NASA’s Applied Sciences Program, along with the GRACE missions project teams, are implementing a strategy that promotes applications research and engages a broad community of users in the uses of GRACE data. This activity is in response to recommendations of the National Research Council Decadal Survey report (Earth Science and Applications from Space: National Imperatives for the Next Decade and Beyond, Space Studies Board, National Academies Press, 2007). The goals of the GRACE applications program include:
- Promote the use of GRACE products to a community of end-users and decision makers that understand GRACE and related mission capabilities and are interested in using the missions’ data products in their application
- Facilitate feedback between GRACE user communities and the GRACE project
- Provide information on collaborations with different types of users and communities including those of Earth and ocean research, ice and drought studies, agricultural impacts, operational applications, and others
- Design communication strategies to target and support requirements of the user community.
GRACE Applications Areas
Groundwater is a useful indicator of climate variability and human impacts on the environment. Combining GRACE data with hydrologic modeling enables scientists and water managers to observe the dynamic changes in groundwater over large regions or where well data is sparse. GRACE-FO will continue to provide global measurements of the hydrological cycle, as the current GRACE mission does. These measurements provide information on seasonal and inter-annual river basin water storage changes, human influences on regional water storage changes, large-scale evapotranspiration, land-ocean mass exchange, and continental aquifer changes. GRACE data is currently being used to generate weekly drought indicators at the National Drought Mitigation Center.
Ice sheets and Glaciers
GRACE data is used extensively to determine mass changes of the World’s land ice (ice sheets, icefields, ice caps and mountain glaciers). Land ice continually receives mass as precipitation and losses mass through meltwater runoff and calving of solid ice into the ocean. If losses are greater than gains, the land ice loses mass causing sea level to rise. Over the last decade or so losses from land ice have been implicated in causing two thirds of the observed rise in sea level (Gardner et al., 2013 and Shepherd et al., 2012). Researchers seek to further scientific understanding of ice-sheet dynamics and land-ice response to changes in atmospheric conditions and how these processes influence rates of sea-revel change. GRACE data also provides information about seasonal and sub-seasonal variations in water transport between the continental land masses and oceans – of which the cryosphere is an important component that is generally not well represented in global hydrology models or global climate reanalysis.
An important objective of GRACE science research is to better capture gravity changes that result from changes in Earth’s mantle and lithosphere during earthquakes. Another significant application of the data is in measuring changes on land and in ocean basins due to glacial isostatic adjustment (GIA); the changes observed as regions previously covered by thick ice sheets rebound after the ice melts away. The ‘signature’ of GIA must be removed from trends in GRACE gravity data so that the data can more clearly tell the story of long-term changes in water storage.
The current and future GRACE missions will provide important information about the amount of sea level rise caused by melting ice and changes in rainfall that add water to the oceans. The GRACE missions will help distinguish these from changes caused by thermal expansion of the water, which happens as heat is added to the oceans. GRACE also reveals changes in deep ocean currents, which transport water and energy around the globe, by measuring changes in the pressure at the bottom of the ocean.
GRACE Applications Presentations
Bolten, J., et al, Looking to the Future: Forming a Comprehensive GRACE FO Applications Strategy, Presented at the 2012 GRACE Science Team Meeting, 17-19 September 2012, Potsdam, Germany. See abstract.
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