Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 17, 7891-7915, 2017
https://doi.org/10.5194/acp-17-7891-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
30 Jun 2017
Optical, physical and chemical properties of aerosols transported to a coastal site in the western Mediterranean: a focus on primary marine aerosols
Marine Claeys1, Greg Roberts1,2, Marc Mallet1, Jovanna Arndt3, Karine Sellegri4, Jean Sciare5,6, John Wenger3, and Bastien Sauvage7 1CNRM, Centre National de Recherches Météorologiques UMR3589, Météo-France/CNRS, Toulouse, France
2Scripps Institution of Oceanography, Center for Atmospheric Sciences and Physical Oceanography, La Jolla, USA
3Department of Chemistry and Environmental Research Institute, University College Cork, Cork, Ireland
4LaMP, Laboratoire de Météorologie Physique CNRS UMR6016, Observatoire de Physique du Globe de Clermont-Ferrand, Université Blaise Pascal, Aubière, France
5LSCE, Laboratoire des Sciences du Climat et de l'Environnement, Unité Mixte CEA-CNRS-UVSQ, CEA/Orme des Merisiers, 91191 Gif-sur-Yvette, France
6Energy Environement Water Research Center, The Cyprus Institute, 2121 Nicosia, Cyprus
7LA, Laboratoire d'Aérologie, Observatoire Midi-Pyrénées, CNRS/IRD/Université de Toulouse, 14, Avenue Édouard Belin, 31400 Toulouse, France
Abstract. As part of the ChArMEx-ADRIMED campaign (summer 2013), ground-based in situ observations were conducted at the Ersa site (northern tip of Corsica; 533 m a.s.l.) to characterise the optical, physical and chemical properties of aerosols. During the observation period, a major influence of primary marine aerosols was detected (22–26 June), with a mass concentration reaching up to 6.5 µg m−3 and representing more than 40 % of the total PM10 mass concentration. Its relatively low ratio of chloride to sodium (average of 0.57) indicates a fairly aged sea salt aerosol at Ersa. In this work, an original data set, obtained from online real-time instruments (ATOFMS, PILS-IC) has been used to characterise the ageing of primary marine aerosols (PMAs). During this PMA period, the mixing of fresh and aged PMAs was found to originate from both local and regional (Gulf of Lion) emissions, according to local wind measurements and FLEXPART back trajectories. Two different aerosol regimes have been identified: a dust outbreak (dust) originating from Algeria/Tunisia, and a pollution period with aerosols originating from eastern Europe, which includes anthropogenic and biomass burning sources (BBP). The optical, physical and chemical properties of the observed aerosols, as well as their local shortwave (SW) direct radiative effect (DRE) in clear-sky conditions, are compared for these three periods in order to assess the importance of the direct radiative impact of PMAs compared to other sources above the western Mediterranean Basin.

As expected, AERONET retrievals indicate a relatively low local SW DRF during the PMA period with mean values of −11 ± 4 at the surface and −8 ± 3 W m−2 at the top of the atmosphere (TOA). In comparison, our results indicate that the dust outbreak observed at our site during the campaign, although of moderate intensity (AOD of 0.3–0.4 at 440 nm and column-integrated SSA of 0.90–0.95), induced a local instantaneous SW DRF that is nearly 3 times the effect calculated during the PMA period, with maximum values up to −40 W m−2 at the surface. A similar range of values were found for the BBP period to those during the dust period (SW DRF at the surface and TOA of −23 ± 6 and −15 ± 4 W m−2 respectively).

The multiple sources of measurements at Ersa allowed the detection of a PMA-dominant period and their characterisation in terms of ageing, origin, transport, optical and physical properties and direct climatic impact.


Citation: Claeys, M., Roberts, G., Mallet, M., Arndt, J., Sellegri, K., Sciare, J., Wenger, J., and Sauvage, B.: Optical, physical and chemical properties of aerosols transported to a coastal site in the western Mediterranean: a focus on primary marine aerosols, Atmos. Chem. Phys., 17, 7891-7915, https://doi.org/10.5194/acp-17-7891-2017, 2017.
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Short summary
Over a period of 5 days (summer 2013), the mass concentration of primary marine aerosols was dominant compared to other aerosols measured at a ground-based measuring site on Corsica. The characteristics of primary marine aerosols such as their size distribution, their optical properties and their direct radiative effect were studied as a function of their ageing and region of emission. These characteristics were compared to two other periods dominated by different aerosol regimes.
Over a period of 5 days (summer 2013), the mass concentration of primary marine aerosols was...
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