ECLAP experiment: observations of the boundary layer structure in Paris and its suburbs in anticyclonic conditions

The ECLAP experiment took place during the winter 1994-1995, in the region of Paris. Its primary goal was to collect an experimental data set allowing the determination of boundary layer parameters simultaneously in Paris and in its suburbs, for meteorological conditions favourable to high level of pollution and/or intense urban heat island. Both surface measurements (sonic anemometers, pyranometers) and teledetection measurements (sodars and backscattering lidars) have been performed over two sites, one near the center of Paris and one close to Palaiseau, a small town located at 25km south-west of Paris in a rural environment. Surface turbulent fluxes have been measured in Palaiseau with two sonic anemometers. Two, or four soundings (for the most interesting periods) performed by Meteo-France near Palaiseau are available for each day. Ten Intensive Observations Periods (IOP) have been completed between December 1994 and March 1995. The IOP10, during 13 March and 14 March 1995, has been selected as a first analysis period as presenting an interesting meteorological variability and disposing of a complete data set at all sites. In both days of this IOP, rural sites (Trappes and Palaiseau) are under influence of Paris's urban plume and heat island effect is important. Comparisons between different instruments and sites are shown for the description of synoptic situation, evolution of boundary layer height, and variations of surface heat fluxes.