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Ann. Geophys., 25, 597-622, 2007
www.ann-geophys.net/25/597/2007/
© European Geosciences Union 2007
Investigation of the atmospheric boundary layer dynamics during the ESCOMPTE campaign
F. Saïd1, A. Brut2, B. Campistron1, and F. Cousin3
1Centre de Recherches Atmosphériques, UMR CNRS 5560, 8 route de Lannemezan, 65300 Campistrous, France
2Centre d'Etudes Spatiales de la BIOsphère UMR 5126, 18 avenue Edouard Belin, 31401 Toulouse Cedex 9, France
3Laboratoire d'Aérologie, UMR CNRS 5560, 14 avenue Edouard Belin, 31400 Toulouse, France
Abstract. This paper presents some results about the behavior of the atmospheric
boundary layer observed during the ESCOMPTE experiment. This campaign, which
took place in south-eastern France during summer 2001, was aimed at
improving our understanding of pollution episodes in relation to the
dynamics of the lower troposphere. Using a large data set, as well as a
simulation from the mesoscale non-hydrostatic model Meso-NH, we describe and
analyze the atmospheric boundary layer (ABL) development during two specific
meteorological conditions of the second Intensive Observation Period (IOP).
The first situation (IOP2a, from 22 June to 23 June) corresponds to moderate,
dry and cold northerly winds (end of Mistral event), coupled with a sea-breeze
in the lower layer, whereas sea-breeze events with weak southerly winds
occurred during the second part of the period (IOP2b, from 24 June to 26 June).
In this study, we first focus on the validation of the model outputs with a
thorough comparison of the Meso-NH simulations with fields measurements on
three days of the IOP: 22 June, 23 June and 25 June. We also investigate
the structure of the boundary layer on IOP2a when the Mistral is
superimposed on a sea breeze. Then, we describe the spatial and diurnal
variability of the ABL depths over the ESCOMPTE domain during the whole IOP.
This step is essential if one wants to know the depth of the layer where the
pollutants can be diluted or accumulated. Eventually, this study intends to
describe the ABL variability in relation to local or mesoscale dynamics
and/or induced topographic effects, in order to explain pollution transport
processes in the low troposphere.
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