Synoptic scale motions and convective forcing at lower mountains: Different remote sensing perspectives during the three months of COPS-2007 (Invited)

The Convection and Orographically-induced Precipitation Study (COPS) of WMO/WWRP had its field phase from 1 June to 31 August 2007. Of special interest was a 300 km x 200 km area shared by France, Germany and Switzerland, which contains large parts of the low mountain ranges Vosges, Jura and Black Forest around the Upper-Rhine rift-valley. The typical difference in topographic heights lies in the order of 1000 m.

Over the entire period the upstream weather patterns contained numerous south-bound cold-air-outbreaks over the Atlantic, inducing many highly transient south-westerly flow situations towards the COPS area. These are systematically visualized by multi-spectral time-lapse imagery of SEVIRI images from the geostationary Meteosat satellite (image interval: 15 min.; speed-up up to 36,000-fold). Rapid-scan loops (5 min intervals) for some intensive observations periods (IOPs) are used to reveal motion details. User determined presentation speed and the use of a weather map stereographic projection allows for a precise identification of cloud generation and motion in space and time.

For prominent IOPs, the synoptic satellite perspective is complemented with data-curtains of horizontal wind and water vapour obtained from two airbourne laser systems during the clear air initiation phase of convective events. The generation and propagation of the ensuing precipitation fields are documented by a polarimetric Doppler-radar deployed close to Strasbourg.

As one of its aims, the presentation intends to provide all experimentalists and modellers, who analyse COPS-IOPs, with readily accessible and scale dependent views of the atmospheric motions around the area and period of their specific interest.