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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

know the processes that govern the interactions on the shorter time scales of a few days and beyond. Satellite images reveal that the development of convective clouds in the Sahel is sensitive to wet surface soil moisture patches ( Taylor and Ellis 2006 ). The mechanisms behind their formation are mesoscale gradients in land surface properties; for example, soil moisture from recent rainfall can induce circulations in the atmosphere, which could lead to subsequent rainfall ( Taylor et al. 2003

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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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Adrian M. Tompkins and Laura Feudale

. Climate , 20 , 4014 – 4032 . 10.1175/JCLI4218.1 Taylor, C. M. , Said F. , and Lebel T. , 1997 : Interactions between the land surface and mesoscale rainfall variability during HAPEX-Sahel. Mon. Wea. Rev. , 125 , 2211 – 2227 . 10.1175/1520-0493(1997)125<2211:IBTLSA>2.0.CO;2 Thomson, M. C. , Doblas-Reyes F. J. , Mason S. J. , Hagedorn R. , Connor S. J. , Phindela T. , Morse A. P. , and Palmer T. N. , 2006 : Malaria early warnings based on seasonal climate forecasts from

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Sen Chiao and Gregory S. Jenkins

forecasts were integrated until 1200 UTC 22 August 2006. The planetary boundary layer (PBL) scheme used for this study was the Yonsei University PBL scheme ( Hong and Dudhia 2003 ). The atmospheric radiation scheme accounts for longwave [i.e., the Rapid Radiative Transfer Model (RRTM); Mlawer et al. (1997) ] and shortwave ( Dudhia 1989 ) transfers and interactions with the atmosphere, clouds, and the surface. Precipitation was produced from both grid-scale condensation and convection in the 25-km

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O. Bock and M. Nuret

framework of the African Monsoon Multidisciplinary Analyses (AMMA; information online at http://www.amma-international.org ), NWP models thus play a crucial role in many scientific research areas. One of the main objectives of AMMA is that of improving our knowledge of land, ocean, and atmosphere processes and the interactions of the West African monsoon (WAM) system ( Redelsperger et al. 2006 ). The skill of NWP models in predicting rainfall over West Africa, and the tropics in general, is especially

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