Monday, 17 June 2002
Analysis of IOP2b land-sea breeze case during the ESCOMPTE experiment
Ground-based remote sensors (wind profilers, Doppler lidar), rawinsonde and surface station network and the French-German airborne Doppler lidar WIND have been used in the framework of the ESCOMPTE program (see http://medias.obs-mip.fr/escompte) to investigate the sea breeze along the South French coast at Marseille. This instrumentation allows to make the retrieval of the three-dimensional wind field as a function of time. The combination of these two instruments provide complementary data which are essential to determine the differents parameters (return flow height, land-sea breeze penetration
distance,...), which characterize the sea breeze phenomenon. Observations during IOP2 clearly show the existence of a strong north-westerly (coast-parallel)
synoptic forcing wind. A east-north/easterly (cross-coast) compensatory return flow appears at about 1 km height. The WIND data give us access to the landward extent of the sea breeze (about 150 km from the coast line). In this paper,
first results are given that show how topography, synoptic wind interacts with the sea breeze phenomenon and how boundary layer and return flow height are linked. In addition to the presence of a low-level land-see breeze flow, mountain waves of 30-40 km wavelength generated from the interaction of the strong north-westerly flow with the Alpine ridge are evidenced above the Mediterranean.
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