Pub. 13 2018 Issue 1

www.ucls.org 28 Issue 1 2018 / UCLS Foresights GEOID18v2.2 - GEOID12B meters -0.32 - -0.10 -0.10 - -0.05 -0.05 - -0.02 -0.02 - -0.01 -0.01 - 0.01 0.01 - 0.02 0.02 - 0.05 0.05 - 0.10 0.10 - 0.20 will improve future models for transforming vertical data in your state or local area to the future geopotential datum. For the bench marks included in the priori - tized list, NGS recommends contributing in two ways: 1. Attempt to locate the marks on the list and submit a mark recovery through DS World. Check this NGS page for more in - formation on mark recovery. 2. Collect 4 or more hours (more is better) of GNSS data on the mark following NGS guidelines, submit the data to OPUS and select the option to share. When sharing an OPUS solution, NGS will also request a brief description and photos of the mark for quality control. Two independent OPUS solutions for each mark are highly desirable for confirming results. The list indicates howmany observations NGS has received on each bench mark (see the “obs_cnt” column). The aforementioned This is an opportunity for your society to help all constituents in your state in need of orthometric heights. Your state society could organize an effort using your chapters to occupy as many of these bench marks as possible. tracking map also shows the number of new, independent observations NGS is requesting for the marks. Please note that this tracking map will be updated as OPUS solutions are accepted by NGS, so we recommend checking it often. American Association for Geodetic Surveying It is also worth noting that marks on this list may be inaccessible, destroyed, or at sites that are unsuitable for collecting GNSS (e.g., trees, buildings, etc.). If this is the case, please locate and observe another nearby NAVD 88 benchmark, within ~10 km. Attached is a map showing the potential changes between GEOID12B and the new hybrid geoid model. While data would be helpful on or near all of the marks on the list, you may consider focusing your data collection efforts by looking for areas in this map that show large changes in your region. For further information or to dis - cuss options for collaborating with other regional partners, please consult with your NGS Regional Geodetic Advisor and/ or State Geodetic Coordinator. Questions to NGS may also be directed to ngs.GP - SonBM@noaa.gov . For additional information, Dave Zilkos - ki recently published an article on this topic for GPS World, which can be viewed at http://gpsworld.com/ ngs-2018-gps-on-bms-program-in-sup - port-of-napgd2022-part-5/. q GEODETIC continued from page 27