Monitoring of extreme land hydrology events in central Poland using GRACE, land surface models and absolute gravity data

This study deals with the analysis of temporal gravity variations in central Poland, deduced from multiple sources and covering the period from 2002-2016. The gravity data sets used comprise GRACE monthly solutions, GLDAS land surface models and absolute gravimeter measurements from the FG-5 gravimeter located in Józefosław, Poland. All data are corrected using standard processing methods in order to include the same gravity effects. After removing the annual and semi-annual components from all data using least-squares spectral analysis and seasonal-trend decomposition, the deseasoned time series are derived and examined for signatures of extreme hydrological events. The signatures of several severe drought and flood conditions affecting Poland and central Europe are identified. A complementary correlation analysis is performed to assess the level of agreement between different data sources. A higher correlation is shown when the analysis is restricted in the 2009-2012 period that includes the 2010 extreme flood and 2011 increased precipitation events, both affecting Poland.