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Intercomparison and evaluation of global aerosol microphysical properties among AeroCom models of a range of complexity
Many of the next generation of global climate models will include aerosol schemes which explicitly simulate the microphysical processes that determine the particle size distribution. These models enable aerosol optical properties and cloud condensation nuclei (CCN) concentrations to be determined by fundamental aerosol processes, which should lead to a more physically based simulation of aerosol direct and indirect radiative forcings. This study examines the global variation in particle size distribution simulated by 12 global aerosol microphysics models to quantify model diversity and to identify any common biases against observations. Evaluation against size distribution measurements from a new European network of aerosol supersites shows that the mean model agrees quite well with the observations at many sites on the annual mean, but there are some seasonal biases common to many sites. In particular, at many of these European sites, the accumulation mode number concentration is biased low during winter and Aitken mode concentrations tend to be overestimated in winter and underestimated in summer. At high northern latitudes, the models strongly underpredict Aitken and accumulation particle concentrations compared to the measurements, consistent with previous studies that have highlighted the poor performance of global aerosol models in the Arctic. In the marine boundary layer, the models capture the observed meridional variation in the size distribution, which is dominated by the Aitken mode at high latitudes, with an increasing concentration of accumulation particles with decreasing latitude. Considering vertical profiles, the models reproduce the observed peak in total particle concentrations in the upper troposphere due to new particle formation, although modelled peak concentrations tend to be biased high over Europe. Overall, the multi-model-mean data set simulates the global variation of the particle size distribution with a good degree of skill, suggesting that most of the individual global aerosol microphysics models are performing well, although the large model diversity indicates that some models are in poor agreement with the observations. Further work is required to better constrain size-resolved primary and secondary particle number sources, and an improved understanding of nucleation and growth (e.g. the role of nitrate and secondary organics) will improve the fidelity of simulated particle size distributions
Changes in concentration and size distribution of aerosols during fog over the south Indian Ocean
Effect of relative humidity on the aerodynamic diameter and respiratory deposition of fungal spores
Sources and atmospheric processing of size segregated aerosol particles revealed by stable carbon isotope ratios and chemical speciation
Size-segregated aerosol particles were collected during winter sampling campaigns at a coastal (55 degrees 37' N, 21 degrees 03'E) and an urban (54 degrees 64' N, 25 degrees 18' E) site. Organic compounds were thermally desorbed from the samples at different temperature steps ranging from 100 degrees C to 350 degrees C. The organic matter (OM) desorbed at each temperature step is analysed for stable carbon isotopes using an isotope ratio mass spectrometer (IRMS) and for individual organic compounds using a Proton Transfer Reaction Time-of-Flight Mass Spectrometer (PTR-MS). The OM desorbed at temperature
Number size distributions and seasonality of submicron particles in europe 2008â2009
Two years of harmonized aerosol number size distribution data from 24 European field monitoring sites have been analysed. The results give a comprehensive overview of the European near surface aerosol particle number concentrations and number size distributions between 30 and 500 nm of dry particle diameter. Spatial and temporal distribution of aerosols in the particle sizes most important for climate applications are presented. We also analyse the annual, weekly and diurnal cycles of the aerosol number concentrations, provide log-normal fitting parameters for median number size distributions, and give guidance notes for data users. Emphasis is placed on the usability of results within the aerosol modelling community
Fossil and non-fossil source contributions to atmospheric carbonaceous aerosols during extreme spring grassland fires in Eastern Europe
In early spring the Baltic region is frequently affected by
high-pollution events due to biomass burning in that area. Here we present a
comprehensive study to investigate the impact of biomass/grass burning (BB)
on the evolution and composition of aerosol in Preila, Lithuania, during
springtime open fires. Non-refractory submicron particulate matter
(NR-PM<sub>1</sub>) was measured by an Aerodyne aerosol chemical speciation
monitor (ACSM) and a source apportionment with the multilinear engine (ME-2)
running the positive matrix factorization (PMF) model was applied to the
organic aerosol fraction to investigate the impact of biomass/grass burning.
