Arctic Aerosol Research Articles

Biomass Burning is an Important Source of Organic Aerosols in Interior Alaska

AbstractBiomass burning (BB) affects air quality, the global cycling of carbon, climate, and human health. Intensive BB activities occur throughout the year due to wildfires and domestic wood burning in Fairbanks. We collected total suspended particle samples from the air in Fairbanks from June 2008 to June 2009. Here, we report seasonal variations in the molecular composition of organic aerosols and its BB contributions in Fairbanks. Levoglucosan is the dominant BB tracer (annual mean 67 ± 77 ng m−3), showing a winter maximum (145 ± 47 ng m−3) and spring minimum (12 ± 12 ng m−3). Levoglucosan showed significant correlations (p < 0.001) with organic carbon (OC), water‐soluble organic carbon (WSOC), and PM2.5, indicating a significant contribution of BB to hazes in Fairbanks. However, no correlation exists between levoglucosan and non‐sea salt potassium (nss‐K+), which has been proposed as a BB tracer. We hypothesize that nss‐K+ is removed by deposition on the inner surfaces of woodstove chimneys. Levoglucosan contributes 3.6% to OC and 6.3% to WSOC in winter, indicating that BB significantly affects carbonaceous aerosols in central Alaska. Moreover, positive matrix factorization analysis demonstrates that BB is an important source (47.5%) of Fairbanks year‐round aerosols. We conclude that domestic wood burning is an important source of atmospheric particles that impact the air quality of Fairbanks, especially in winter. We presumed that Fairbanks BB products might be transported to the remote Arctic, potentially affecting the chemical composition of Arctic aerosols. These findings will be useful to better understand the seasonal influence of BB on the Arctic and subarctic aerosols.

A long-term study of cloud residuals from low-level Arctic clouds

Abstract. To constrain uncertainties in radiative forcings associated with aerosol–cloud interactions, improved understanding of Arctic cloud formation is required, yet long-term measurements of the relevant cloud and aerosol properties remain sparse. We present the first long-term study of cloud residuals, i.e. particles that were involved in cloud formation and cloud processes, in Arctic low-level clouds measured at Zeppelin Observatory, Svalbard. To continuously sample cloud droplets and ice crystals and separate them from non-activated aerosol, a ground-based counter-flow virtual impactor inlet system (GCVI) was used. A detailed evaluation of the GCVI measurements, using concurrent cloud particle size distributions, meteorological parameters, and aerosol measurements, is presented for both warm and cold clouds, and the potential contribution of sampling artefacts is discussed in detail. We find an excellent agreement of the GCVI sampling efficiency of liquid clouds using two independent approaches. The 2-year data set of cloud residual size distributions and number concentrations reveals that the cloud residuals follow the typical seasonal cycle of Arctic aerosol, with a maximum concentration in spring and summer and a minimum concentration in the late autumn and winter months. We observed average activation diameters in the range of 58–78 nm for updraught velocities below 1 m s−1. A cluster analysis also revealed cloud residual size distributions that were dominated by Aitken mode particles down to around 20–30 nm. During the winter months, some of these small particles may be the result of ice, snow, or ice crystal shattering artefacts in the GCVI inlet; however, cloud residuals down to 20 nm in size were also observed during conditions when artefacts are less likely.

A Year-Round Measurement of Water-Soluble Trace and Rare Earth Elements in Arctic Aerosol: Possible Inorganic Tracers of Specific Events

This study presents the year-round variability of the water-soluble fraction of trace elements (wsTE) and rare earth elements (wsREE) among size segregated airborne particulate matter samples collected at Ny-Ålesund in the Svalbard Archipelago from 26 February 2018 to 26 February 2019. Six different aerosol dimensional fractions were collected using a multi-stage Andersen impactor to better understand local and global circulation with the aim of disentangling the source of inorganic tracers from specific natural or anthropogenic sources. The wsTE and wsREE content, especially in the finest fractions in remote areas, is primarily related to long-range transport and it gives valuable information on (1) the global circulation, (2) the natural sources and (3) the contribution of human activities to aerosol composition. A Factor Analysis was applied to the dataset, including levoglucosan and methanesulfonic acid (MSA), to assess the possibility of using certain inorganic tracers as indicators of specific transport events or circulation regimes. We also investigate back-trajectories to determine potential source areas.

