Tuesday, 8 August 2000: 9:30 AM
In autumn 1999, the Special Observing Period of the Mesoscale Alpine Program (7 September 15 November 1999) took place over the Alps. One of
the main objectives was to investigate the mechanism of orographically induced heavy precipitation events with special emphasis on their dynamics,
microphysics and hydrological consequences. In this context, the French Ronsard research radar located near Milan was operated in coordination
with the Swiss SMA operational radar at Monte-Lema and the US NCAR S-POL Doppler and Polarimetric radar to provide multi-Doppler
observations over the windward slope of the Alps. Since the past studies on precipitating systems were conducted over flat terrains, the data
collected during the MAP/SOP provide a first opportunity to deduce three dimensional wind fields from Doppler data over mountainous regions. The
first results about radar-derived wind and precipitation fields permit to emphasize the influence of the orography-induced air circulation (slope winds)
on the structure and evolution of the observed precipitating systems. Also, this work permits to definitively insure the reliability of the procedure
developed by the authors for multi-Doppler analyses over complex terrain.
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