The study of large-scale variability in total water storage within the context of modern satellite gravity missions

The analysis of Earth’s gravity field changes is the one of essential task of physical geodesy. So the knowledge about selected characteristics of gravity field is the basic element of the Earth shape determining process and help to find information about mass redistribution in the Earth system. Since 2002, the gravity field changes have been successfully observed by the Gravity Recovery and Climate Experiment (GRACE) satellite gravity mission and its continued GRACE-FO (GRACE Follow-On) mission. The results obtained from GRACE/GRACE-FO observations are presented, among other, in form of mascons and they are provid-ed by three processing centers: (1) Center for Space Research (CSR; Austin, United States), (2) Jet Propulsion Laboratory (JPL; Pasadena, United States), and (3) Goddard Space Flight Center (GSFC; Maryland, United States). In the following study, we used data provided by GSFC in form of the global distribution of Total Water Storage (TWS), which are expressed in terms of Equivalent Water Height (EWH). In our study, we focused on identifying areas with significant changes in TWS. We analysed TWS fluctuations in seasonal short-term changes, i.e., amplitude of annual oscillation (the most pronounced oscillation in the land hydro-sphere) and longterm changes, i.e., trend (a key parameter for climate studies) determined using the Least Squares Method. As a result, we selected 15 areas characterised by extreme TWS changes, i.e., 11 areas for annual amplitude and 4 areas for trend parameter. We obtained seasonal changes greater than 140 mm in areas within the equator (mainly Amazon, Niger, Ganges, Brahmaputra river basin regions) and areas covered by huge ice masses (Alaska, Greenland). The greatest rate of change in water storage at ±70 is observed around West Antarctica, Patagonia or the Caspian Sea. The results also emphasize the significant human impact in continental water masses (e.g. Mexico, Indus and Ganges river basins). Keywords: GRACE, TWS, land hydrology, gravity missions