On the effects of wildfires on precipitation in Southern Africa

This study investigates the impact of wildfire on the climate of Southern Africa. Moderate resolution imaging spectroradiometer derived burned area fraction data was implemented in a set of simulations to assess primarily the role of wildfire-induced surface changes on monthly precipitation. Two post-fire scenarios are examined namely non-recovering and recovering vegetation scenarios. In the former, burned vegetation fraction remains burned until the end of the simulations, whereas in the latter it is allowed to regrow following a recovery period. Control simulations revealed that the model can dependably capture the monthly precipitation and surface temperature averages in Southern Africa thus providing a reasonable basis against which to assess the impacts of wildfire. In general, both wildfire scenarios have a negative impact on springtime precipitation. September and October were the only months with statistically significant precipitation changes. During these months, precipitation in the region decreases by approximately 13 and 9% in the non-recovering vegetation scenario, and by about 10 and 6% in the recovering vegetation wildfire scenario, respectively. The primary cause of precipitation deficit is the decrease in evapotranspiration resulting from a reduction in surface net radiation. Areas impacted by the precipitation reduction includes the Luanda, Kinshasa, and Brazzaville metropolitan areas, The Angolan Highlands, which are the source of the Okavango Rive, and the Okavango Delta region. This study suggests that a probable intensification in wildfire frequency and extent resulting from projected population increase and global warming in Southern Africa could potentially exacerbate the impacts of wildfires in the region's seasonal precipitation.