Physicochemical Characterization of Coastal Aerosols over the Mediterranean- Comparison with WRF-Chem Simulations

Estimation of the impact of atmospheric aerosols from global to local scales is an important scientific challenge. One of a major source of particles is constituted by the oceans through the generation of sea-spray aerosols (e.g., Huneeus et al., 2012). In coastal areas, marine aerosols can affect air quality (e.g., Knipping and Dabdub, 2003) through their ability to interact chemically and physically with other aerosol species and gases (Yoon et al. 2007). A better knowledge of the circulation of these aerosols over coastal sites is necessary to better understand how aerosols can affect coastal ecosystems. To this end, Tedeschi and Piazzola (2011) developed the numerical model MACMod (Marine Aerosol Concentration Model) to simulate aerosol dispersion at local scale over coastal areas. In particular, this model is suitable for implementation of chains of grid-nested models dedicated to a better understanding of the anthropogenic impact. In this study, the WRF-Chem model is used to provide the MACMod boundary and initial conditions. WRF-Chem is the Weather Research and Forecasting (WRF) model online-coupled with Chemistry for investigation of regional-scale air quality simulates the emission, transport, mixing, and chemical transformation of trace gases and aerosols simultaneously with the meteorology. To assess the performance of the coupling between WRF-Chem and MACMod, the present paper proposes a comparison between the physicochemical analysis of aerosol concentrations measured on different locations over the Mediterranean Sea and the model chain predictions. The results confirm the reliability of the sea-spray source formulation proposed by Demoisson et al. (2013) and the occurrence of the reaction between sea-spray and the organic matter present in the atmosphere frequently observed in the Mediterranean coast (Piazzola et al. 2012; 2015; Sellegri et al., 2001).