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Natural aerosols are an important, yet understudied, part of the Arctic climate system. Natural marine biogenic aerosol components (e.g., methanesulfonic acid, MSA) are becoming increasingly important due to changing environmental conditions. In this study, we combine in situ aerosol observations with atmospheric transport modeling and meteorological reanalysis data in a data-driven framework with the aim to (1) identify the seasonal cycles and source regions of MSA, (2) elucidate the relationships between MSA and atmospheric variables, and (3) project the response of MSA based on trends extrapolated from reanalysis variables and determine which variables are contributing to these projected changes. We have identified the main source areas of MSA to be the Atlantic and Pacific sectors of the Arctic. Using gradient-boosted trees, we were able to explain 84% of the variance and find that the most important variables for MSA are indirectly related to either the gas- or aqueous-phase oxidation of dimethyl sulfide (DMS): shortwave and longwave downwelling radiation, temperature, and low cloud cover. We project MSA to undergo a seasonal shift, with non-monotonic decreases in April/May and increases in June-September, over the next 50 years. Different variables in different months are driving these changes, highlighting the complexity of influences on this natural aerosol component. Although the response of MSA due to changing oceanic variables (sea surface temperature, DMS emissions, and sea ice) and precipitation remains to be seen, here we are able to show that MSA will likely undergo a seasonal shift solely due to changes in atmospheric variables. [ABSTRACT FROM AUTHOR]

The characterization of the day-to-night changes of the atmospheric particle chemical and optical properties in autumn–winter (AW) and spring–summer (SS) is the main goal of this study to contribute to the characterization and understanding of the particulate matter (PM) impact on the environment and climate at one of the most vulnerable areas of the planet to climate change. To this end, PM10 and PM2.5 samples from 14 January 2016 to 5 January 2017 have been collected in Lecce, a coastal site of South-Eastern Italy (40.33°N, 18.11°E), and day-to-night changes of mass concentrations of both fine (PM2.5) and coarse (PM10-PM2.5) particles and corresponding chemical species have been assessed both in AW and in SS. The statistical analysis of local meteorological parameters and their correlations with PM2.5 and chemical species mass concentrations have indicated that the day-to-night changes of temperature (T) and wind speed (WS) likely affected the day-to-night changes of mass concentrations, because of the T and WS impact on the atmospheric turbulence and air particle dispersion. The daily evolution of the anthropogenic activities and the planetary-boundary-layer height likely contributed to the day-to-night changes of the particle chemical composition. The stagnant atmospheric conditions prevailing in SS all over the Mediterranean basin, which favoured the mixing and the accumulation of atmospheric particles from different pollution sources, likely contributed to the changes of the relationships between chemical species and meteorological parameters from AW to SS at daytime and nighttime. The analysis of the aerosol scattering coefficient, scattering Ångström exponent, and scattering Ångström exponent difference, retrieved from nephelometer measurements co-located in space and time with the PM samplings, has allowed characterizing the day-to-night change of the aerosol optical properties. The relationships between the particle chemical and optical properties allowed a good understanding of their changes both in AW and in SS. [ABSTRACT FROM AUTHOR]

Size-segregated (PM) aerosol samples have been systematically collected at Ny-Ålesund (Svalbard Islands, Norwegian Arctic) during the spring and summer 2010 and analysed for elemental composition (major and trace elements, rare earth elements) and stable lead isotope ratios (Pb/Pb, Pb/Pb). The analysis of the obtained dataset provided valuable information on the sources and long-range transport processes of atmospheric particulate and associated contaminants reaching the Arctic. In particular, a seasonal pattern was evident for Ba, Cd, Mn, Mo, Pb ( p value ≤0.05), showing a higher input of elements related to anthropogenic emissions in spring compared to summer. Pb isotope ratios clearly showed that the geographic source of the anthropogenic input is subjected to a seasonal shift with an increased contribution of air masses coming from the north Eurasia during spring, and air masses coming from North America during summer. This finding was further corroborated by back-trajectory analysis. Finally, the analysis of the rare earth elements revealed an uniform pattern, without significant differences between the two seasons. [ABSTRACT FROM AUTHOR]