Arctic aerosols and the ‘Divergence Problem’ in dendroclimatology

Considering the importance and complexity of natural (e.g., volcanic eruptions and wildfires) and anthropogenic (e.g., mining, oil and shipping industries) aerosol emissions to Arctic warming is particularly timely given the recent temperature extremes recorded at high-northern latitudes (Cohen et al., 2020; Overland and Wang, 2021). Despite our knowledge about the observed and modelled climatic effects of rising Arctic aerosol concentrations (Schmale et al., 2021), which may exhibit regional and seasonal differences and call for diverse research priorities from local to circumpolar scales, we feel that the ecological consequences of an aerosol-induced reduction in surface irradiance (i.e., Arctic Dimming) justify more thorough tree-ring investigations in the future. We argue that this is particularly true if the goal is to enhance our understanding of all aerosol generating processes that impact terrestrial vegetation and its ability to assimilate carbon dioxide from the atmosphere.

Assessing the vertical structure of Arctic aerosols using balloon-borne measurements

Abstract. The rapidly warming Arctic is sensitive to perturbations in the surface energy budget, which can be caused by clouds and aerosols. However, the interactions between clouds and aerosols are poorly quantified in the Arctic, in part due to (1) limited observations of vertical structure of aerosols relative to clouds and (2) ground-based observations often being inadequate for assessing aerosol impacts on cloud formation in the characteristically stratified Arctic atmosphere. Here, we present a novel evaluation of Arctic aerosol vertical distributions using almost 3 years' worth of tethered balloon system (TBS) measurements spanning multiple seasons. The TBS was deployed at the U.S. Department of Energy Atmospheric Radiation Measurement Program's facility at Oliktok Point, Alaska. Aerosols were examined in tandem with atmospheric stability and ground-based remote sensing of cloud macrophysical properties to specifically address the representativeness of near-surface aerosols to those at cloud base. Based on a statistical analysis of the TBS profiles, ground-based aerosol number concentrations were unequal to those at cloud base 86 % of the time. Intermittent aerosol layers were observed 63 % of the time due to poorly mixed below-cloud environments, mostly found in the spring, causing a decoupling of the surface from the cloud layer. A uniform distribution of aerosol below cloud was observed only 14 % of the time due to a well-mixed below-cloud environment, mostly during the fall. The equivalent potential temperature profiles of the below-cloud environment reflected the aerosol profile 89 % of the time, whereby a mixed or stratified below-cloud environment was observed during a uniform or layered aerosol profile, respectively. In general, a combination of aerosol sources, thermodynamic structure, and wet removal processes from clouds and precipitation likely played a key role in establishing observed aerosol vertical structures. Results such as these could be used to improve future parameterizations of aerosols and their impacts on Arctic cloud formation and radiative properties.

In situ optical and microphysical properties of tropospheric aerosols in the Canadian High Arctic from 2016 to 2019

Since aerosols are an integral part of the Arctic climate system, understanding aerosol radiative properties and the relation of these properties to each other is important for constraining aerosol radiative forcing effects in this remote region where measurements are sparse. In situ measurements of aerosol size distribution, aerosol light scattering and absorption were taken near Eureka (80.05oN, 86.42oW), on Ellesmere Island, in the Canadian High Arctic over three consecutive years to provide insights into radiative properties of Arctic aerosols.During periods of Arctic haze, we find that the single scattering albedo (SSA) at 405 nm is generally higher and more stable than that determined at 870 nm, with values ranging between 0.90–0.99 and 0.79–0.97, respectively. Events with elevated absorption coefficients (Babs) exhibit generally an absorption Ångström exponent (AAE) of around 1 suggesting that black carbon (BC) is the dominant absorbing aerosol for the measurement period. AAE values close to 2 occurring with scattering Ångström exponent (SAE) values near 0 and SAE values below 0 occasionally observed in December indicate a potential contribution from mineral dust aerosols in late fall and early winter. The apparent real and imaginary parts of the complex refractive index at 405 nm have been found to range between 1.6–1.9 and 0.002–0.02, respectively. The low imaginary component indicates very weak intrinsic absorption compared to BC-rich aerosols.Systematic variabilities between different aerosol optical and microphysical properties depend strongly on the given wavelength. SSA at 405 nm shows a strong inverse dependence with Babs, because Babs correlates positively with the imaginary component of the refractive index. On the other hand, SSA at 870 nm correlates with scattering coefficient (Bsca) and not with Babs due to a greater sensitivity to the ambient particle size distribution for 870 nm scattering. Smaller particles with higher SAE that are prevalent during less polluted periods only weakly scatter at 870 nm leading to lower SSA when Bsca is also low.Lastly, FLEXPART back-trajectories show that lower aerosol SSA and higher Babs correspond to air masses which are more influenced by Eurasian and Alaskan regions, including regions known to have important BC emissions. This work emphasizes the important variability in Arctic aerosol optical properties during winter and spring, which is likely due to changes in source regions.