Satellite observations over regions of biomass burning activity supported
the results and identification of air mass transport to the area of
investigation. Sharp increases in biomass burning tracers, such as
levoglucosan up to 683âŻngâŻm<sup>â3</sup> and black carbon (BC) up to 17âŻÂ”gâŻm<sup>â3</sup>
were observed during this period. A further separation between
fossil and non-fossil primary and secondary contributions was obtained by
coupling ACSM PMF results and radiocarbon (<sup>14</sup>C) measurements of the
elemental (EC) and organic (OC) carbon fractions. Non-fossil organic carbon
(OC<sub>nf</sub>) was the dominant fraction of PM<sub>1</sub>, with the primary
(POC<sub>nf</sub>) and secondary (SOC<sub>nf</sub>) fractions contributing 26â44âŻ% and
13â23âŻ% to the total carbon (TC), respectively. 5â8âŻ% of the TC had a
primary fossil origin (POC<sub>f</sub>), whereas the contribution of fossil
secondary organic carbon (SOC<sub>f</sub>) was 4â13âŻ%. Non-fossil EC
(EC<sub>nf</sub>) and fossil EC (EC<sub>f</sub>) ranged from 13â24 and 7â13âŻ%,
respectively. Isotope ratios of stable carbon and nitrogen isotopes were
used to distinguish aerosol particles associated with solid and liquid
fossil fuel burning
Isolation and characterisation of Beauveria bassiana isolates from phylloplanes of hedgerow vegetation
Number size distributions and seasonality of submicron particles in Europe 2008-2009
Two years of harmonized aerosol number size distribution data from 24 European field monitoring sites have been analysed. The results give a comprehensive overview of the European near surface aerosol particle number concentrations and number size distributions between 30 and 500 nm of dry particle diameter. Spatial and temporal distribution of aerosols in the particle sizes most important for climate applications are presented. We also analyse the annual, weekly and diurnal cycles of the aerosol number concentrations, provide log-normal fitting parameters for median number size distributions, and give guidance notes for data users. Emphasis is placed on the usability of results within the aerosol modelling community. <br></br> We also show that the aerosol number concentrations of Aitken and accumulation mode particles (with 100 nm dry diameter as a cut-off between modes) are related, although there is significant variation in the ratios of the modal number concentrations. Different aerosol and station types are distinguished from this data and this methodology has potential for further categorization of stations aerosol number size distribution types. <br></br> The European submicron aerosol was divided into characteristic types: Central European aerosol, characterized by single mode median size distributions, unimodal number concentration histograms and low variability in CCN-sized aerosol number concentrations; Nordic aerosol with low number concentrations, although showing pronounced seasonal variation of especially Aitken mode particles; Mountain sites (altitude over 1000 m a.s.l.) with a strong seasonal cycle in aerosol number concentrations, high variability, and very low median number concentrations. Southern and Western European regions had fewer stations, which decreases the regional coverage of these results. Aerosol number concentrations over the Britain and Ireland had very high variance and there are indications of mixed air masses from several source regions; the Mediterranean aerosol exhibit high seasonality, and a strong accumulation mode in the summer. The greatest concentrations were observed at the Ispra station in Northern Italy with high accumulation mode number concentrations in the winter. The aerosol number concentrations at the Arctic station Zeppelin in Ny-AA lesund in Svalbard have also a strong seasonal cycle, with greater concentrations of accumulation mode particles in winter, and dominating summer Aitken mode indicating more recently formed particles. Observed particles did not show any statistically significant regional work-week or weekday related variation in number concentrations studied. <br></br> Analysis products are made for open-access to the research community, available in a freely accessible internet site. The results give to the modelling community a reliable, easy-to-use and freely available comparison dataset of aerosol size distributions
Number size distributions and seasonality of submicron particles in Europe 2008â2009
Two years of harmonized aerosol number size distribution data from 24 European field monitoring sites have been analysed.
The results give a comprehensive overview of the European near surface aerosol particle number concentrations and number size distributions between 30 and 500 nm of dry particle diameter. Spatial and temporal distribution of aerosols in the particle sizes most important for climate applications are presented. We also analyse the annual, weekly and diurnal cycles of the aerosol number concentrations, provide log-normal fitting parameters for median number size distributions, and give guidance notes for data users. Emphasis is placed on the usability of results within the aerosol modelling community.JRC.H.2-Air and Climat