Daily PM10 aerosol samples were collected at the Gruvebadet observatory, Ny-Ålesund (Svalbard Islands), during the spring-summer 2014 Italian Arctic Campaign. A total of 136 samples were analysed for ion (inorganic anions and cations, selected organic anions) composition aiming to evaluate the seasonal pattern of sulfate, as a key component of the Arctic haze. Ionic balances indicated a strong sulfate seasonality with mean spring concentration about 1.5 times higher than that measured in summer. The spring and summer aerosol was almost neutral, indicating that ammonia was the major neutralizing agent for atmospheric acidic species. The linear regression between sulfate from potential acidic sources (non-sea salt sulfate and non-crustal sulfate) and ammonium indicated that the mean sulfate/ammonium ratio was intermediate between semi-(NHHSO) and complete ((NH)SO) neutralization. Using sea-salt sodium as sea-spray marker, non-sea-salt calcium as crustal marker and methanesulfonic acid as biogenic marker, a detailed source apportionment for sulfate was carried out. The anthropogenic input (calculated as the differences between total sulfate and the sum of sea-salt, crustal and biogenic contributes) was found to be the most relevant contribution to the sulfate budget in the Ny-Ålesund aerosol in summer and, especially, in spring. In this last season, crustal, sea-salt, biogenic and anthropogenic sources accounted for 3.3, 12.0, 11.5 and 74.8 %, respectively. [ABSTRACT FROM AUTHOR]

The object of this study was to investigate the different modal behavior of ultrafine aerosol particles collected at the Gruvebadet observatory located in Ny-Ålesund (Svalbard Islands, 78°55′N, 11°56′E). Aerosol particle size distribution was measured in the size range from 10 to 470 nm typically from the beginning of spring to the beginning of fall during four (non-consecutive) years (2010, 2011, 2013 and 2014). The median concentration for the whole period taken into account was 214 particles cm, oscillating between the median maximum in July with a concentration of 257 particles cm and a median minimum in April with 197 particles cm. The median total number concentration did not present a well-defined seasonal behavior, as shown by contrast looking at the sub/modal number concentration, where distinct trends appeared in the predominant accumulation concentration recorded during April/May and the preponderant concentration of Aitken particles during the summer months. Lastly, the short side-by-side spring 2013 campaign performed at the Zeppelin observatory with a differential mobility particle sizer was characterized by an aerosol concentration mean steady difference between the two instruments of around 14 %, thereby supporting the reliability of the device located at Gruvebadet. [ABSTRACT FROM AUTHOR]

Aerosol samplings were performed both at ground level and at different heights upon the Ny-Ålesund polar station in June-July 2012 using a tethered balloon equipped with a sampling pump and meteorological sensors. The samples were analyzed by ion chromatography and scanning electron microscopy to characterize the sources and the evolution of the aerosol particles in the planetary boundary layer. The results show the main contribution of long-range over local/regional transported particles and sediments in the aerosols in the period of interest. Among the long-range sources, a main contribution was represented by Siberian local soils and regional wildfires which provided typical particles (metal oxides, calcareous grains), and ion species (nss-K, nss-SO ) to the aerosols. Among the local sources, a main contribution was represented by fly ash emitted by the cruise ships frequently landing around Ny-Ålesund during summer. Another aspect which results from aerosol particle characterization is the clear stratification of the planetary boundary layer upon Ny-Ålesund. This typical feature, which has been already documented in spring on the same site (Moroni et al. 2015), is quite effective also in summertime despite the higher potential of local dust production and the lower atmospheric stability characterizing this period. [ABSTRACT FROM AUTHOR]

Surface mass balance (SMB) distribution and its temporal and spatial variability is an essential input parameter in mass balance studies. Different methods were used, compared and integrated (stake farms, ice cores, snow radar, surface morphology, remote sensing) at eight sites along a transect from Terra Nova Bay (TNB) to Dome C (DC) (East Antarctica), to provide detailed information on the SMB. Spatial variability measurements show that the measured maximum snow accumulation (SA) in a 15 km area is well correlated to firn temperature. Wind-driven sublimation processes, controlled by the surface slope in the wind direction, have a huge impact (up to 85% of snow precipitation) on SMB and are significant in terms of past, present and future SMB evaluations. The snow redistribution process is local and has a strong impact on the annual variability of accumulation. The spatial variability of SMB at the kilometre scale is one order of magnitude higher than its temporal variability (20-30%) at the centennial time scale. This high spatial variability is due to wind-driven sublimation. Compared with our SMB calculations, previous compilations generally over-estimate SMB, up to 65% in some areas. [ABSTRACT FROM AUTHOR]