Aerosols in current and future Arctic climate

Mechanisms of Arctic amplification and Arctic climate change are difficult to pinpoint, and current climate models do not represent the complex local processes and feedbacks at play, in particular for aerosol–climate interactions. This Perspective highlights the role of aerosols in contemporary Arctic climate change and stresses that the Arctic natural aerosol baseline is changing fast and its regional characteristics are very diverse. We argue that to improve understanding of present day and future Arctic, more detailed knowledge is needed on natural Arctic aerosol emissions, their evolution and transport, and the effects on cloud microphysics. In particular, observation and modelling work should focus on the sensitivity of aerosol–climate interactions to the rapidly evolving base state of the Arctic. Aerosol–climate interactions are important in the Arctic, but they exhibit large spatiotemporal variability. This Perspective argues for community-driven model and observational improvement, emphasizing the need to understand natural aerosol processes and quantify how their baseline is changing.

Insights into the molecular composition of semi-volatile aerosols in the summertime central Arctic Ocean using FIGAERO-CIMS.

The remote central Arctic during summertime has a pristine atmosphere with very low aerosol particle concentrations. As the region becomes increasingly ice-free during summer, enhanced ocean-atmosphere fluxes of aerosol particles and precursor gases may therefore have impacts on the climate. However, large knowledge gaps remain regarding the sources and physicochemical properties of aerosols in this region. Here, we present insights into the molecular composition of semi-volatile aerosol components collected in September 2018 during the MOCCHA (Microbiology-Ocean-Cloud-Coupling in the High Arctic) campaign as part of the Arctic Ocean 2018 expedition with the Swedish Icebreaker Oden. Analysis was performed offline in the laboratory using an iodide High Resolution Time-of-Flight Chemical Ionization Mass Spectrometer with a Filter Inlet for Gases and AEROsols (FIGAERO-HRToF-CIMS). Our analysis revealed significant signal from organic and sulfur-containing compounds, indicative of marine aerosol sources, with a wide range of carbon numbers and O : C ratios. Several of the sulfur-containing compounds are oxidation products of dimethyl sulfide (DMS), a gas released by phytoplankton and ice algae. Comparison of the time series of particulate and gas-phase DMS oxidation products did not reveal a significant correlation, indicative of the different lifetimes of precursor and oxidation products in the different phases. This is the first time the FIGAERO-HRToF-CIMS was used to investigate the composition of aerosols in the central Arctic. The detailed information on the molecular composition of Arctic aerosols presented here can be used for the assessment of aerosol solubility and volatility, which is relevant for understanding aerosol–cloud interactions.

Studies on Arctic aerosols and clouds during the ArCS project

Aerosols and clouds play important roles in the Arctic climate. Conversely, aerosol emissions and cloud formation are affected by changes in the Arctic climate. This paper reviews studies of aerosols and clouds performed during the Arctic Challenge for Sustainability (ArCS) project carried out by the National Institute of Polar Research (NIPR) in Japan and collaborating institutions. The ArCS project included intensive studies of black carbon aerosols (BC). We installed Continuous Soot Monitoring System (COSMOS) instruments to measure atmospheric BC at four locations in the Arctic, establishing the Arctic BC COSMOS Measurement Network (ABCM-net). We also measured BC concentrations in snowpack in extensive areas of the Arctic and showed that previous studies have greatly overestimated BC in snowpack. We developed and improved new aerosol models that achieved better agreements with measurements of BC in the Arctic atmosphere, snowpack, and falling snow. We made new estimates of radiative forcing of BC in the Arctic atmosphere and snow/ice surfaces that lower their albedo. In addition to these researches on BC, we made accurate measurements of ice nucleating particles (INPs) at Ny-Ålesund, Svalbard, showing that their concentrations increased in summer as a result of dust particle emissions from glacial outwash sediments. This high ice nucleating ability was likely due to the presence of organic substances mixed with the dust particles. We also made continuous cloud radar measurements and the first continuous in-situ measurements of cloud microphysical properties in the Arctic at Ny-Ålesund. Results from these cloud measurements and their relationship with aerosols are described.

