Cascading Spatial Scales in the Hydrological Cycle Over Africa

Characterizing hydrological variability is critical for water resource management in Africa. However, whether a spatial cascading link exists within the hydrological cycle remains poorly understood. Using satellite-based precipitation, soil moisture (SM), and vegetation products during 2016–2023, we quantify and compare their spatial scales, defined as the distance over which a variable maintains similar temporal variations, across Africa. Results show spatial scales increase sequentially from precipitation to SM to vegetation. Spatial scales diverge from precipitation to the land surface, with precipitation scales having a weak positive correlation with SM scales and moderately negatively correlated with vegetation scales. Soil moisture and vegetation scales remain positively coupled. Regional analyses reveal stronger scale coupling in semi-arid regions. Seasonally, precipitation–soil moisture scale correlation intensifies from onset to peak of the rainy season across all unimodal regimes, whereas SM-vegetation scale coupling weakens slightly. Our study provides critical insights into land-atmosphere interactions across Africa.