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Communication incl. Poster: BibTeX citation key:  Cazenave
Cazenave, F. & Gosset, M. 2009. High resolution rainfield at the mesoscale: Review of results and radar based methods in Djougou and Niamey areas. Work presented at Third International AMMA Conference, July 20—24, at Ouagadougou, Burkina Faso.
Added by: Devic 2009-10-06 11:20:44    Last Edited by: roussot 2009-10-16 16:29:29
Categories: General
Keywords: Hydrology, Precipitation
Creators: Cazenave, Gosset
Publisher: African Monsoon Multidisciplinary Analyses (Ouagadougou, Burkina Faso)
Collection: Third International AMMA Conference

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During the AMMA campaign, three transportable research radars have been operated over the Niamey (Niger) and Oueme (Benin) meso-scale catchments in order to provide high resolution rainfall maps. For transportability purposes, these research radars operate at relatively high frequencies (5 GHz and 10 GHz) where the signal is subject to attenuation by rain. The problem is acute in the Tropics where heavy rainfall are encountered. Several methods have been proposed and implemented to correct for attenuation and provide a quantitative estimation of precipitation. One successful new technique is the use of polarimetry to overcome the attenuation problem. Thanks to the AMMA campaign, these methods have been tested for the first time in West african heavy rainfall.
The data set discussed here covers the 2006 and 2007 rainy seasons and was provided by the MIT Doppler C-band radar which was operating in Niger and Xport, a polarimetric X-band radar which was operating in Benin. In both areas, dense networks of rain gages, each spread over a region of approximately 1° by 1°, were available within the radar coverages as part of the AMMA-CATCH observing System.
The presentation will discuss the accuracy and the limitations of the high resolution rainfields that can be derived from radar for several derivation methods. The evaluation will be based on radar/ rain gages comparison over the 53 to 56 gages available in both zone. The range dependence of radar accuracy and the stability of the results within the season will be discussed. Direct comparison of the radar and rain gages time series above the gages at 10 min time steps as well as time or space integrated products will be evaluated in order to assess the quality of the radar products and their scale dependence.
Last Edited by: roussot