Year-round measurements of size-segregated low molecular weight organic acids in Arctic aerosol

Organic acids in aerosols Earth's atmosphere are ubiquitous and they have been extensively studied across urban, rural and polar environments. However, little is known about their properties, transport, source and seasonal variations in the Svalbard Archipelago. Here, we present the annual trend of organic acids in the aerosol collected at Ny-Ålesund and consider their size-distributions to infer their possible sources and relative contributions. A series of carboxylic acids were detected with a predominance of C2-oxalic acid. Pinic acid and cis-pinonic acid were studied in order to better understand the oxidative and gas-to-particle processes occurred in the Arctic atmosphere. Since the water-soluble organic fraction is mainly composed by organic acids and ions, we investigated how the seasonal variation leads to different atmospheric transport mechanisms, focusing on the chemical variations between the polar night and boreal summer. Using major ions, levoglucosan and MSA, the Positive Matrix Factorization (PMF) identified five different possible sources: a) sea spray; b) marine primary production; c) biomass burning; d) sea ice related process and e) secondary products.

Application of the shipborne remote sensing supersite OCEANET for profiling of Arctic aerosols and clouds during <i>Polarstern</i> cruise PS106

Abstract. From 25 May to 21 July 2017, the research vessel Polarstern performed the cruise PS106 to the high Arctic in the region north and northeast of Svalbard. The mobile remote-sensing platform OCEANET was deployed aboard Polarstern. Within a single container, OCEANET houses state-of-the-art remote-sensing equipment, including a multiwavelength Raman polarization lidar PollyXT and a 14-channel microwave radiometer HATPRO (Humidity And Temperature PROfiler). For the cruise PS106, the measurements were supplemented by a motion-stabilized 35 GHz cloud radar Mira-35. This paper describes the treatment of technical challenges which were immanent during the deployment of OCEANET in the high Arctic. This includes the description of the motion stabilization of the cloud radar Mira-35 to ensure vertical-pointing observations aboard the moving Polarstern as well as the applied correction of the vessels heave rate to provide valid Doppler velocities. The correction ensured a leveling accuracy of ±0.5∘ during transits through the ice and an ice floe camp. The applied heave correction reduced the signal induced by the vertical movement of the cloud radar in the PSD of the Doppler velocity by a factor of 15. Low-level clouds, in addition, frequently prevented a continuous analysis of cloud conditions from synergies of lidar and radar within Cloudnet, because the technically determined lowest detection height of Mira-35 was 165 m above sea level. To overcome this obstacle, an approach for identification of the cloud presence solely based on data from the near-field receiver of PollyXT at heights from 50 m and 165 m above sea level is presented. We found low-level stratus clouds, which were below the lowest detection range of most automatic ground-based remote-sensing instruments during 25 % of the observation time. We present case studies of aerosol and cloud studies to introduce the capabilities of the data set. In addition, new approaches for ice crystal effective radius and eddy dissipation rates from cloud radar measurements and the retrieval of aerosol optical and microphysical properties from the observations of PollyXT are introduced.

Spatiotemporal Variability in Modeled Bottom Ice and Sea Surface Dimethylsulfide Concentrations and Fluxes in the Arctic During 1979–2015

Field observations suggest that oceanic emissions of dimethylsulfide (DMS) may play a dominant role in the production of Arctic aerosols and clouds and therefore modulate the surface irradiance, during spring and summer. DMS is produced not only in the water column but also in various sea ice habitats. The ongoing recession of Arctic sea ice is expected to enhance DMS emissions, but the magnitude of this increase is highly uncertain. Here we investigate the spatiotemporal variability in bottom ice and sea surface DMS concentrations and fluxes using a regional sea ice‐ocean physical‐biogeochemical model. Model results indicate that the observed accelerated decline of Arctic sea ice extent since the beginning of the 21st century is associated with upward trends in May–August pan‐Arctic‐averaged sea surface DMS concentration and sea‐to‐air DMS flux. On the other hand, strong interannual variability and statistically insignificant trends are found for bottom ice DMS concentration and ice‐to‐sea DMS flux, owing to the counteracting effects of the shrinking horizontal extent and the vertical thinning of sea ice on ice algal production. The pan‐Arctic DMS climatology products based on model simulation and satellite algorithms provide dynamically based spatial details that are absent in the in situ measurement‐based climatology due to limited spatiotemporal data coverage and inevitable extrapolation bias. Lastly, model results indicate that the bottom ice DMS and its precursor dimethylsulfoniopropionate production can be the only local source of oceanic DMS emissions into the atmosphere during May prior to pelagic blooms, suggesting that it may be a key component of the biological control on Arctic climate at that time.

