Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 15, 8401-8421, 2015
https://doi.org/10.5194/acp-15-8401-2015
© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
28 Jul 2015
Aerosol chemistry above an extended archipelago of the eastern Mediterranean basin during strong northern winds
E. Athanasopoulou1,2, A. P. Protonotariou2, E. Bossioli2, A. Dandou2, M. Tombrou2, J. D. Allan1,3, H. Coe1, N. Mihalopoulos4,5, J. Kalogiros4, A. Bacak1, J. Sciare6,7, and G. Biskos7,8,9 1School of Earth, Atmosphere and Environmental Sciences, University of Manchester, Manchester, M13 9PL, UK
2Department of Applied Physics, National and Kapodistrian University of Athens, 15784 Athens, Greece
3National Centre for Atmospheric Science, University of Manchester, Manchester, M13 9PL, UK
4Institute for Environmental Research and Sustainable Development, National Observatory of Athens, 15236 Athens, Greece
5Chemistry department, University of Crete, 71003 Heraklion, Crete, Greece
6Laboratoire des Sciences du Climat et de l'Environnement, LSCE, UMR8212, CNRS-CEA-UVSQ, 91191 Gif-sur-Yvette, France
7Energy Environment and Water Research Center, The Cyprus Institute, Nicosia, Cyprus
8Department of Environment, University of Aegean, 81100 Mytilene, Greece
9Faculty of Civil Engineering and Geosciences, Delft University of Technology, Delft, the Netherlands
Abstract. Detailed aerosol chemical predictions by a comprehensive model system (i.e. PMCAMx, WRF, GEOS-CHEM), along with airborne and ground-based observations, are presented and analysed over a wide domain covering the Aegean Archipelago. The studied period is 10 successive days in 2011, characterized by strong northern winds, which is the most frequently prevailing synoptic pattern during summer. The submicron aerosol load in the lower troposphere above the archipelago is homogenously enriched in sulfate (average modelled and measured submicron sulfate of 5.5 and 5.8 μg m−3, respectively), followed by organics (2.3 and 4.4 μg m−3) and ammonium (1.5 and 1.7 μg m−3). Aerosol concentrations smoothly decline aloft, reaching lower values (< 1 μg m−3) above 4.2 km altitude. The evaluation criteria rate the model results for sulfate, ammonium, chloride, elemental carbon, organic carbon and total PM10 mass concentrations as "good", indicating a satisfactory representation of the aerosol chemistry and precursors. Higher model discrepancies are confined to the highest (e.g. peak sulfate values) and lowest ends (e.g. nitrate) of the airborne aerosol mass size distribution, as well as in airborne organic aerosol concentrations (model underestimation ca. 50 %). The latter is most likely related to the intense fire activity at the eastern Balkan area and the Black Sea coastline, which is not represented in the current model application. The investigation of the effect of local variables on model performance revealed that the best agreement between predictions and observations occurs during high winds from the northeast, as well as for the area confined above the archipelago and up to 2.2 km altitude. The atmospheric ageing of biogenic particles is suggested to be activated in the aerosol chemistry module, when treating organics in a sufficient nitrogen and sulfate-rich environment, such as that over the Aegean basin. More than 70 % of the predicted aerosol mass over the Aegean Archipelago during a representative Etesian episode is related to transport of aerosols and their precursors from outside the modelling domain.

Citation: Athanasopoulou, E., Protonotariou, A. P., Bossioli, E., Dandou, A., Tombrou, M., Allan, J. D., Coe, H., Mihalopoulos, N., Kalogiros, J., Bacak, A., Sciare, J., and Biskos, G.: Aerosol chemistry above an extended archipelago of the eastern Mediterranean basin during strong northern winds, Atmos. Chem. Phys., 15, 8401-8421, https://doi.org/10.5194/acp-15-8401-2015, 2015.
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Short summary
A model system is evaluated versus ground and airborne aerosol measurements, towards the identification of its competencies and deficiencies over the eastern Mediterranean (EM) during summer. Secondary organic aerosol (OA) formation is investigated towards improving OA behaviour. Biomass burning is a significant particle source, largely explaining OA underestimation (ca. 50%). More than 70% of the aerosol mass over the EM is related to trans-boundary transport during strong northeastern winds.
A model system is evaluated versus ground and airborne aerosol measurements, towards the...
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