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Abstract:
The National Geodetic Survey (NGS) has been collecting airborne gravity data as part of its Gravity for the Redefinition of the American Vertical Datum (GRAV-D) project since 2008. The end of the first phase of the data collection is approaching (10km line spacing over the US and all of its territories - currently over 97% complete), and all of the data collected to date have been reprocessed. This allows NGS to incorporate a variety of improvements over the initial data set: analysis of multiple East/West line repeats (providing instrument calibration information), a reanalysis of airport absolute gravity ties, consistent use of ITRF2020 positioning throughout the data set, improved off-level corrections, filtering of the gravity disturbance, as well as a generally more consistent and automated (where possible) reduction of raw gravity. The latest version of these efforts also includes all lines flown in partially completed survey areas (or "blocks").We will provide statistics quantifying the improved results - comparisons with gravitational models, crossover line analysis, repeat line analysis, and adjacent line correlations - along with conclusions on their implications. We will also describe the formats and availability of the revised data products.