High Sensitivity of Arctic Black Carbon Radiative Effects to Subgrid Vertical Velocity in Aerosol Activation

AbstractThe representation of aerosol activation into cloud droplets in climate models is important for accurate understanding of aerosol radiative impacts on the Arctic climate, but it remains highly uncertain. Here we show that the uncertainty range of subgrid vertical velocity (SVV) and maximum supersaturation (SSmax) in aerosol activation produces fourfold to fivefold differences in the direct radiative effect of black carbon (BC) in the Arctic (0.091–0.40 W m−2) because SVV and SSmax determine the activated fraction and wet removal efficiency of aerosols. Aerosols are particularly sensitive to SVV in remote regions but not near their sources because many aerosols near sources are not yet influenced by wet removal processes. Our results demonstrate that SVV treatment is a major source of uncertainty in Arctic aerosol simulations and may be key for reducing the large discrepancies among global models in estimates of BC and its radiative effects in the Arctic.

New insights on metals in the Arctic aerosol in a climate changing world

Ship traffic, population, infrastructure development, and mining activities are expected to increase in the Arctic due to its rising temperatures. This is expected to produce a major impact on aerosol composition. Metals contained in atmospheric particles are powerful markers and can be extremely helpful to gain insights on the different aerosol sources. This work aims at studying the sources of metals in the Arctic aerosol sampled at the Thule High Arctic Atmospheric Observatory (THAAO; Greenland, 76.5°N 68.8°W).Due to the particular composition of Greenlandic soils and to properties of other sources, it was possible to find several signatures of natural and anthropogenic aerosols transported from local and long-range regions.Arctic haze (AH) at Thule builds up on long-range transported aerosol mainly from Canada and Nord America. From a chemical standpoint, this aerosol is characterized by a high concentration of sulfate, Pb, As and Cd and by a La/Ce ratio larger than 1. The Ti/Al and Fe/Al ratios in the AH aerosol are lower (Ti/Al = 0.04 w/w; Fe/Al = 0.79 w/w) than for local aerosol (Ti/Al = 0.07 w/w; Fe/Al = 0.89 w/w).Conversely, aerosol arising from coastal areas of South-West Greenland is characterized by a high concentration of V, Ni, and Cr. These metals, generally considered anthropogenic, arise here mainly from natural crustal sources. In some summer samples, however, the V/Ni ratio becomes larger than 3. In particular, cases displaying this characteristic ratio, as also shown by backward trajectories, are associated with sporadic transport to Thule of ship aerosol from ships passing through Baffin Bay and arriving to Thule during summer.Although further measurements are necessary to confirm the discussed results, the analysis carried out in this work on a large number of metals sampled in coastal Greenland aerosol is unprecedented.

Climatological‐Scale Analysis of Intensive and Semi‐intensive Aerosol Parameters Derived From AERONET Retrievals Over the Arctic

AbstractWe investigated the climatological‐scale, monthly binned, seasonal variation of AERONET/Dubovik retrievals across six stations in the North American and European Arctic (multiyear sampling periods ranging from 8 to 17 years). A robust, spring‐to‐summer (StoS) increase in the radius of the peak of the fine mode (FM) component of the particle size distribution (PSD) was observed for five of the six stations. The FM aerosol optical depth (AOD) and the FM effective radius at the individual stations showed, respectively, a negligible to moderate StoS decrease and a significant increase. This was interpreted as a trade‐off between the waning influence of smaller FM Arctic haze aerosols and the increasing influence of large FM smoke particles. A springtime, pan‐Arctic PSD peak in the 1.3 μm coarse mode (CM) bin was attributed to Asian dust. It was suggested that the increase in amplitude of a second (4–7 μm) CM peak from July to August at the low‐elevation coastal sites was influenced by wind‐induced sea salt. The CM AOD went through a StoS decrease attributed to the decreasing amplitude of the 1.3 μm peak. A significant StoS CM effective radius increase was ascribed to the decreasing influence of the 1.3 μm peak. StoS FM fraction increases were largely due to the decrease of the CM AOD (decreasing influence of springtime Asian dust). This extensive and intensive climatology of remotely sensed, bimodal properties will, we believe, provide an important reference for future measurements and modeling of Arctic aerosols.

