global mean sea level (GMSL) was rising at a rate of approximately 1.7 millimeters per year and was rising at a rate of 3.2 millimeters per year between 1993 and 2010 (IPCC, 2014). If NGS is going to define the geoid as theequipotential surface of the Earth’s gravity field that best fits, in a least squares sense, global mean sea level, then the geoid in the new, modernized NSRS must change when the GMSL exceeds a certain threshold.
Again, NGS’ goal is to maintain geoid accuracy at the centimeter level (1 standard deviation) in both absolute and differential geoid undulations. What this means is that as GMSL rises, the value of gravity potential which best fits to GMSL (called W0) will also change. In other words, the surface which was called “the geoid” and had W=W0in 2022 will no longer be the geoid. A new value of W0 (W0new) is chosen, and “the geoid” would now be the surface W=W0new.
So, what does this really mean to users? The NOS NGS 64 Report states on page 37:
“NGS and the Canadian Geodetic Survey have jointly adopted the value of 2.0 m^2/s^2 as the replacement threshold for a new geoid model (and new geopotential datum). This represents approximately 20 centimeters of GMSL (and thus geoid) rise. At the current rate of sea-level change of about +3 millimeters per year (IPCC, 2014), this means NGS expects to replace NAPGD2022 in approximately 60 to 70 years.”
Therefore, this should not be a major concern of users for a long time.
This column highlighted that orthometric heights in NAPGD2022 will be defined through ellipsoid heights and a geoid model, for instance GEOID2022; and therefore, changes in the geoid model will be very important to users estimating orthometric heights using GNSS. It briefly described the geophysical reasons for changes in the geoid that affect the orthometric height of a mark.
If NGS is going to meet the goal of maintaining geoid accuracy at 1 centimeter (1 standard deviation) in both absolute and differential geoid undulations, they will have to address changes in the geoid. The secular changes in the geoid, as indicated in Figure 13 in the NOS NGS 64 report, are very small, ranging from -1.25 mm/year to 1.5 mm/year. Once again, these are small changes to the geoid, but they will accumulate over time, and that is why NGS is including time-dependent coordinates in the new, modernized NSRS.
My February column explained why it is important to account for horizontal movement of marks everywhere, and not just in areas influenced by active crustal movement due to earthquakes such as Southern California.
It provided information about the NOAA CORS Network (NCN) rates of movement based on International Reference Frame of 2014 (ITRF2014) coordinates and horizontal velocity information. It highlighted reports from the National Geodetic Survey (NGS) that describe models that will facilitate users transferring coordinates between reference frames and dealing with intra-frame movement between marks based on surveys performed at different epochs.
NAPGD2022 orthometric heights will primarily be accessed through GNSS technology.
As I stated in my February column, this is not just a horizontal positioning issue. In this month’s column, I address estimates of vertical movement that will have to be accounted for in the new, modernized National Spatial Reference System (NSRS).
NAPGD2022 will provide gridded models for North America (that includes CONUS, Alaska, Hawaii, the Caribbean, Canada, Mexico, Central America and Greenland), American Samoa and Guam/Commonwealth of Northern Mariana Islands (CNMI). My previous columns have described the NAPGD2022 in detail. The revised NOS NGS 64 report mentioned that NAPGD2022 will be built upon ITRF2020. It states that NAPGD2022 will operate equally well in any of the four new terrestrial reference frames developed as part of the new, modernized NSRS in 2022.
As I stated in previous columns, orthometric heights in NAPGD2022 will be defined through GNSS ellipsoid heights and GEOID2022. This means NAPGD2022 orthometric heights will primarily be accessed through GNSS technology. GEOID2022 will be defined in a manner that best fits global mean sea level at the epoch of NAPGD2022.
As in my previous column, to better visualize the potential size of the vertical movement, I used the CORS ITRF2014 coordinates and velocities from the NGS website to create plots depicting the upward velocity (Vu) values for CORS that are designated as operational and have computed velocities. [Note: I use the term upward because that is how it is reported on the NGS CORS website under the tab labeled “position and velocity.” The term upward velocity means movement in both directions — negative is downward and positive is upward.] The box below shows maximum, minimum, average and standard deviations of upward velocity values for each state and territory of the United States.
Table of ITRF 2014 Upward Velocities of US CORSs
The upward velocity values are not as systematic as the horizontal velocity values, and they are significantly smaller. I have highlighted the average value velocity column. As indicated in the table, the values vary from state to state, but they are all small relative to the horizontal movement values. (See my previous column for plots depicting the horizontal values.)
What is interesting is the range of values in some states. For example, Alaska and California have a very large range — understandable because of the active earthquakes and other movement that occur in these states. Also, Louisiana and Texas have a very large range due to local subsidence.
