On the relationship between water vapor field evolution and Precipitation systems lifecycle

The COPS (Convective Orographically-induced Precipitation Study) international field campaign took place in the summer of 2007 from June to August, in the region of South-West Germany / North-East France from the Vosges Mountains to the Black Forest Mountains, and across the Rhine Valley. The overall objective of the COPS campaign is to improve the Quantitative Precipitation Forecasts (QPF) skill of Numerical Weather Prediction (NWP) models over mid-range mountainous terrain. To achieve this goal, a large set of in-situ and remote sensing instrumentation was deployed over a series of super sites at selected locations across the domain of interest, while numerous operational and research models were run to assess their performances regarding the studied events observed during Intensive Operation Periods (IOP's). The focus of this presentation is on the preliminary investigation of the relationship that can be found between the precipitation systems, from initiation to decay and in their intensity and structure changes, and the associated water vapor field evolution. In particular, we will consider water vapor retrieval through GPS tomography and confront it with precipitation systems monitoring with ground based radars. These instruments operated at different wavelength (at C and X bands) and with different resolution capabilities, both in time and space offer, unmatched and complementary mean to study the precipitation system structure and evolution. Some of the underlying questions of this work deal with the role of water vapor as a precursor of convetive initiation and/or tracer of precipitation activity, with the effect of orography on the water vapor field distribution and evolution, with the necessity (or not?) of water vapor convergence to start convective activity or foster precipitation system enhancement, etc., while we can categorize precipitation lifecycle behavior with respect to orography influence.