Repeatability of INP activation from the vapor

Laboratory generated aerosols and aerosol sampled in a field campaign were studied to assess the repeatability of heterogeneous ice activation processes and verify if the ice nuclei particles maintained their nucleating capability. Experiments were performed using a filter technique, i.e. aerosol particles were sampled on black-gridded cellulose nitrate membrane filters and assessed for ice nucleating particles in a dynamic filter-processing chamber at our ISAC-CNR laboratory. The laboratory investigations used Arizona Test Dust (ATD) generated by nebulizing a suspension of ATD. After nebulization, the wet aerosol in the carrier gas was dried and then sampled on a filter. Aerosol field sampling (size range PM1 and PM10) was carried out in the Arctic (Ny-Ålesund, Svalbard) from 12 to 23 April 2019. The activation processes were repeated twice for each filter at temperatures of −22 °C and −18 °C. For aerosol, ATD runs were performed only in conditions of supersaturation (saturation ratio Sw = 1.02), while for the Arctic aerosol, conditions below saturation were also considered (Sw = 0.96). The experiments showed that approximately 40% of the ATD particles maintain their initial nucleating efficiency, both at T = −22 °C and − 18 °C, and at Sw = 1.02, i.e. in the condensation freezing mode. The percentage of repeatability was higher for ATD with respect to the Artic-sampled aerosol processed in the condensation mode. This may depend on greater particle morphology variation of the mixed organic-inorganic aerosol due to the hydration and dehydration cycle.

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.

The Arctic is rapidly transforming due to sea ice loss, increasing shipping activity, and oil and gas development. Associated marine and combustion emissions influence atmospheric aerosol composition, impacting complex aerosol-cloud-climate feedbacks. To improve understanding of the sources and processes determining Arctic aerosol composition, atmospheric particles were collected aboard the Korean icebreaker R/V Araon cruising within the Bering Strait and Chukchi Sea during August 2016. Offline analyses of individual particles by microspectroscopic techniques, including scanning electron microscopy with energy dispersive X-ray spectroscopy and atomic force microscopy with infrared spectroscopy, provided information on particle size, morphology, and chemical composition. The most commonly observed particle types were sea spray aerosol (SSA), comprising ∼60-90%, by number, of supermicron particles, and organic aerosol (OA), comprising ∼50-90%, by number, of submicron particles. Sulfate and nitrate were internally mixed within both SSA and OA particles, consistent with particle multiphase reactions during atmospheric transport. Within the Bering Strait, SSA and OA particles were more aged, with greater number fractions of particles containing sulfate and/or nitrate, compared to particles collected over the Chukchi Sea. This is indicative of greater pollution influence within the Bering Strait from coastal and inland sources, while the Chukchi Sea is primarily influenced by marine sources.

Aerosol carbonaceous, elemental and ionic composition variability and origin at the Siberian High Arctic, Cape Baranova

Aerosol particles are major short-lived climate forcers, because of their ability to interact with incoming solar radiation. Therefore, addressing mean levels and sources of Arctic aerosols is of high importance in the battle against climate change, due to the Arctic amplification. In the Eastern Arctic, from Finland to Alaska, only one monitoring station exists (HMO Tiksi) and the levels of the Arctic aerosols are usually recorded by sporadic campaigns, while other stations exist in Canada, Finland and Europe. From April 2015 to December 2016, the research station "Ice Base Cape Baranova" (79°16.82'N, 101°37.05'E), located on the Bolshevik island was established in the Siberian high Arctic. Samples were analyzed for equivalent Black Carbon (eBC), Organic Carbon (OC), Elemental Carbon (EC), water-soluble ions, and elements. To identify the spatial origin of the sources, the Potential Source Contributions Function (PSCF) was used in combination with FLEXPART emission sensitivities. OC is the most dominant PM compound in the Ice Cape Baranova station and mostly originates from gas flaring and other industrial regions at lower latitudes, as well as from biomass burning during summertime. Sulfate concentrations were affected by anthropogenic sources in the cold seasons and by natural sources in the warm ones showing distinct seasonal patterns. K+ and Mg2+ originate from sea-salt in winter and from forest fires in summer. The interannual variability of eBC was in good agreement with the general Arctic seasonal trends and was mainly affected by gas flaring, low latitude industrial sources and from biomass burning emissions. Cl− depletion was very low, while Na+ and Cl− originated from the locally formed sea spray.

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).