Articles | Volume 17, issue 20
Atmos. Chem. Phys., 17, 12509–12531, 2017

Special issue: CHemistry and AeRosols Mediterranean EXperiments (ChArMEx)...

Atmos. Chem. Phys., 17, 12509–12531, 2017

Research article 23 Oct 2017

Research article | 23 Oct 2017

Modelling organic aerosol concentrations and properties during ChArMEx summer campaigns of 2012 and 2013 in the western Mediterranean region

Mounir Chrit1, Karine Sartelet1, Jean Sciare2,7, Jorge Pey3,a, Nicolas Marchand3, Florian Couvidat4, Karine Sellegri5, and Matthias Beekmann6 Mounir Chrit et al.
  • 1CEREA, Joint Laboratory École des Ponts ParisTech – EDF R&D, Université Paris-Est, 77455 Champs-sur-Marne, France
  • 2LSCE, CNRS-CEA-UVSQ, IPSL, Université Paris-Saclay, Gif-sur-Yvette, France
  • 3Aix-Marseille University, CNRS, LCE UMR 7376, Marseille, France
  • 4INERIS, Verneuil-en-Halatte, France
  • 5Laboratoire de Météorologie Physique (LaMP), UMR 6016 CNRS/UBP, of the Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Aubière, France
  • 6LISA, UMR CNRS 7583, IPSL, Université Paris-Est Créteil and Université Paris Diderot, France
  • 7EEWRC, The Cyprus Institute, Nicosia, Cyprus
  • anow at: The Geological Survey of Spain, IGME, 50006 Zaragoza, Spain

Abstract. In the framework of the Chemistry-Aerosol Mediterranean Experiment, a measurement site was set up at a remote site (Ersa) on Corsica Island in the northwestern Mediterranean Sea. Measurement campaigns performed during the summers of 2012 and 2013 showed high organic aerosol concentrations, mostly from biogenic origin. This work aims to represent the organic aerosol concentrations and properties (oxidation state and hydrophilicity) using the air-quality model Polyphemus with a surrogate approach for secondary organic aerosol (SOA) formation. Biogenic precursors are isoprene, monoterpenes and sesquiterpenes. In this work, the following model oxidation products of monoterpenes are added: (i) a carboxylic acid (MBTCA) to represent multi-generation oxidation products in the low-NOx regime, (ii) organic nitrate chemistry and (iii) extremely low-volatility organic compounds (ELVOCs) formed by ozonolysis. The model shows good agreement of measurements of organic concentrations for both 2012 and 2013 summer campaigns. The modelled oxidation property and hydrophilic organic carbon properties of the organic aerosols also agree reasonably well with the measurements. The influence of the different chemical processes added to the model on the oxidation level of organics is studied. Measured and simulated water-soluble organic carbon (WSOC) concentrations show that even at a remote site next to the sea, about 64 % of the organic carbon is soluble. The concentrations of WSOC vary with the origins of the air masses and the composition of organic aerosols. The marine organic emissions only contribute to a few percent of the organic mass in PM1, with maxima above the sea.

Final-revised paper