Trend analysis of aerosol particle physical properties at Villum Research Station, Northern Greenland

<p><strong>Introduction</strong></p><p>The Arctic region is particularly sensitive to global climate change, experiencing warming at twice the rate of the global average. Anthropogenic pollution (e.g. aerosols, black carbon, ozone, and greenhouse gases), which to a large extent originates from the mid-latitudes, is suspected to be partly responsible for this warming. Atmospheric aerosols can alter the planetary radiation balance directly through scattering and absorption and indirectly through modification of cloud properties. These interactions depend on aerosol physicochemical properties. The Arctic cryosphere and atmosphere has undergone significant changes in recent decades, accompanied by reductions in anthropogenic emissions, especially in Europe and North America. These changes have important ramifications for the ambient Arctic aerosol. Understanding the direction and magnitude of recent changes in the Arctic aerosol population is key to elucidating the implications for the changing Arctic, although this remains a scientific challenge. Here we report recent trends for aerosol particle physical properties, which will aid in this understanding of the changing Arctic.</p><p><strong>Measurement Site</strong><strong> & Methods</strong></p><p>All measurements were obtained at Villum Research Station (Villum, N 81<sup>o</sup>36’ W 16<sup>o</sup>39’ 24 m a.s.l) in northeastern Greenland. Particle number size distributions (PNSD) were measured using a Scanning Mobility Particle Sizer (SMPS) from 2010–2018.</p><p>We have utilized mode fitting on daily averaged PNSDs to characterize three distinct modes (Nucleation, Aitken, and Accumulation) along with geometric mean diameters (GMD) and number concentrations (PN) for each mode.</p><p>The trends in these parameters were identified and quantified using the Mann-Kendal test and Theil Sen slope on the 90<sup>th</sup> % confidence interval. Trends in different months were analyzed using daily modal parameters.</p><p><strong>Results</strong></p><p>Statistically significant (s.s.) decreasing trends were detected for the Nucleation and Aitken modes GMDs in the winter, spring, and summer, with the only s.s. increasing trends occurring in the autumn. The Accumulation mode GMD showed a s.s. decrease in the spring and s.s. increase in the summer. For the PN of each mode, large s.s. increasing trends were detected for Nucleation and Aitken mode PN in the spring and summer. The Accumulation mode PN showed a small s.s. increase in the summer and a large s.s. decrease in the autumn.</p><p>            These results show that ultrafine modes (Nucleation and Aitken) are decreasing in diameter while simultaneously increasing in number concentration. These trends are most likely related to changes in sea ice extent, as previous research has indicated a negative correlation between new particle formation and sea ice extent. The decrease in Accumulation mode GMD in spring (during the peak of the Arctic Haze) is possibly related to decreases in anthropogenic emissions, while the increase PN during summer could signal an increase in primary biogenic aerosol emissions from the ocean surface. The large decrease in Accumulation mode PN during autumn requires further investigation. </p><p>            This work will help confirm trends of other aerosol components observed at other High Arctic sites and can offer insight into the climatic implications (i.e., radiative balance and cloud properties) for a future Arctic climate.</p>

Сlimate-active aerosol components in the Siberian Arctic, by data from new-developed research aerosol station on island Bely

<p>Black carbon is a short - living climate forcer, it plays a significant role especially in the Arctic environment due to heating the atmosphere and changing the radiation balance while depositing on snow and ice. Analysis of black carbon (BC) in the Arctic atmosphere shows a contribution of anthropogenic combustion of fossil fuels and natural wildfires to the Arctic atmosphere chemistry as well as of the main characteristics of Arctic aerosol pollution. Presently, assessments of the environment and climate change in the Siberian Arctic are strongly complicated by an existing lack of knowledge about emission sources, quantity, and composition of the aerosol pollution defining the impacts on an Arctic ecosystem.</p><p>Research aerosol station is firstly installed on island Bely located in Kara sea, Siberian Arctic. It takes place on the pathway of air mass from the Northern Siberia region of high anthropogenic and gas flaring activity to the Arctic. Presently, assessments of the environment and climate change in this region are strongly complicated by an existing lack of knowledge about emission sources, quantity and composition of the aerosol pollution defining the impacts on an Arctic ecosystem. Aethalometer and aerosol sampling system is continuously operated on the aerosol station in order to analyze black carbon and chemical characteristics including ionic and elemental composition. Annual BC trend obtained from august 2019 to September 2020 shows the typical Arctic aerosol tendency of a seasonal variability, disturbed by episodes of large-scale emission transportation.</p><p>Unprecedented high BC is observed in September 2020 at the research aerosol station on the island Bely. The BC concentrations early in September were exceeded 20 times the arctic background. They are found to be even higher than the highest arctic haze concentrations observed in December 2019.   Monthly averaged black carbon concentration in September 2020 exceeded 3 times that one in previous summer months. Such strong event is a result of large-scale air mass transportation from Eurasian continent in the period of strong wildfires in western Siberia, namely in Krasnoyarsk Kray and Yakutia, where around one million hectares of forest were burned out in August 2020. </p><p>Basic researches of aerosol characteristics as a tracer of anthropogenic emissions are supported by Russian Fond for Basic Research, project №18-60084.</p><p>.</p>

Aerosol Investigation During the Arctic Haze Season of 2018: Optical and Microphysical Properties

In this work, optical and microphysical properties of Arctic aerosol as well as their radiative impact are investigated. Air-borne Lidar observations along with ground-based measurements are evaluated for the Arctic Haze season of 2018. Aerosol abundance as inferred from particle backscatter was typical for this period of the year, with nearly spherical and large particles. The inversion of microphysical properties yielded high Refractive Index (RI) together with low Single-Scattering Albedo (SSA), suggesting absorbing particles. A fitted lognormal volume distribution revealed a fine mode with effective radius (reff) of μm and a coarse mode with reff=0.75 μm. The total radiative balance on ground was positive (12 Wm-2).

Aerosol Investigation During the Arctic Haze Season of 2018: Optical and Hygroscopic Properties

In the beginning of March 2018, Lidar measurements were performed on Svalbard, Arctic Ocean, in order to analyse the optical and hygroscopic properties of Arctic aerosol. In this study, aerosol backscatter showed significant higher values in lower altitudes. The analysis of the Colour Ratio (CR) revealed smaller particles in lower altitudes, with larger particles appearing only above Investigation of the hygroscopic character was done by applying the growth parameter introduced by Gassó et al. (2000). It was found that the method of Zieger et.al. (2010) can be successfully extended to backscatter and CR data from Lidar measurements. Ice nucleation was examined in ice supersaturation conditions, with no ice cloud formation observed. This indicated that the role of Arctic aerosol as ice nuclei is still a poorly understood issue.

Emerging investigator series: influence of marine emissions and atmospheric processing on individual particle composition of summertime Arctic aerosol over the Bering Strait and Chukchi Sea

Composition of individual atmospheric particles reveals the influence of marine sources, terrestrial sources, and anthropogenic sources on atmospheric chemistry in the changing Alaskan Arctic.