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Adrian M. Tompkins and Laura Feudale

-of-the-atmosphere (TOA) infrared flux is often used as a proxy for convective activity. The difference map ( Fig. 9 ) shows a large region over West Africa where the biases are negative (TOA IR flux is assigned positive downward), signifying too high outgoing longwave radiation. This agrees with the previous precipitation biases, indicating a lack of deep convection in the Sahel in this model cycle, although it should be recalled that TOA infrared flux information is used in the GPCP rainfall retrieval algorithms

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

structure of the AEJ. The presence of cold cloud tops is assessed using Meteosat-8 infrared images, which are also not assimilated. The AMV data were gridded at 2° resolution from 750 to 500 hPa to cover the vertical layer of the AEJ. The mean zonal winds from the AMVs and from the two analysis experiments during August 2006 for the same layer are plotted in Fig. 10 . In general, there are large differences in the structure of the AEJ between the AMVs and the experiments. In the jet exit (around 15°W

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

observations. Indeed, the fit of other observations against FGs or analyses is not altered when surface-sensitive temperature or humidity observations are assimilated over land. The fit of the SSM/I and High Resolution Infrared Radiation Sounder (HIRS) observations compared to that the FG is even better than in CTL for EXP4–EXP6, especially over the tropics. These observations are very informative about the humidity in the atmosphere. Figure 5 shows the model fit in terms of bias and standard deviation

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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

evapotranspiration, together with atmospheric water transport, is required for an accurate estimation of water budgets (e.g.; Drusch and Viterbo 2007 ). Such estimates, therefore, require the modeling of atmospheric processes and land–ocean–atmosphere interactions over a range of temporal and spatial scales. For example, the diurnal cycle of solar radiation over West Africa is responsible for very significant diurnal modulations of atmospheric convection, whether dry, moist, shallow, or deep precipitating

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Peter Knippertz and Andreas H. Fink

includes microwave precipitation estimates based on Special Sensor Microwave Imager (SSM/I) data from the polar-orbiting Defense Meteorological Satellite Program (DMSP) satellites and infrared (IR) precipitation estimates from geostationary and polar-orbiting satellites. Additional low-earth orbit estimates include the Atmospheric Infrared Sounder (AIRS) data from the National Aeronautics and Space Administration (NASA) Aqua satellite, and Television Infrared Observation Satellite Program (TIROS

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Sen Chiao and Gregory S. Jenkins

design are described in section 3 . The results of our model simulations are discussed and evaluated against observations in section 4 , followed by discussion and conclusions in section 5 . 2. MCS progression and TD formation TD 4 developed near 11.6°N and 21.7°W at 1800 UTC 21 August 2006 ( Jenkins et al. 2008 ), from a series of MCSs that propagated westward across western Africa. Figures 1a–d depict the evolution of the MCS using infrared (IR) cloud-top temperatures from 1200 UTC 19 August

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Benjamin Sultan, Serge Janicot, and Cyrille Correia

for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA-40). In addition, we use satellite outgoing longwave radiation (OLR) data to estimate deep convection. The approach is twofold. We first document the intraseasonal variability in the IRD rainfall dataset, providing the most reliable measurement of the ground-based truth. We apply the SSA to a rainfall index in West Africa computed from the IRD rainfall dataset to statistically extract the main leading modes of intraseasonal variability

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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

a horizontal resolution on the order of 50 km over western Africa. Conventional observations such as radiosonde or surface data are operationally assimilated into ARPEGE 4DVAR. Radiosonde temperature data are corrected with functions depending on the sonde type and the solar elevation, similarly to the bias correction previously used at ECMWF ( Bouttier et al. 1999 ). Clear-sky radiances from satellite instruments [e.g., the High Resolution Infrared Radiation Sounder (HIRS), the Advanced

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