Aerosol modelling in Europe with a focus on Switzerland during summer and winter episodes

Abstract

This paper describes aerosol modelling in Europe with a focus on Switzerland during summer and winter periods. We modelled PM<sub>2.5</sub> (particles smaller than 2.5 μm in aerodynamic diameter) for one summer and two winter periods in years 2006 and 2007 using the MM5/CAMx air quality model system. The detailed AMS (aerosol mass spectrometer) measurements at specific locations were used to evaluate the model results. In addition to the base case simulations, we carried out sensitivity tests with modified aerosol precursor emissions, air temperature and deposition. Aerosol concentrations in winter 2006 were twice as high as those in winter 2007, however, the chemical compositions were similar. CAMx could reproduce the relative composition of aerosols very well both in the winter and summer periods. Absolute concentrations of aerosol species were underestimated by about 20%. Both measurements and model results suggest that organic aerosol (30–38%) and particulate nitrate (30–36%) are the main aerosol components in winter. In summer, organic aerosol dominates the aerosol composition (55–57%) and is mainly of secondary origin. The contribution of biogenic volatile organic compound (BVOC) emissions to the formation of secondary organic aerosol (SOA) was predicted to be very large (>95%) in Switzerland. The main contributors to the modelled SOA concentrations were oxidation products of monoterpenes and sesquiterpenes as well as oligomerization of oxidized compounds. The fraction of primary organic aerosol (POA) derived from measurements was lower than the model predictions indicating the importance of volatility of POA, which has not yet been taken into account in CAMx. Sensitivity tests with reduced NO<sub>x</sub> and NH<sub>3</sub> emissions suggest that aerosol formation is more sensitive to ammonia emissions in winter in a large part of Europe. In Switzerland however, aerosol formation is predicted to be NO<sub>x</sub>-sensitive. In summer, effects of NO<sub>x</sub> and NH<sub>3</sub> emission reductions on aerosol concentrations are predicted to be lower mostly due to lower ammonium nitrate concentrations. In general, the sensitivity to NH<sub>3</sub> emissions is weaker in summer due to higher NH<sub>3</sub> emissions

Seasonal and meteorological impacts on primary spontaneous pneumothorax

“…Rather, increase in wind speed can induce increase in inhalational exposure to pollen, allergens and air pollutants (36), leading to bronchiolar spasms and air trapping inside the blebs or bullae with a check valve mechanism (3,6,33). Perturbations in wind speed, rather than wind speed itself, cause dispersion of aerosol and drive atmospheric instability (37)(38)(39); this may be why variations in wind speed were associated with PSP in the present study. The relationship between changes in wind speed and PSP remained significant when including PSP events in smokers, whereas it diminished among PSP in non-smokers.…”

Regional Modeling of Aerosol Chemical Composition at the Puy de Dôme (France)

“…As AMS-observed NR-PM 1 mass concentration is compared to the simulated PM 2.5 in the following, the models are expected to give an overestimation of aerosol mass concentration. The difference between PM 1 and PM 2.5 mass concentrations can be high (previous studies report PM 1 /PM 2.5 mass ratios between 55 and 75%) and can vary according to the meteorological conditions and the emission rates of chemical compounds (Aksoyoglu et al, 2011;Spindler et al, 2013). However, the proportions of the predominant chemical components in NR-PM 1 and simulated PM 2.5 are expected to be of the same order.…”

“…Several authors have also mentioned lateral boundary conditions for aerosols as a source of uncertainties. Aksoyoglu et al (2011) concluded that the CAMx model reproduced the relative composition of aerosols very well over Switzerland but underestimated the absolute concentration by 20%. validated the online-coupled WRF/CHEM model against ground-based measurements over Europe.…”