![]() ![]() ![]() ![]() Five independent variables (governance, gross domestic product (GDP) per capita, percentage of urban population, official development assistance for water and sanitation services (ODA-WSS) and female primary school completion rate) were used to explore the determinants of water security. The water security index (WSI) was developed using three biophysical (water availability, climate risk and ecosystem vitality) and two socioeconomic (water accessibility and integrated water resources management) variables. The objectives of this study are two fold: first, to develop a composite water security metric to assess water security at a national scale, and second, to explore the determinants of water security at the same scale in three developing regions – Africa, Asia-Pacific and Latin America and the Caribbean (LAC). Overall, satellite-derived rainfall products have notable errors, while GSMaP products produce comparable or better results at multiple timescales relative to CHIRPS and TAMSAT. There is an increase of 0.6–1.3 mm in satellite rainfall RMSE for a 1 km increase in elevation revealing the influence of elevation on rainfall estimation by satellite models. Considerable biases in seasonal rainfall are observed in all sub-regions for every satellite product. The highest mean monthly biases are produced by CHIRPS in East Africa (29 % 26.3 mm wet bias), TAMSAT in Southern Africa (13 % 10.4 mm dry bias) and GSMaP in West Africa (23 % 19.6 mm wet bias). Generally, for every two rainfall events predicted by CHIRPS and TAMSAT, the GSMaP products predict three or more events. We find higher daily rainfall event detection scores in the GSMaP products than in CHIRPS or TAMSAT. For daily mean rainfall over Africa, CHIRPS has the highest bias at 15.5 % (0.5 mm) whereas GSMaP_wGauge has the lowest bias at 0.02 mm (0.7 %). Validations are stratified to evaluate performance across the continent and in East Africa, Southern Africa, and West Africa at daily, pentadal, and monthly timescales. In this study, we use six years of rain gauge data from 596 stations operated by the Trans-African Hydro-Meteorological Observatory (TAHMO) to validate three gauge-calibrated satellite rainfall products – CHIRPS, TAMSAT and GSMaP_wGauge – and one satellite-only rainfall product – GSMaP. Increasingly, satellite-derived rainfall data is used for climate research and action in Africa. ![]()
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