sensors Article Terrestrial Water Storage in African Hydrological Regimes Derived from GRACE Mission Data: Intercomparison of Spherical Harmonics, Mass Concentration, and Scalar Slepian Methods Ashraf Rateb 1,2,*, Chung-Yen Kuo 1, Moslem Imani 1, Kuo-Hsin Tseng 3, Wen-Hau Lan 1, Kuo-En Ching...