I decided to highlight the values for the conterminous United States (CONUS) in two separate plots. The box “Upward Velocities (Vu) Between +/–5 mm/year in CONUS” depicts upward velocities (Vu) between +/–5 mm/year in CONUS. The box “Upward Velocities Greater than Absolute Values of 5 mm/year in CONUS” depicts upward velocity values greater than +/–5 mm/year.
Upward Velocities (Vu) between +/- 5 mm/year in CONUS
Image: Dave Zilkoski
It’s obvious that most of the vertical movement values are between +/–5 mm/year in CONUS. There are some large values in California, Louisiana and Texas. This is highlighted in both plots.
Upward Velocities (Vu) Greater than Absolute Values of 5 mm/year in CONUS
(Image: Dave Zilkoski)
As indicated in the plots, some of the values exceed 10 mm/year. In five years, the heights of marks in these regions could potentially change by 5 cm. An example of the potential subsidence in the Houston-Galveston, Texas, region is depicted in the box below. As indicated in the plot, some marks are subsiding greater than 2 cm/year. That means in five years the marks in that region could have subsided more than 10 centimeters.
Estimate of Subsidence in the Houston-Galveston, Texas, Region
The box below depicts the values in Alaska. Most of these values indicate that the marks are uplifting. Some of these values exceed 10 mm/year. Once again, height coordinates in some regions will potentially change 5 cm in five years. I generated a separate plot for the southeastern region of Alaska. (See the box titled “Upward Velocities (Vu) in Southeastern Alaska.”)
Upward Velocities (Vu) in Alaska [All Values]
Image: Dave Zilkoski
Upward Velocities (Vu) in Southeastern Alaska [All Values]
Image: Dave Zilkoski
As I did in my previous columns, I prepared several plots that depict the upward velocities in various regions of the United States. See the boxes below for North Carolina, Missouri Southwest U.S. The plots indicate that the magnitude of the vertical movement varies from state to state, as well as within the states.
CORS ITRF 2014 Upward Velocities (Vu) in Missouri [All Values]
Image: Dave Zilkoski
CORS ITRF 2014 Upward Velocities (Vu) in Southwest U.S. [All Values]
Image: Dave Zilkoski
CORS ITRF 2014 Upward Velocities (Vu) in Southwest U.S. [Values Between +/- 5 mm/year]
Image: Dave Zilkoski
I also generated plots that separately depict the positive and negative upward velocities for the conterminous United States. There are more negative upward velocity values than positive values.
CORS ITRF 14 Positive Upward Velocities (Vu) in Conterminous U.S. (Values between 0 and 5 mm/year)
Image: Dave Zilkoski
CORS ITRF 2014 Negative Upward Velocities (Vu) in Conterminous U.S. (Values between -5 and 0 mm/year)
Image: Dave Zilkoski
The table below provides the number of CORS with negative upward velocity values and the number of CORS with positive values for every state and territory of the United States. I have highlighted the states and territories that have more positive values than negative values. As you can see, only six states have more positive upward velocities than negative values. Four of the six states are in Northeastern United States.
Table of ITRF 2014 Positive and Negative Upward Velocities for United States
So far, this column has only addressed the vertical movement at the NCN CORS. The values at the sites indicate the potential movement of marks in the area of the CORS. The rates are based on GNSS data and have an estimate of error associated with them.
I’m not sure how NGS will address the vertical movement effects in the new, modernized NSRS. That said, NGS will be monitoring the CORS and looking for trends to help describe the movement at the CORS. These trends will be an indication of what may be happening in the area.
In addition to the movement of individual marks, there are geophysical reasons for changes in the geoid. As I stated in previous columns, orthometric heights in NAPGD2022 will be defined through ellipsoid heights and GEOID2022. Therefore, changes in the geoid model will be very important to users estimating orthometric heights using GNSS.
As stated in the NGS 64 report, NGS has set a goal of maintaining geoid accuracy at 1 centimeter (1 standard deviation) in both absolute and differential geoid undulations. Figure 13 from the NGS 62 Report depicts an estimate of the secular change in the geoid. As indicated in the plot, the changes are very small, ranging from –1.25 mm/year to 1.5 mm/year.
What I find interesting is the small negative change in the southeastern United States. There are other drivers for geoid changes. Future columns will address some of these changes and what it means to users.
Figure 13 from NOS NGS 62 Report
Image from NGS website: Blueprint 2 Revised NOAA_TR_NOS_NGS_0064.pdf
Figure 13 – Secular Geoid Change
Lastly, I’d like to highlight a new service from NGS: “NGS Webinar Series Certificates of Attendance.” See the box titled “Ways to Earn a Certificate of Attendance.” Basically, users can earn certificates by viewing a webinar after it has been posted by NGS. This is very useful for users who could not attend the original webinar. I encourage all users to check out the site to find out more information about the new service.
Ways to Earn a Certificate of Attendance
Image from NGS website: https://geodesy.noaa.gov/web/science_edu/webinar_series/certificates.shtml