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Adrian M. Tompkins and Laura Feudale

between 2000 and 2007 show similar features (not shown). The higher-frequency variability is directly associated with the passage of African easterly waves (AEWs) ( Diedhiou et al. 1999 ; Sultan et al. 2003 ), while the 15-day modulation is distinct from AEW activity, which Mounier et al. (2008) recently claimed is linked to a feedback between convectively generated cloud, surface short radiative fluxes, and the surface pressure gradients. The analysis in Fig. 6 discards variability exceeding 32

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Françoise Guichard, Nicole Asencio, Christophe Peugeot, Olivier Bock, Jean-Luc Redelsperger, Xuefeng Cui, Matthew Garvert, Benjamin Lamptey, Emiliano Orlandi, Julia Sander, Federico Fierli, Miguel Angel Gaertner, Sarah C. Jones, Jean-Philippe Lafore, Andrew Morse, Mathieu Nuret, Aaron Boone, Gianpaolo Balsamo, Patricia de Rosnay, Bertrand Decharme, Philip P. Harris, and J.-C. Bergès

of energy partitioning between the surface sensible and latent heat fluxes, the surface net radiative flux is much larger in MesoNH than in ISBA ( Fig. 13 ). The daily mean differences can locally reach more than 200 W m −2 , and are approximately 70 W m −2 on average over the wide area 5°–20°N, 10°W–20°E. The spatial structures of the differences in Rnet and in surface incoming solar radiation (SW in ) closely match each other ( Fig. 14 ). The difference in SW in ( Fig. 14a ) reaches about 50

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Anna Agustí-Panareda, Anton Beljaars, Carla Cardinali, Iliana Genkova, and Chris Thorncroft

that the ECMWF model has problems with the cloud and precipitation over West Africa, with the ITCZ being shifted to the south and an overall lack of precipitation over the Sahel ( Agustí-Panareda and Beljaars 2008 ; Agustí-Panareda et al. 2009c ). Agustí-Panareda et al. (2009b) and Meynadier et al. (2010, manuscript submitted to J. Geophys. Res. ) have shown that the cloud and precipitation bias is linked to an overestimation of the moisture flux divergence associated with an

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O. Bock and M. Nuret

Petite Echelle–Grande Echelle (ARPEGE) model of Météo-France have a tendency to migrate the ITCZ to the north (but not enough compared to the observations) during the first few forecast days ( Tompkins et al. 2005 ; Nuret et al. 2007 ; Agusti-Panareda and Beljaars 2008 ). Errors in the analyses are partly due to systematic errors in observations [e.g., radiosonde biases; Bock et al. (2007) ] or to deficiencies in the assimilation systems [e.g., radiative transfer calculations for satellite

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