TY - JOUR
T1 - Impact of the Rhône and Durance valleys on sea-breeze circulation in the Marseille area
AU - Bastin, Sophie
AU - Drobinski, Philippe
AU - Dabas, Alain
AU - Delville, Patricia
AU - Reitebuch, Oliver
AU - Werner, Christian
N1 - Funding Information:
This work was conducted at Service d'Aéronomie and Laboratoire de Météorologie Dynamique of the Institut Pierre Simon Laplace. The authors would like to thank the anonymous referees that helped to improve the manuscript significantly; R. Vautard, J.L. Caccia, B. Campistron, B. Bénech and V. Guénard for fruitful discussion; A. Delaval and M. Chiriaco for assistance in operating the Transportable Wind Lidar; C. Boitel and B. Romand for their technical assistance; J.F. Audureau for providing the sodar data; M.C Lanceau for help in collecting the referenced papers; and B. Cros and P. Durand for the coordination of the experiment. The ights of the DLR Falcon was funded partly by the CAATER (Co-ordinated Access to Aircraft for Transnational Environmental Research) program of the European Commission. We also like to thank E. Nagel (DLR) for assistance in operation of the WIND system, the pilots of the DLR ight facility R. Welser and M. Hinterwaldner, the Falcon technician and the great support of the CAATER facilator A. Giez (DLR).
PY - 2005/3/1
Y1 - 2005/3/1
N2 - Sea-breeze dynamics in the Marseille area, in the south of France, is investigated 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. Under particular attention in this paper is the sea-breeze channelling by the broad Rhône valley and the narrow Durance valley, both oriented nearly-north-south, i.e., perpendicular to the coastline, and its possible impact on the sea-breeze penetration, intensity and depth, which are key information for air pollution issues. One situation of slight synoptic pressure gradient leading to a northerly flow in the Rhône valley (25 June 2001) and one situation of a weak onshore prevailing synoptic wind (26 June 2001) are compared. The impact of the Rhône and Durance valleys on the sea-breeze dynamics on these two typical days is generalized to the whole ESCOMPTE observing period. The present study shows by combining simple scaling analysis with wind data from meteorological surface stations and Doppler lidars that (i) the Durance valley always affects the sea breeze by accelerating the flow. A consequence is that the Durance valley contributes to weaken the temperature gradient along the valley and thus the sea-breeze circulation. In some cases, the acceleration of the channelled flow in the Durance valley suppresses the sea-breeze flow by temperature gradient inhibition; (ii) the Rhône valley does not generally affect the sea breeze significantly. However, if the sea breeze is combined with an onshore flow, it leads to further penetration inland and intensification of the low-level southerly flow. In this situation, lateral constriction may accelerate the sea breeze. Simple scaling analysis suggests that Saint Paul (44.35°N, about 100 km from the coastline) is the lower limit where sea breeze can be affected by the Rhône valley. These conclusions have implications in air quality topics as channelled sea breeze may advect far inland pollutants which may be incorporated into long-range transport, particularly in the Durance valley.
AB - Sea-breeze dynamics in the Marseille area, in the south of France, is investigated 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. Under particular attention in this paper is the sea-breeze channelling by the broad Rhône valley and the narrow Durance valley, both oriented nearly-north-south, i.e., perpendicular to the coastline, and its possible impact on the sea-breeze penetration, intensity and depth, which are key information for air pollution issues. One situation of slight synoptic pressure gradient leading to a northerly flow in the Rhône valley (25 June 2001) and one situation of a weak onshore prevailing synoptic wind (26 June 2001) are compared. The impact of the Rhône and Durance valleys on the sea-breeze dynamics on these two typical days is generalized to the whole ESCOMPTE observing period. The present study shows by combining simple scaling analysis with wind data from meteorological surface stations and Doppler lidars that (i) the Durance valley always affects the sea breeze by accelerating the flow. A consequence is that the Durance valley contributes to weaken the temperature gradient along the valley and thus the sea-breeze circulation. In some cases, the acceleration of the channelled flow in the Durance valley suppresses the sea-breeze flow by temperature gradient inhibition; (ii) the Rhône valley does not generally affect the sea breeze significantly. However, if the sea breeze is combined with an onshore flow, it leads to further penetration inland and intensification of the low-level southerly flow. In this situation, lateral constriction may accelerate the sea breeze. Simple scaling analysis suggests that Saint Paul (44.35°N, about 100 km from the coastline) is the lower limit where sea breeze can be affected by the Rhône valley. These conclusions have implications in air quality topics as channelled sea breeze may advect far inland pollutants which may be incorporated into long-range transport, particularly in the Durance valley.
KW - Doppler lidar
KW - Sea breeze
KW - Valley flows
UR - https://www.scopus.com/pages/publications/14044266815
U2 - 10.1016/j.atmosres.2004.04.014
DO - 10.1016/j.atmosres.2004.04.014
M3 - Article
AN - SCOPUS:14044266815
SN - 0169-8095
VL - 74
SP - 303
EP - 328
JO - Atmospheric Research
JF - Atmospheric Research
IS - 1-4
ER -