Present status of soil moisture estimation over the African continent

Abstract

Soil moisture is the key parameter that governs the partitioning of the mass and energy fluxes between land and atmosphere through its influence on surface evaporation, runoff, albedo and emissivity. Therefore, accurate quantification of soil moisture is critical in the study of the soil-plant-atmosphere continuum as well as in hydrology and climate change studies. However, soil moisture remains a challenging hydrometeorological variable to monitor and interpret over high temporal and spatial resolution. The cost of setting up, operating and maintaining dense soil moisture networks across different agro-climatic zones of the African regions is currently financially unattainable due to high competition for resources. Consequently, soil moisture is often estimated indirectly, using both remote sensing and hydrological models, which provide periodic updates and valuable estimates at lower cost over African continent thus far. In recent years, huge efforts have been undertaken to install in situ soil moisture monitoring networks to support the satellite retrievals, satellite product improvement and modelling in Africa. However, the lack of large and representative in situ soil moisture monitoring networks across different agro-climatic zones of the African regions still hinders evaluation and verification of the most promising remote sensing products and hydrological models to estimate soil moisture. Consequently, the need for accurate and continuous real-time in situ soil moisture measurements covering a wide range of agro-climatic zones of the African continent is indisputable. Keywords: Calibration, In situ measurements, Modelling, Remote sensing, Validation