Regional Land Surface Hydrology Impacts from Fire-Induced Surface Albedo Darkening in Northern Sub-Saharan Africa

Abstract:

Land surface hydrology models serve as an effective approach to simulate hydrological processes, especially in areas which lack in situ observational datasets. A key component to constraining the water, energy, and carbon dynamics within these models is land surface albedo because it links these cycles by driving evapotranspiration and also helps characterize soil infiltration behavior. However, most hydrological models estimate the land surface albedo based on generalized climatologic information, which can introduce uncertainty into the surface energy balance processes and water storage availability in the root-zone if done improperly. In particular, changes in surface albedo can have significant effects where dynamic and spatially heterogeneous land surface changes occur due to abrupt land cover changes, such as wildfire. Sub-Saharan Africa is one of the most fire-prone regions of the world. Thus, the current study employs the new parameterization approach based on estimated change of surface albedo due to fires over different land cover types using long term MODIS time series in the catchment-based land surface model to investigate the potential for improving soil moisture and evapotranspiration simulations in fire-prone Northern Sub-Saharan Africa. We also compare the estimated soil moisture based on new and pre-existing baseline parameterization scheme to remotely-sensed observations obtained from satellite-based soil moisture observations from the Advanced Microwave Scanning Radiometer (AMSR-E), the Soil Moisture Ocean Salinity (SMOS), and the recently launched satellite, Soil Moisture Active Passive (SMAP) instruments.