Parsing the Earth's Gravitational Pulse Measured by GRACE Using Seasonal Signals and Monthly Estimates of Storage Changes in Hydrological Components
Abstract
NASA's GRACE satellite has been measuring spatial and temporal changes in the earth's gravitational field for more than fifteen years. Much of the effort in interpreting the GRACE data has focused on estimating multi-year storage declines resulting from, for example, regional groundwater extraction or the melting of glaciers. In contrast, few studies have examined the implications of the seasonal water storage signal detected by GRACE. As one aspect of a broader USGS Powell Center study on using GRACE data in ground-based monitoring and modeling, we are examining seasonal GRACE signals and correlating them to changes in water storage signals that have been quantified for the conterminous United States (CONUS). Independent estimates have been made of seasonal changes in snowpack, soil water content, surface water, and groundwater storage as well as man-made impacts such as irrigation pumping from regional aquifers. For example, summer pumping of thirty-five million cubic meters per day from the Mississippi Alluvial Plain aquifer creates a gravity signal amplitude equivalent to 7 mm of water seasonally, whereas the Great Lakes' water levels create a seasonal signal of 25 mm. Surface water lake and reservoir signals tend to peak in midsummer, providing an substantial offset to the groundwater storage component that usually peaks in late winter, creating a combined signal that GRACE observes peaking in mid-spring. The decomposition of the GRACE seasonal signal into its components is providing important constraints on aquifer storage properties as part of our ongoing work to calibrate a national-scale groundwater model of the CONUS.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.H43M2237S
- Keywords:
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- 1836 Hydrological cycles and budgets;
- HYDROLOGY;
- 1847 Modeling;
- HYDROLOGY;
- 1855 Remote sensing;
- HYDROLOGY;
- 1873 Uncertainty assessment;
- HYDROLOGY