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Journal Article: BibTeX citation key:  Praxian2016
Praxian, A., Sein, D., Brücher, T., Panitz, H.-J., Warscher, M., Breil, M., Engel, T., Engel, T., Tödter, J., Krause, A., Cabos Navaez, W. D., Fink, A. H., Kunstmann, H., Jakob, D. & Paeth, H. (2016) Bias reduction in decadal predictions of West African monsoon rainfall using regional climate models. IN Journal of Geophysical Research - Atmospheres, 121.
Added by: Andreas Fink 2016-03-01 12:45:31
Categories: Weather to Climatic modelling and forecasting
Keywords: Downscaling, Dynamics, Land use, Modelling, Rainfall, Sahel
Creators: Brücher, Breil, Cabos Navaez, Engel, Fink, Jakob, Krause, Kunstmann, Paeth, Panitz, Praxian, Sein, Tödter, Warscher
Collection: Journal of Geophysical Research - Atmospheres

Peer reviewed
Number of views:  244
Popularity index:  18.01%

The West African monsoon rainfall is essential for regional food production, and decadal
predictions are necessary for policy makers and farmers. However, predictions with global climate models
reveal precipitation biases. This study addresses the hypotheses that global prediction biases can be reduced
by dynamical downscaling with a multimodel ensemble of three regional climate models (RCMs), a RCM
coupled to a global ocean model and a RCM applying more realistic soil initialization and boundary
conditions, i.e., aerosols, sea surface temperatures (SSTs), vegetation, and land cover. Numerous RCM
predictions have been performed with REMO, COSMO-CLM (CCLM), and Weather Research and Forecasting
(WRF) in various versions and for different decades. Global predictions reveal typical positive and negative
biases over the Guinea Coast and the Sahel, respectively, related to a southward shifted Intertropical
Convergence Zone (ITCZ) and a positive tropical Atlantic SST bias. These rainfall biases are reduced by some
regional predictions in the Sahel but aggravated by all RCMs over the Guinea Coast, resulting fromthe inherited
SST bias, increased westerlies and evaporation over the tropical Atlantic and shifted African easterly waves. The
coupled regional predictions simulate high-resolution atmosphere-ocean interactions strongly improving the
SST bias, the ITCZ shift and the Guinea Coast and Central Sahel precipitation biases. Some added values in
rainfall bias are found for more realistic SST and land cover boundary conditions over the Guinea Coast and
improved vegetation in the Central Sahel. Thus, the ability of RCMs and improved boundary conditions to
reduce rainfall biases for climate impact research depends on the considered West African region.
Added by: Andreas Fink