Climate impact of deforestation over South Sudan in a regional climate model

摘要

This study examines the sensitivity of climate to changes in vegetation cover and land use in South Sudan. The focus lies on the effect of deforestation on precipitation and surface temperature especially during the rainy season. Sensitivity experiments are performed with the third version of the Abdus Salam International Centre for Theoretical Physics Regional Climate Model (RegCM3) where the present forest and vegetation cover south of 10°N in Sudan are replaced by either grass or, as an extreme case, desert. The model experiments were conducted for a time period of almost 21 years, from January 1989 to August 2009, and were preceded by a control experiment to ascertain the fidelity of the model simulations. The experiments indicate that the vegetation changes affect precipitation and surface temperature in both Southern and Central Sudan significantly although the land cover changes were imposed only in the south. The precipitation during the rainy season (June through September) was reduced in the perturbed region by about 0.1-2.1 mm d~(-1) for the desert scenario and by 0.1-0.9 mm d-1 for the grass scenario. The surface temperature increases by about 1.2 and 2.4 °C in the grass and desert scenario, respectively. The precipitation reduction is thus not only local but also extends to Central Sudan and neighbouring regions. The study demonstrates significant dependency for Southern and Central Sudan precipitation on the land use in Southern Sudan and indicates that the deforestation has both local and non-local regional climatic effects.