HR: 12:05h
AN: A42A-08    [Abstracts]
TI: Sodar and Lidar Observations and Modelling of the Pollutants Dynamics in a Strongly Industrialized Coastal Area during a Sea-Breeze Event
AU: * Talbot, C
EM: talbot@univ-littoral.fr
AF: Universite du Littoral de la Cote d Opale, CNRS FRE 2816, ELICO, Maison de la Recherche en Environnement Naturel, 32 avenue Foch, Wimereux, 62930, France
AU: Leroy, C
EM: celine.leroy@univ-littoral.fr
AF: Universite du Littoral de la Cote d Opale, CNRS UMR 8101, LPCA, Maison de la Recherche en Environnement Industriel, Dunkerque, 59140, France
AU: Augustin, P
EM: patrick.augustin@univ-littoral.fr
AF: Universite du Littoral de la Cote d Opale, CNRS UMR 8101, LPCA, Maison de la Recherche en Environnement Industriel, Dunkerque, 59140, France
AU: Willart, V
EM: veronique.willart@univ-littoral.fr
AF: Universite du Littoral de la Cote d Opale, CNRS FRE 2816, ELICO, Maison de la Recherche en Environnement Naturel, 32 avenue Foch, Wimereux, 62930, France
AU: Delbarre, H
EM: hdelbarr@univ-littoral.fr
AF: Universite du Littoral de la Cote d Opale, CNRS UMR 8101, LPCA, Maison de la Recherche en Environnement Industriel, Dunkerque, 59140, France
AU: khomenko, G
EM: khomenko@univ-littoral.fr
AF: Universite du Littoral de la Cote d Opale, CNRS FRE 2816, ELICO, Maison de la Recherche en Environnement Naturel, 32 avenue Foch, Wimereux, 62930, France
AB: The understanding of the atmospheric dynamics under sea breeze is crucial for predicting pollution transport and dispersion in coastal areas. We present here a study of the boundary-layer dynamics and the redistribution of the industrial SO2 emissions in the Dunkerque region (51 N, 2.20 E), in the north of France, at the eastern limit of the English Channel. The French Flanders coastal area is strongly industrialized with many refineries and metallurgic factories. This region is a flat area with small hills (up to 200 meters high) located 30 km away from the coast where sea breezes develop frequently all along the year. Thus, the pollutants transport and pollution episodes are mainly governed by the sea-breeze phenomenon under sunny days. By using optical and acoustic remote-sensing instruments (lidar and sodar), the vertical structure of the atmospheric boundary layer has been observed during a whole sea-breeze event in September 2003. The structure and dynamics of the atmosphere and the pollutants transport within has been simulated with a 3D non hydrostatic model Meso-NHC, developed by the C.R.N.M. and Laboratoire d Aerologie, and was compared with the remote-sensing observations. We present the results of our numerical simulations as well as the data of the remote sensing instruments and stations of the air quality network. The thermal internal boundary layer, the gravity current, the atmospheric boundary layer, the nocturnal boundary layer and the residual layer, were observed by the remote sensing instruments and computed by the model. High values of SO2 concentration were observed at the sea-breeze front passage, and the pollutants emitted were uplifted by updrafts in the front. The acceleration of the sea-breeze flow seems to be responsible of the vertical redistribution of the pollutants emitted inside the sea-breeze system by means of vertical ascents in the sea-breeze front. High values of SO2 concentrations computed in the model were accumulating at the vicinity of the sea-breeze gravity current, whose height was determined by sodar, and at the altitude of which the lidar detected a layer of high reflectivity. The polluted air mass, above the sea and the gravity current and which was containing the pollutants emitted from the industrial area, seemed to turned lately in a stable multilayered structure. Such dynamical conditions are keen to enhance the concentration of secondary pollutants during sunny days, as suggested by the vertical profiles of ozone concentration measured by the lidar.
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0368 Troposphere: constituent transport and chemistry
DE: 0394 Instruments and techniques
DE: 0466 Modeling
DE: 0478 Pollution: urban, regional and global (0345, 4251)
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly