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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

observations and their model equivalents from short-range forecasts [see Agusti-Panareda et al. (2009) for details]. Only humidity data of radiosondes located between the equator and 20°N are corrected (observations from 19 out of the 24 AMMA radiosonde network sites are affected). 3. Model setup The French numerical weather prediction (NWP) system is developed in collaboration with the European Centre for Medium-Range Weather Forecasts (ECMWF; Courtier et al. 1991 ). A four-dimensional variational data

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Peter Knippertz and Andreas H. Fink

, KF08 hypothesized that the strong extratropical influences may imply a comparably good predictability of such events that would allow a timely warning of the population and therefore a mitigation of detrimental impacts as well as an exploitation of beneficial effects. To test this hypothesis, the present study gives a statistical evaluation of boreal winter precipitation forecasts made by the 40-yr European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis project (ERA-40; Uppala et

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O. Bock and M. Nuret

(WAM) water cycle, and assess its representation in three largely used NWP models: the European Centre for Medium-Range Weather Forecasts-Integrated Forecast System (ECMWF-IFS), the National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis I [referred to as NCEP1; Kalnay et al. (1996) ], and the NCEP–Department of Energy (DOE) reanalysis II [referred to as NCEP2; Kanamitsu et al. (2002) ]. To this end, we use special observations collected

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

radiosonde network in August 2000 provided the most important source of information for an accurate representation of the African easterly jet (AEJ) in the European Centre for Medium-Range Weather Forecasts (ECMWF) analysis. The aim of this paper is to assess the impacts of the enhanced AMMA radiosonde network on the ECMWF analysis and forecast during August 2006 (i.e., within the peak of the monsoon season). To do this, observational system experiments (OSEs) were performed by comparing two scenarios

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

natural resting environment and the simulated surface climate from the Unified Model. The latest version of the New Dynamics Unified Model version 6.1 (UM6.1) developed at the Met Office was used both for the global scale (horizontal resolution of 40 km) and for a limited scale (horizontal resolution of 12 km; referred to as LAM hereafter). The model is initialized from the European Centre for Medium-Range Weather Forecasts (ECMWF) dump file, which is the assimilated ECMWF operational analysis, giving

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Adrian M. Tompkins and Laura Feudale

as the Prévisions Saisonnières en l’Afrique de l’Ouest (PRE-SAO). The dynamical models that contribute to this process include those issued from the Met Office, Météo-France, the International Research Institute for Climate and Society (IRI), the National Centers for Environmental Prediction (NCEP), and the European Centre for Medium-Range Weather Forecasts (ECMWF). While some attempts have been and continue to be made to directly validate the consensus forecast itself (e.g., Hamatan et al. 2004

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

clouds and over land surfaces. The assimilation of cloud-affected Special Sensor Microwave Imager (SSM/I) observations has been operational at the European Centre for Medium-Range Weather Forecasts (ECMWF) since June 2005 ( Bauer et al. 2006a , b ). Significant headway was made possible when a two-step method [one- and four-dimensional variational data assimilation (1D + 4DVAR)] was adopted to assimilate a selection of cloudy, sea SSM/I observations. In parallel, studies have been carried out in

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Fatima Karbou, Elisabeth Gérard, and Florence Rabier

al. (2006) . b. The assimilation system and the experiments This study is based on the Météo-France assimilation and forecast system (ARPEGE), which uses a 6-h time window and a multi-incremental 4DVAR scheme ( Courtier et al. 1994 ; Veersé and Thépaut 1998 ; Rabier et al. 2000 ). The ARPEGE system was developed in collaboration with European Centre for Medium-Range Weather Forecasts (ECMWF). The assimilation system seeks a state of the atmosphere that represents the optimal balance between

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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

.g., over southern Niger). A similar elongated structure is also present in the European Centre for Medium-Range Weather Forecasts (ECMWF) forecast, but it weakens significantly toward the northeast, and more rainfall is predicted over Nigeria. In this respect, the ECMWF forecast follows more closely the satellite rainfall estimate. National Centers for Environmental Prediction (NCEP) simulation lies between the two scenarios mentioned above, but it also predicts high rainfall rates over wide areas such

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Benjamin Sultan, Serge Janicot, and Cyrille Correia

( Mo 2001 ). The SSA ( Vautard and Ghil 1989 ; Vautard et al. 1992 ; Ghil et al. 2002 ) is related to empirical orthogonal functions (EOFs) but is applied to lagged time series providing SSA modes that correspond to intraseasonal oscillations in a frequency band. We apply SSA to rainfall amounts from three different sources: the Institut de Recherche pour le Developpement (IRD) rainfall dataset and the NCEP–National Center for Atmospheric Research (NCAR) reanalysis and the 40-yr European Centre

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