A satellite-based terrestrial water storage indicator to assess the severity of a heatwave

Abstract

The emergence and development of improved tools for monitoring the occurrence, timing and duration of droughts and heatwaves are very important for water security purposes, with further implications for food security, water quality and hydropower production, among others. Unlike conventional studies that use climate and ecosystem data to assess the impact of droughts and heatwaves on land surface processes occurring at the terrestrial surface (precipitation, temperature and vegetation indexes) or in the shallow layers of the subsurface (soil water content), recent studies have characterized the severity of droughts over large regions (>100 000 km2) based on satellite observations of terrestrial water storage variations (Houbourg et al. 2012, Thomas et al. 2014). Such indicators can be used as a proxy to estimate the duration and magnitude of water deficit events. This work proposes a new methodology aimed at describing the variability of water storage deficits over space and time in three regions that suffered prominent dry spells over the last decade: Eastern Russia, the Middle East and the Western Sahel (Fig. 1). To accomplish this objective, we investigate the impact of the 2010 Northern Hemisphere summer heatwave on cumulative terrestrial water storage anomalies detected by the Gravity Recovery and Climate Experiment (GRACE) followed by a space–time aggregation. The concept of water storage deficit as defined by Thomas et al. (2014) is estimated and a deficit–duration–area curve is built for each region.