The representation of dust transport and missing urban sources as major issues for the simulation of PM episodes in a Mediterranean area
1LISA, CMC, avenue du Général de Gaulle, 94010 Créteil Cedex, France
2AtmoPACA, 146 rue Paradis, 13006 Marseille, France
*now at: LATMOS, IPSL, Université Pierre et Marie Curie, CNRS, Paris, France
Abstract. Due to its adverse effects on human health, atmospheric particulate matter (PM) constitutes a growing challenge for air quality management. It is also a complex subject of study. The understanding of its atmospheric evolution is indeed made difficult by the wide number of sources and the numerous processes that govern its evolution in the troposphere. As a consequence, the representation of particulate matter in chemistry-transport models needs to be permanently evaluated and enhanced in order to refine our comprehension of PM pollution events and to propose consistent environmental policies. The study presented here focuses on a summer particulate pollution episode that occurred on the French Mediterranean coast. It aims at identifying the constitutive elements of this episode and to discuss its representation within a eulerian model. We first highlight the major role of dust transport from western Africa in the formation of a multi-day PM event.
This result shows that dust import has to be regarded as a potentially major participant to PM events in Europe, even when considering moderate peak values. In parallel we focus on a lack of diurnal variability in the model, which is attributed to missing urban sources in standard emission inventories, and notably the resuspension of particles by urban road traffic. Through a sensitivity study based on PM and NOx measurements, we could assess the amplitude of this lack as well as the need to reconsider road traffic PM sources. In parallel, by coupling the CHIMERE-DUST model outputs to our simulation, we could show that the representation of transcontinental dust transport is a necessity for a better simulation of atmospheric particles in Southern Europe, and – in the frame of air quality management – for the quantification of the anthropogenic part of particulate matter pollution.