Water Cycle and Climate Signals in Africa Observed by Satellite Gravimetry

The availability of hydrologic data is an important step for hydrological modeling and water resource management in the world. Unfortunately, the in situ observations with the right characteristics are very sparse globally, particularly in Africa. Understanding the climate variability of Africa and its prominent role as the heat engine of the global climate system is one of the key goals in climate research. Also, studies show that the time varying of terrestrial water storage contributes significantly to regional climate. In this paper, we have analyzed terrestrial water storage variations from GRACE satellite mission and from GLDAS model over the whole Africa for the period of August 2002 till April 2012. Amplitudes of water storage and rainfall data over some large river basins in Africa have been studied at seasonal and interannual scales. Comparison with the GLDAS model outputs is performed and discussed. Terrestrial Water Storage (TWS) estimates from GRACE and GLDAS show comparable patterns, however GRACE is better to detect interannual variation in water storage. Comparing TWS with rainfall data shows a phase lag of around one month between the maximum of the rainfall over a region and the maximum of TWS over the same region.