Metadata Updated: November 12, 2020

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 model produced by the 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.

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Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020

Metadata Source

Harvested from NASA Data.json

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Additional Metadata

Resource Type Dataset
Metadata Created Date November 12, 2020
Metadata Updated Date November 12, 2020
Unique Identifier Unknown
Identifier C1674784947-PODAAC
Data First Published 2018-06-11
Language en-US
Data Last Modified 2018-06-11
Category GRACE, geospatial
Public Access Level public
Bureau Code 026:00
Metadata Context
Metadata Catalog ID
Schema Version
Catalog Describedby
Citation GRACE. 2018-07-05. GRACE Non-Tidal Ocean Geopotential Coefficients JPL (GAB). Version 6.0. GRACE_GAB_L2_GRAV_JPL_RL06. JPL PO.DAAC. Archived by National Aeronautics and Space Administration, U.S. Government, JPL. GRACE, JPL, 2018-07-05, GRACE NON-TIDAL OCEAN GEOPOTENTIAL COEFFICIENTS JPL RELEASE 6.0 GAB,
Creator GRACE
Graphic Preview Description Thumbnail
Graphic Preview File
Homepage URL
Metadata Type geospatial
Program Code 026:001
Release Place JPL PO.DAAC
Series Name GRACE Non-Tidal Ocean Geopotential Coefficients JPL (GAB)
Source Datajson Identifier True
Source Hash 3c13e39466c8b83cd2ec17370839266a067f6c0b
Source Schema Version 1.1
Spatial -180.0 -88.0 180.0 88.0
Temporal 2002-04-04T00:00:00Z/2017-06-30T00:00:00Z

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