X-Band Polarimetric & Doppler radar observations of heavy precipitation events over the Mediterranean region (France).
Résumé
Numerous heavy precipitations take place over the western Mediterranean Sea especially during summer and in some case lead to severe floods over the continent (Vaison la Romaine in 1992, Draguignan the 15-16 June 2010, Antibes 30 October-1 November 2010...). Since the Mediterranean is surrounded by mountain barriers, and strong contrasts between sea and continent exist, local forcing is important. The present work aims at examining the environmental conditions and precipitation structures of storms observed in these regions and at improving our knowledge about the life-cycle of the more intense events and processes that govern their evolution. It uses observations gathered by the X band polarimetric & Doppler weather Radar HYDRIX. This radar, owned by the LATMOS/CNRS, developed and operated by NOVIMET, collects in an operational way since 2008 reflectivity, Doppler and polarimetric data with a time step and a spatial resolution of 5 minutes and 1 km respectively. In addition to these data, derived products such as instantaneous rainfall, cumulated rain, cell displacement and hydrometeor classification are obtained in real time. It also provides Doppler information in clear air region. All these data can be used to document the low level environment and the internal dynamics, microphysics and the interaction-mechanisms (wind shear, ...) leading to high-accumulated surface rainfall. The presentation focus on the first step of this work devoted to the temporal and spatial characterisation of the precipitation that affects the Provencal and Ligurian region. A statistical and a spectral analysis are performed to construct a climatology and to document the life cycle and the dynamical-microphysical characteristics of a few representative high-impact events.
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