The Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission, a joint partnership between NASA and the German Research Centre for Geosciences (GFZ), launched on 22 May 2018. It uses twin satellites to accurately map month-to-month variations in the Earth's gravity field and surface mass changes. It will continue the legacy data record of the first Gravity Recovery and Climate Experiment (GRACE) mission (2002-2017).
Conceptually very similar to the original GRACE mission, GRACE-FO consists of two identical satellites flying in formation around Earth at an initial altitude of approximately 490 kilometers and a nominal separation distance of 220+/-50 kilometers. Instruments on board the satellites precisely measure changes in the distance between them due to orbital perturbations caused by geographical and temporal variations in Earth's gravity field.
GRACE-FO will expand GRACE's legacy of scientific achievements. These include tracking mass changes in Earth's polar ice sheets and mountain glaciers (which impacts global sea level); estimating total water storage on land (from groundwater changes in deep aquifers to changes in soil moisture and surface water); inferring changes in deep ocean currents, a driving force in climate; and even measuring changes within the solid Earth itself, such as postglacial rebound and the impact of major earthquakes.
The JPL GRACE and GRACE-FO Level-3 Mascon Ocean, Ice, and Hydrology Equivalent Water Height Release-06 (RL06) version 02 datasets are derived from solving for monthly gravity field variations in terms of geolocated spherical cap mass concentration functions, rather than global spherical harmonic coefficients. Additionally, realistic geophysical information is introduced during the solution inversion to intrinsically remove correlated error. Thus, these Mascon grids do not need to be destriped or smoothed, like traditional spherical harmonic gravity solutions. The complete Mascon solution consists of 4,551 relatively independent estimates of surface mass change that have been derived using an equal-area 3-degree grid of individual mascons. The final solutions are then mapped into 0.5-degree regular lat-lon grid.
GRACE-FO mission datasets are archived and distributed by the PO.DAAC. The JPL GRACE and GRACE-FO Level-3 Mascon Rl06 v02 datasets are described and discoverable via the PO.DAAC dataset information pages (https://podaac.jpl.nasa.gov/dataset/TELLUS_GRAC-GRFO_MASCON_CRI_GRID_RL06_V2 and https://podaac.jpl.nasa.gov/dataset/TELLUS_GRAC-GRFO_MASCON_GRID_RL06_V2). The dataset information pages also provide access to the technical documentation, JPL GRACE/GRACE-FO MASCON Release Notes, GRACE Mason references, and guidance on how to cite the data.
Animation of the JPL GRACE and GRACE-FO Mascon L3 Monthly Global Mass Anomaly RL06Mv2 CRI from 2002 to 2019.