Project Summary

In areas with large industrial agglomerations, like Marseille, high temperatures in summer and high emission rates of ozone precursors (nitric oxides and volatile organic compounds, VOC from anthropogenic and biogenic sources) favour the development of summer smog episodes. Therefore, the experiment ESCOMPTE was performed in the area of Marseille in summer 2001, the main objective being to establish a detailed 4-D data set including air chemical and meteorological data during high pollution events.
In coastal regions, as valid for the surrounding of Marseille, the meteorological conditions are a combination of large-scale flow and mesoscale circulation systems, like sea breezes, slope and valley winds. The latter are caused by non-homogeneous surface conditions which leads to spatial differences in the energy balance and, finally, in differences in spatial surface temperature which drives the circulation systems. Therefore, besides the monitoring of ozone and its precursors, detailed observations of the spatial distribution and temporal evolution of the meteorological conditions have been performed during the campaign in 2001 in the area of Marseille.
The IMK contributed to the experiment with two radiosounding systems in the Rhone valley and the Durance valley, one sodar, one energy-balance station and trace gas monitors in the Durance valley. Additionally the DO 128 aircraft was operated in the ESCOMPTE area, measuring the relevant air-chemical and meteorological parameters. The IMK research activities focused on the spatial differences between the coast and the mountain sites of (i) the energy balance of the earth surface, (ii) the near-surface temperature and humidity field, (iii) the turbulent fluxes of heat, moisture and air pollutants in the planetary boundary layer (PBL) and (iv) the horizontal mesocsale transport auf air pollutants as well as the exchange processes between the PBL and the free troposphere.

Energy balance station in the Durance valley

Industrial agglomeration with sewage ponds at the Mediterranean coast near Marseille, seen from the research aircraft DO 128.

Air pollution within the atmospheric boundary layer at the Mediterranean coast near Marseille during ESCOMPTE