A sensitivity study on the role of the swamps of southern Sudan in the summer climate of North Africa using a regional climate model

• Published in: Theoretical and applied climatology Vol. 113; no. 1-2; pp. 63 - 81
• Main Authors: Zaroug, Modathir A. H., Sylla, M. B., Giorgi, F., Eltahir, Elfatih A. B., Aggarwal, Pradeep K.
• Format: Journal Article
• Language: English
• Published: Vienna Springer Vienna 01.07.2013; Springer; Springer Nature B.V
• Subjects: Analysis; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Atmospheric Sciences; Climate models; Climate science; Climatology; Climatology. Bioclimatology. Climate change; Earth and Environmental Science; Earth Sciences; Earth, ocean, space; Exact sciences and technology; External geophysics; Meteorology; Original Paper; Rain and rainfall; Rainforests; Sensitivity analysis; Summer; Waste Water Technology; Water Management; Water Pollution Control; Wetlands; North Africa; East Africa; Africa; Sudan; Ethiopia; Africa, West, Sahel Region; African Easterly Wave; Outgoing Longwave Radiation; Sudan; Total Cloud Cover; Regional Climate Model; Bioclimatology; Air biosphere interaction; swamps; sensitivity analysis; Regional scope; Summer; Effect on climate; Climate models; digital simulation; Vegetation effect
• ISSN: 0177-798X; 1434-4483
• DOI: 10.1007/s00704-012-0751-6

We used the regional climate model RegCM3 to investigate the role of the swamps of southern Sudan in affecting the climate of the surrounding region. Towards this end, we first assessed the performance of a high resolution version of the model over northern Africa. RegCM3 shows a good skill in simulating the climatology of rainfall and temperature patterns as well as the related circulation features during the summer season, outperforming previous coarser resolution applications of the model over this region. Sensitivity experiments reveal that, relative to bare soil conditions, the swamps act to locally modify the surface energy budget primarily through an increase of surface latent heat flux. Existence of the swamps leads to lower ground temperature (up to 2 °C), a larger north–south temperature gradient, and increased local rainfall (up to 40 %). Of particular importance is the impact on rainfall in the surrounding regions. The swamps have almost no impact on the rainfall over the source region of the Nile in Ethiopia or in the Sahel region; however, they favor wetter conditions over central Sudan (up to 15 %) in comparison to the bare desert soil conditions.