Nonlinear Processes in Geophysics www.nonlin-processes-geophys.net 1023-5809 1607-7946 15 1 2008 10.5194/npg-15-81-2008 http://www.nonlin-processes-geophys.net/15/81/2008/ http://www.nonlin-processes-geophys.net/15/81/2008/npg-15-81-2008.html http://www.nonlin-processes-geophys.net/15/81/2008/npg-15-81-2008.pdf 81 94 2008-02-08 An update on THORPEX-related research in data assimilation and observing strategies F. Rabier Florence.Rabier@meteo.fr P. Gauthier C. Cardinali R. Langland M. Tsyrulnikov A. Lorenc P. Steinle R. Gelaro K. Koizumi CNRM/GAME, Météo-France and CNRS, France Department of Earth and Atmospheric Sciences, UQAM, Montréal, Canada European Centre for Medium-range Weather Forecasts, Reading, UK Naval Research Laboratory, USA Hydrometeorological Research Centre of Russia, Russia The Met-Office, UK Bureau of Meteorology Research Centre, Australia NASA/Global Modelling and Assimilation Office, USA Japanese Meteorological Agency, Japan The international programme "THORPEX: a World Weather Research Programme" provides a framework in which to tackle the challenge of improving the forecast skill of high-impact weather through international collaboration between academic institutions, operational forecast centres, and users of forecast products. The objectives of the THORPEX Data Assimilation and Observation Strategy Working Group (DAOS-WG) are two-fold. 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