PODAAC-GRGSM-20J15

Metadata Updated: March 23, 2019

FOR EXPERT USE ONLY. This dataset contains estimates of Earths static field geototential derived from the Gravity Recovery and Climate Experiment (GRACE) mission measurements, produced by the Jet Propulsion Laboratory (JPL). The major difference between this dataset, 5.1, and 5.0 is that the Earth reference system has been changed to IERS2010 standards and S1/S2 air tide model. 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 Earths 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 Earths 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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Dates

Metadata Created Date August 1, 2018
Metadata Updated Date March 23, 2019

Metadata Source

Harvested from NASA Data.json

Additional Metadata

Resource Type Dataset
Metadata Created Date August 1, 2018
Metadata Updated Date March 23, 2019
Publisher PO.DAAC
Unique Identifier C1293263325-PODAAC
Maintainer
Jessica Hausman
Maintainer Email
Public Access Level public
Bureau Code 026:00
Metadata Context https://project-open-data.cio.gov/v1.1/schema/catalog.jsonld
Metadata Catalog ID https://data.nasa.gov/data.json
Schema Version https://project-open-data.cio.gov/v1.1/schema
Catalog Describedby https://project-open-data.cio.gov/v1.1/schema/catalog.json
Citation Archived by National Aeronautics and Space Administration, U.S. Government, PO.DAAC.
Datagov Dedupe Retained 20190322235447
Harvest Object Id b2abe2db-8dee-4e78-9a9f-8a1b802ab8d5
Harvest Source Id 39e4ad2a-47ca-4507-8258-852babd0fd99
Harvest Source Title NASA Data.json
Data First Published 2014-10-14
Homepage URL https://cmr.earthdata.nasa.gov:443/search/concepts/C1293263325-PODAAC.html
Language en-US
Metadata Type geospatial
Data Last Modified 2014-10-14
Program Code 026:001
Source Datajson Identifier True
Source Hash 08244298eaeb7ebe258a10438bf82f898453844a
Source Schema Version 1.1
Spatial -180.0 -88.0 180.0 88.0
Temporal 2002-04-01T00:00:00Z/2019-02-25T00:00:00Z
Category geospatial

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