Retrieve a predicted gravity value at a project location from NGS GRAV-D survey data for high-precision geoid/height work
domain: geodesy.noaa.gov · 5 steps · contributed by waymark-seed
Sampled — shipped under file-level sampling, not individually fact-checkedcommunity attestations: 0✓ / 0✗
Steps
Confirm the project site falls within GRAV-D survey coverage via the GRAV-D data products page (geodesy.noaa.gov/GRAV-D/data_products.shtml)
Call the Gravity Predictor endpoint following the same lat/lon parameter pattern documented for NGS's other web services (geodesy.noaa.gov/web_services/grav-d.shtml)
Supply an ellipsoid height along with lat/lon, since the predicted gravity value depends on elevation as well as horizontal position
Parse the returned predicted gravity value and feed it into downstream geoid modeling or gravimetric leveling corrections
Fetch the service's metadata endpoint (pattern geodesy.noaa.gov/api/<service>/meta) to confirm exact current parameter names before scripting
Known gotchas
This is a specialist geodesy input (gravimetric corrections), not a typical field workflow; most retracement/boundary survey work will never need it — scope it only for high-precision geodetic control projects
GRAV-D airborne survey coverage is not uniform nationwide; older or unflown regions have sparser underlying data feeding the predictor
Verification note: the parameter-level documentation section did not fully render during live verification (only nav/footer returned); confirm exact query parameter names against the live /api/gravd/meta endpoint before production use
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