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    • GRACE NON-TIDAL ATMOSPHERE AND OCEAN GEOPOTENTIAL COEFFICIENTS JPL RELEASE 6.0 GAC

    Metadata Updated: September 19, 2025

    FOR EXPERT USE ONLY. This dataset contains estimates of geopotential field derived from the Gravity Recovery and Climate Experiment (GRACE) mission measurements and a non-tidal oceanic and atmospheric model produced by the NASA Jet Propulsion Laboratory (JPL). The data are in spherical harmonics averaged over approximately a month. The primary objective of the GRACE mission is to obtain accurate estimates of the mean and time-variable components of the gravity field variations. This objective is achieved by making continuous measurements of the change in distance between twin spacecraft, co-orbiting in about 500 km altitude, near circular, polar orbit, spaced approximately 200 km apart, using a microwave ranging system. In addition to these range change, the non-gravitional forces are measured on each satellite using a high accuracy electrostatic, room-temperature accelerometer. The satellite orientation and position (and timing) are precisely measured using twin star cameras and a GPS receiver, respectively. Spatial and temporal variations in the gravity field affect the orbits (or trajectories) of the twin spacecraft differently. These differences are manifested as changes in the distance between the spacecraft, as they orbit the Earth. This change in distance is reflected in the time-of-flight of microwave signals transmitted and received nearly simultaneously between the two spacecraft. The change in this time of fight is continuously measured by tracking the phase of the microwave carrier signals. The so called dual-one-way range change measurements can be reconstructed from these phase measurements. This range change (or its numerically derived derivatives), along with other mission and ancillary data, is subsequently analyzed to extract the parameters of an Earth gravity field model.

    Access & Use Information

    Public: This dataset is intended for public access and use. License: No license information was provided. If this work was prepared by an officer or employee of the United States government as part of that person's official duties it is considered a U.S. Government Work.

    Downloads & Resources

    Dates

    Metadata Created Date April 11, 2025
    Metadata Updated Date September 19, 2025

    Metadata Source

    Harvested from NASA Data.json

    Other Data Resources

    Additional Metadata

    Resource Type Dataset
    Metadata Created Date April 11, 2025
    Metadata Updated Date September 19, 2025
    Publisher NASA/JPL/GRACE-TELLUS-0001;NASA/JPL/PODAAC
    Maintainer
    Identifier 10.5067/GRGAC-20J06
    Data Last Modified 2025-09-11
    Category Earth Science
    Public Access Level public
    Bureau Code 026:00
    Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
    Schema Version https://project-open-data.cio.gov/v1.1/schema
    Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
    Harvest Object Id af7b18bc-d925-4202-b963-7200323d77ba
    Harvest Source Id 58f92550-7a01-4f00-b1b2-8dc953bd598f
    Harvest Source Title NASA Data.json
    Homepage URL https://podaac.jpl.nasa.gov/CitingPODAAC
    Old Spatial "CARTESIAN",{"WestBoundingCoordinate":-180.0,"SouthBoundingCoordinate":-88,"EastBoundingCoordinate":180.0,"NorthBoundingCoordinate":88}
    Program Code 026:000
    Source Datajson Identifier True
    Source Hash 90a4689766db49bd47ba2fd54e600f37ab1d6cd11a1f76fbcbc28b6b89e088b5
    Source Schema Version 1.1
    Spatial
    Temporal 2002-04-04/2002-04-04

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