Study of Chemical and Optical Properties of Biomass Burning Aerosols during Long-Range Transport Events toward the Arctic in Summer 2017

Abstract

Biomass burning related aerosol episodes are becoming a serious threat to the radiative balance of the Arctic region. Since early July 2017 intense wildfires were recorded between August and September in Canada and Greenland, covering an area up to 4674 km2 in size. This paper describes the impact of these biomass burning (BB) events measured over Svalbard, using an ensemble of ground-based, columnar, and vertically-resolved techniques. BB influenced the aerosol chemistry via nitrates and oxalates, which exhibited an increase in their concentrations in all of size fractions, indicating the BB origin of particles. The absorption coefficient data (530 nm) at ground reached values up to 0.6 Mm–1, highlighting the impact of these BB events when compared to average Arctic background values, which do not exceed 0.05 Mm–1. The absorption behavior is fundamental as implies a subsequent atmospheric heating. At the same time, the AERONET Aerosol Optical Depth (AOD) data showed high values at stations located close to or in Canada (AOD over 2.0). Similarly, increased values of AODs were then observed in Svalbard, e.g., in Hornsund (daily average AODs exceeded 0.14 and reached hourly values up to 0.5). Elevated values of AODs were then registered in Sodankylä and Andenes (daily average AODs exceeding 0.150) a few days after the Svalbard observation of the event highlighting the BB columnar magnitude, which is crucial for the radiative impact. All the reported data suggest to rank the summer 2017 plume of aerosols as one of the biggest atmosphere related environmental problems over Svalbard region in last 10 years.

On the nightglow polarisation for space weather exploration

“…That is indeed true since the aerosols move permanently in any direction, changing randomly the polarisation angle, and thus providing a strong argument against their implication. Finally, their presence lasts for hours and can hardly explain our rapid variations (Zielinski et al, 2020).…”

“…Unfortunately, we could only find very sparse times with coordinated operation, not enough to conclude about this effect. The operator of the Lidar, Christoph Ritter (personal communication), mentioned to us: "In total the aerosol load in the Arctic is quite low and it is clearer in autumns and more polluted in spring (Zielinski et al, 2020). Hence if aerosol were the reason I would expect that you see in spring on more days more erratic polarisation than in autumn."…”

Investigation on the Sources and Impact of Trace Elements in the Annual Snowpack and the Firn in the Hansbreen (Southwest Spitsbergen)

“…However, the long-range transport of atmospheric dust and wildfire emissions from Eurasia can significantly impact the elemental composition of the annual snowpack (Moroni et al, 2016;Feltracco et al, 2020). A recent study investigating the lead isotope composition of aerosol samples suggests a predominant contribution of air masses from North Eurasia during spring, and the main influence during summer coming from North America (Barbaro et al, 2016;Zielinski et al, 2020). Furthermore, the anticipated shortening of the snow season, combined with glacier retreat, will increase the time and extent of soil exposure locally, thus likely enhancing the impact of dust on snowpack composition.…”

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