Role of land-surface hydrology schemes in simulating the global incident solar radiation of Tropical Africa using the RegCM4

In the present study, two 12-years (1995-2007) simulations were conducted to examine the potential influence of two land-surface hydrology schemes (TOPMODEL; TOP and Variable Infiltration Capacity; VIC) of the community land model version 4.5 (CLM45) on the Surface Solar Irradiance (SSI) of Tropical using a regional climate model (RegCM4). With enabling the Carbon-Nitrogen (CN) module, the two simulations were designated as: CN-TOP and CN-VIC. The two simulations were evaluated with respect to the Solar Radiation Budget (SRB) reanalysis product. Evaluation process was conducted in two aspects: seasonal climatology overall Africa and over three sub-regions. The results showed that the CN-VIC outperforms the CN-TOP in all seasons while compared to the SRB reanalysis dataset particularly during the summer season. For instance, the CN-VIC underestimates the SSI over the Northern Savannah region by up to 15 W.m^-2, while the CN-TOP underestimates the SSI by 30-50 W.m^-2. Over different sub-regions, the CN-VIC performs better than the CN-TOP over Northern Savanna during the summer season and over the Congo basin during the winter season. The regional coupled RegCM4-CLM45-CN-VIC model can reasonably simulate the SSI with a reasonable bias when the four parameters of the VIC surface dataset are calibrated against in-situ observation, and therefore it can be recommended for future studies of solar energy projects in Tropical Africa.