The primary science objective of the GRACE and GRACE-FO missions is to measure the Earth’s gravity field and it’s time variability with unprecedented accuracy. The increase in accuracy has been achieved by utilizing two satellites following each other on the same orbital track. To consider precise attitude and non-gravitational forces both satellites are equipped with star cameras and accelerometers. The position and velocity of the satellites is measured using onboard GPS antennae and (for validation purposes) SLR retro-reflectors. Additionally, the twin satellites are interconnected by a K-band microwave link to measure the exact separation distance and its rate of change to an accuracy of better than 0.1 µm/s. These measurements are directly coupled to the seasonal and sub-seasonal variations in the continental hydrological cycle, to ice mass loss in the large glacier systems in Greenland or Antarctica, to long wavelength ocean circulation processes or to the transport of ocean heat to Earth’s poles. Additionally, GRACE provides the time variability of the Earth’ overall external shape, the geoid. Consequently, since its launch in March 2002 this fundamental dataset has enabled dramatic improvements of seasonal and inter-annual climate change estimates.

The secondary science objective of the GRACE and GRACE-FO missions is to obtain about 150 very precise globally distributed vertical temperature and humidity profiles of the atmosphere per day using the GPS radio occultation technique.

Data is public, although an ISDC account is mandatory

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Based on the time-variable (monthly or 10-day) solutions CNES/GRGS RL04, a mean Earth gravity field model complete to degree and order 300 has been computed: EIGEN-GRGS.RL04.MEAN-FIELD.linear_mean_pole.zero_slope_extrapolation. It contains time-variable coefficients up to degree and order 90. For the higher degree part, it is based on a combined GRACE+GOCE static model: EIGEN-6C. This model has been used for Precise Orbit Determination of the altimetry satellites following the GDR-E standards

ISO 19115:2003/19139

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