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Fatima Karbou, Elisabeth Gérard, and Florence Rabier

regressions and empirical models ( Weng et al. 2001 ; Grody 1988 ) has been used in NWP and has facilitated the assimilation of AMSU channels over land. The effectiveness of these models depends on the input parameters about the surface, for which a global analysis does not always exist. To date, observations are more intensively used over sea than over land thanks to effective sea emissivity models ( Deblonde and English 2000 ; Guillou et al. 1998 ; Prigent and Abba 1990 ; Guissard and Sobieski 1987

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Fatima Karbou, Florence Rabier, Jean-Philippe Lafore, Jean-Luc Redelsperger, and Olivier Bock

information content, gave a valuable description of the temperature and humidity at different levels in the atmosphere. The use of these measurements in NWP has led to substantial progress being made, but more effort is needed to assimilate many more observations in a wide range of atmospheric situations (clear, cloudy) and with a variety of surface conditions (ocean, land, snow, etc.). However, many issues are still to be addressed, in particular, the assimilation of observations in the presence of

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Xuefeng Cui, Douglas J. Parker, and Andrew P. Morse

1. Introduction This paper investigates the atmospheric surface layer response to the frequency of rainfall events and the subsequent drying out of the land surface. It will show that the frequency of rainfall events is important for keeping temperatures within a critical range for the survivability of mosquitoes and thus influences the transmission of malaria. The notion of coupling between evaporation and precipitation (e.g., Mintz and Serafini 1992 ) has been developed to show that a

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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

–29 August time interval is presented using satellite-based estimates of rainfall and surface incoming solar flux, together with the latent heat flux (LE) derived from these products with land surface modeling ( Boone et al. 2009 ); see section 4 (and Table 3 ) for further details on these products. According to these estimates, the 24-h rainfall and evapotranspiration ( E ) display high and related variability from one day to the next. Links between the rainfall and subsequent LE patterns are obvious

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C. Faccani, F. Rabier, N. Fourrié, A. Agusti-Panareda, F. Karbou, P. Moll, J.-P. Lafore, M. Nuret, F. Hdidou, and O. Bock

, provide indirect information about the atmospheric temperature and humidity structure with a relatively coarse vertical resolution, compared to radiosonde profiles. Furthermore, they are more difficult to use over land than over sea and, as a consequence, are only partially used over land. Only high-peaking channels, describing the stratosphere and upper troposphere, are generally assimilated. Information about the lower troposphere is then lacking from satellite data over the African continent

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O. Bock and M. Nuret

use a 3DVAR system with 28 vertical levels from the surface up to 3 Pa and a spectral truncation of T62 (i.e., horizontal resolution of ∼210 km). Because it has coarser horizontal resolution, fewer surface stations are assimilated in regions of steep topography. There are many differences also in the parameterizations and the treatment of surface variables over land (e.g., the way soil moisture is adjusted from the observations). For what concerns the water cycle, NCEP2 is usually considered to be

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

troposphere. This is due to some known issues with AMV height assignments (e.g., Velden et al. 2005 ; Velden and Bedka 2009 ) and the resulting large discrepancy (departure) with the model values at the observation locations, which can have negative impacts on the forecasts ( von Bremen 2005 ). Because of these issues, only high-level AMVs (above 400 hPa) are assimilated in the AMMA domain over land. AMVs from visible channels are used below 400 hPa only over the ocean. Despite these restrictions

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Benjamin Sultan, Serge Janicot, and Cyrille Correia

variability of convection in other regions of the tropics. Most of these examples concern the prediction of the Madden–Julian oscillation (MJO), which is the dominant oscillatory mode in the tropics ( Madden and Julian 1972 ). Skillful predictions of the MJO have been obtained at a medium lead time (less than 10 days) using either dynamical forecasts or statistical methods. For instance, the National Centers for Environmental Prediction (NCEP) Medium-Range Forecast (MRF) model shows skillful forecasts of

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Adrian M. Tompkins and Laura Feudale

boundary layer could result from a dry land surface [shown to be potentially important in Douville and Chauvin (2000) ], and replacing the land surface scheme with a soil moisture history derived using observed precipitation has a small but nevertheless positive impact on rainfall in the Sahel, moving the rainband slightly northward in the model simulations ( A. Agusti-Panareda et al. 2009 ). The humidity and pressure gradients are also affected by the Saharan heat low; thus, representations of both

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Ryan D. Torn

respect to rawinsonde observations, short-term forecasts of AEWs were characterized by varying degrees of skill. These operational systems use different initial conditions and physics parameterizations; thus, it is difficult to separate the role of initial-condition and model errors. This paper explores how initial-condition errors affect NWP model forecasts of AEWs using forecast sensitivity analysis. Specifically, this study uses ensemble analysis and forecast data from a cycling ensemble Kalman

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