|
|
 |
|
|
Ann. Geophys., 24, 1783-1799, 2006
www.ann-geophys.net/24/1783/2006/
© European Geosciences Union 2006
Variability of three-dimensional sea breeze structure in southern France: observations and evaluation of empirical scaling laws
P. Drobinski1, S. Bastin1, A. Dabas2, P. Delville3, and O. Reitebuch4
1Institut Pierre Simon Laplace/Service d’Aéronomie, Université Pierre et Marie Curie, Paris, France
2Centre National de Recherches Météorologiques, Météo-France, Toulouse, France
3Institut National des Sciences de l’Univers, Division Technique, Meudon, France
4Institut für Physik der Atmosphäre, Deutsches Zentrum für Luft- und Raumfahrt, Oberpfaffenhofen, Germany
Abstract. Sea-breeze dynamics in southern France is investigated using an airborne
Doppler lidar, a meteorological surface station network and radiosoundings,
in the framework of the ESCOMPTE experiment conducted during summer 2001 in
order to evaluate the role of thermal circulations on pollutant transport and
ventilation. The airborne Doppler lidar WIND contributed to three-dimensional
(3-D) mapping of the sea breeze circulation in an unprecedented way. The data allow
access to the onshore and offshore sea breeze extents (xsb), and to the
sea breeze depth (zsb) and intensity (usb). They also show that the
return flow of the sea breeze circulation is very seldom seen in this area
due to (i) the presence of a systematic non zero background wind, and (ii)
the 3-D structure of the sea breeze caused by the complex
coastline shape and topography. A thorough analysis is conducted on the
impact of the two main valleys (Rhône and Durance valleys) affecting the
sea breeze circulation in the area.
Finally, this dataset also allows an evaluation of the existing scaling laws
used to derive the sea breeze intensity, depth and horizontal extent. The
main results of this study are that (i) latitude, cumulative heating and
surface friction are key parameters of the sea breeze dynamics; (ii) in
presence of strong synoptic flow, all scaling laws fail in predicting the sea
breeze characteristics (the sea breeze depth, however being the most
accurately predicted); and (iii) the ratio zsb/usb is approximately
constant in the sea breeze flow.
Full Article in PDF (1918 KB) |
|
|
