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| DOI | 10.5067/GRGAB-20J06 |
| Short Name | GRACE_GAB_L2_GRAV_JPL_RL06 |
| Description | 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. |
| Version | 6.0 |
| Dataset Type | OPEN |
| Measurement | SOLID EARTH > GRAVITY/GRAVITATIONAL FIELD > GRAVITY OCEANS > OCEAN PRESSURE > WATER PRESSURE |
| Processing Level | 2 |
| Coverage | Region: Global Northernmost Latitude: 88 degrees Southernmost Latitude: -88 degrees Westernmost Longitude: -180 degrees Easternmost Longitude: 180 degrees Time Span: 2002-Apr-04 to 2017-Jun-30 Granule Time Span: 2002-Apr-04 to 2017-Jun-29 |
| Resolution | Spatial Resolution: 500 km (Along) x 500 km (Across) |
| Projection | Type: Spherical Detail: N/A Ellipsoid: WGS 84 |
| Latency | hours |
| Swath Width | - km |
| Sample Frequency | - |
| Temporal Repeat (Nominal) | 1 Month |
| Temporal Repeat (Min) | - |
| Temporal Repeat (Max) | - |
| Platform/Sensor | GRACE / Platform Name: Gravity Recovery and Climate Experiment (GRACE) Orbit Period: -1 minutes Inclination Angle: 89 degrees Ascending Node: 1970-Jan-01 00:00:00 GRACE SCA SENSOR Name: Star Camera Assembly (GRACE SCA) Swath Width: - km Description: The two star cameras mounted close to the accelerometer on each satellite provide the precise attitude references for the satellites when making science measurements. GRACE / Platform Name: Gravity Recovery and Climate Experiment (GRACE) Orbit Period: -1 minutes Inclination Angle: 89 degrees Ascending Node: 1970-Jan-01 00:00:00 GRACE KBR SENSOR Name: GRACE K-Band Ranging System (GRACE KBR) Swath Width: -1 km Description: This instrument precisely measures the changes in the separation between the two GRACE satellites using phase tracking of K- and Ka-band signals sent between the two satellites GRACE / Platform Name: Gravity Recovery and Climate Experiment (GRACE) Orbit Period: -1 minutes Inclination Angle: 89 degrees Ascending Node: 1970-Jan-01 00:00:00 GRACE ACC SENSOR Name: GRACE SuperSTAR Accelerometer (GRACE ACC) Swath Width: -1 km Description: The accelerometer, located at the center of mass of each satellite, measures all non-gravitational forces acting on each satellite. These forces include air drag, solar radiation pressure, and attitude control activator operation. |
| Project | Gravity Recovery and Climate Experiment (GRACE) |
| Data Provider | Creator: GRACE Release Place: JPL PO.DAAC Release Date: 2018-Jul-05 Resource: https://podaac-tools.jpl.nasa.gov/drive/files/allData/grace/docs/ |
| Keyword(s) | gravity, GRACE, GAB, JPL, RL06 |
| Persistent ID | PODAAC-GRGAB-20J06 |
Questions related to this dataset? Contact podaac@podaac.jpl.nasa.gov
| PO.DAAC DRIVE | https://podaac-tools.jpl.nasa.gov/drive/files/allData/grace/L2/JPL/RL06 |
| Format (Compression) | ASCII (GZIP) |
| Web Service | https://podaac.jpl.nasa.gov/ws/search/granule/?datasetId=PODAAC-GRGAB-20J06 (Search Granule) |
| Announcements | |
| ReleaseNotes_jpl_RL06.pdf | https://podaac-tools.jpl.nasa.gov/drive/files/allData/grace/docs/ReleaseNotes_jpl_RL06.pdf Release Notes for GRACE L-2 products - version JPL RL-06 |
| User's Guide | |
| L2-JPL_ProcStds_v6.0.pdf | https://podaac-tools.jpl.nasa.gov/drive/files/allData/grace/docs/L2-JPL_ProcStds_v6.0.pdf JPL Level-2 Processing Standards Document For Level-2 Product Release 06 |
| L2-UserHandbook_v4.0.pdf | https://podaac-tools.jpl.nasa.gov/drive/files/allData/grace/docs/L2-UserHandbook_v4.0.pdf Level-2 Gravity Field Product User Handbook |
| ProdSpecDoc_v4.6.pdf | https://podaac-tools.jpl.nasa.gov/drive/files/allData/grace/docs/ProdSpecDoc_v4.6.pdf Product Specification Document |
| Project Materials | |
| GRACE Project | https://podaac.jpl.nasa.gov/GRACE GRACE Mission Page |
| Citation | GRACE. 2018. GRACE NON-TIDAL OCEAN GEOPOTENTIAL COEFFICIENTS JPL RELEASE 6.0 GAB. Ver. 6.0. PO.DAAC, CA, USA. Dataset accessed [YYYY-MM-DD] at https://doi.org/10.5067/GRGAB-20J06.
For more information see Data Citations and Acknowledgments.
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| Journal Reference | Bettadpur, S. 2018. Gravity Recovery and Climate Experiment Level-2 Gravity Field Product User Handbook. Center for Space Research at The University of Texas at Austin https://podaac-tools.jpl.nasa.gov/drive/files/allData/grace/docs/L2-UserHandbook_v4.0.pdf | |||||||
