Abstract
Abstract. Understanding aerosol–cloud–climate interactions in the Arctic is key to predicting the climate in this rapidly changing region. Whilst many studies have focused on submicrometer aerosol (diameter less than 1 µm), relatively little is known about the supermicrometer aerosol (diameter above 1 µm). Here, we present a cluster analysis of multiyear (2015–2019) aerodynamic volume size distributions, with diameter ranging from 0.5 to 20 µm, measured continuously at the Gruvebadet Observatory in the Svalbard archipelago. Together with aerosol chemical composition data from several online and offline measurements, we apportioned the occurrence of the coarse-mode aerosols during the study period (mainly from March to October) to anthropogenic (two sources, 27 %) and natural (three sources, 73 %) origins. Specifically, two clusters are related to Arctic haze with high levels of black carbon, sulfate and accumulation mode (0.1–1 µm) aerosol. The first cluster (9 %) is attributed to ammonium sulfate-rich Arctic haze particles, whereas the second one (18 %) is attributed to larger-mode aerosol mixed with sea salt. The three natural aerosol clusters were open-ocean sea spray aerosol (34 %), mineral dust (7 %) and an unidentified source of sea spray-related aerosol (32 %). The results suggest that sea-spray-related aerosol in polar regions may be more complex than previously thought due to short- and long-distance origins and mixtures with Arctic haze, biogenic and likely blowing snow aerosols. Studying supermicrometer natural aerosol in the Arctic is imperative for understanding the impacts of changing natural processes on Arctic aerosol.
Highlights
The Arctic is one of the most sensitive regions of the world, and the Arctic environment is experiencing tremendous changes at a much faster pace than lower latitudes
For the seven-cluster solution, we observed an obvious increase in the Dunn Index (DI) value but a decrease in the silhouette width (SW) value compared to those from the five-cluster solution, suggesting that some of the clusters in the seven-cluster solution tend to be similar to neighboring clusters
Our results provide insights into supermicrometer aerosol properties and their potential sources around at an Arctic site in Svalbard, sea spray aerosol, MSA-containing biogenic aerosol and mineral dust
Summary
The Arctic is one of the most sensitive regions of the world, and the Arctic environment is experiencing tremendous changes at a much faster pace than lower latitudes The rising temperature, sea ice melt and local air pollutant emissions (Schmale et al, 2018) in the Arctic all exert a broad range of impacts on natural and anthropogenic processes, thereby changing Arctic aerosol properties and radiative forcing and cloud formation (Abbatt et al, 2019; Willis et al, 2018). A better knowledge of Arctic aerosol is an essential requisite for narrowing the uncertainty in assessing the impacts of aerosols on cloud formation and climate change (Schmale et al, 2021). It is known that aerosol–cloud–climate interactions depend upon aerosol properties, such as concentration, size distribution and chemical composition. The size distribution of aerosols is important as size dictates many of the direct and indirect climate forcing properties of aerosols, as well as indicating their sources and atmospheric lifetimes
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