Vertical distribution of aerosols in dust storms during the Arctic winter

Abstract

<p>High Latitude Dust (HLD) contributes 5% to the global dust budget, but HLD measurements are sparse. Iceland has the largest area of volcaniclastic sandy desert on Earth where dust is originating from volcanic, but also glaciogenic sediments. Total Icelandic desert areas cover 44,000 km<sup>2</sup> which makes Iceland the largest Arctic as well as European desert. Icelandic volcanic dust can be transported distances > 1700 km towards the Arctic and deposited on snow, ice and sea ice. It is estimated that about 7% of Icelandic dust can reach the high Arctic (N>80°). It is known that about 50% of Icelandic dust storms occurred during winter or subzero temperatures in the southern part of Iceland. The vertical distributions of dust aerosol in high atmospheric profiles during these winter storms and long-range transport of dust during polar vortex condition were unknown.</p><p>Dust observations from Iceland provide dust aerosol distributions during the Arctic winter for the first time, profiling dust storms as well as clean air conditions. Five winter dust storms were captured during harsh conditions.  Mean number concentrations during the non-dust flights were < 5 particles cm<sup>-3 </sup>for the particles 0.2-100 µm in diameter and > 40 particles cm<sup>-3</sup> during dust storms. A moderate dust storm with > 250 particles cm<sup>-3</sup> (2 km altitude) was captured on 10<sup>th</sup> January 2016 as a result of sediments suspended from glacial outburst flood Skaftahlaup in 2015. Similar particle number concentrations were reported previously in the Saharan air layer. Detected particle sizes were up to 20 µm close to the surface, up to 10 µm at 900 m altitude, up to 5 µm at 5 km altitude, and submicron at altitudes > 6 km.</p><p>Dust sources in the Arctic are active during the winter and produce large amounts of particulate matter dispersed over long distances and high altitudes. HLD contributes to Arctic air pollution and has the potential to influence ice nucleation in mixed-phase clouds and Arctic amplification.</p><p> </p><p>Reference:</p><p>Dagsson-Waldhauserova, P., Renard, J.-B., Olafsson, H., Vignelles, D., Berthet, G., Verdier, N., Duverger, V., 2019. Vertical distribution of aerosols in dust storms during the Arctic winter. <strong>Scientific Reports </strong>6, 1-11.</p>

Iceland is an episodic source of atmospheric ice-nucleating particles relevant for mixed-phase clouds

“…These volcanic soils in "sandy deserts" across Iceland are susceptible to aerosolization through the action of wind, which produces frequent dust events (9,(14)(15)(16)(17)24). Furthermore, Icelandic dust can be transported to locations thousands of kilometers away from the original source (25) and can reach altitudes and latitudes where mixed-phase cloud formation can occur (16,26).…”

Newly identified climatically and environmentally significant high-latitude dust sources

“…In our collection, 13 new sources in Iceland were included (Table S2) compared to previous sources, in which eight Icelandic dust hotspots were identified (Arnalds et al, 2016). Sandkluftavatn, Kleifarvatn, Skafta jökulhlaup deposits, and other areas have also been found to produce large amounts of dust (Dagsson-Waldhauserová et al, 2019). In recent years, increased dust activity has been reported in Flosaskard and Vonaskard (Gunnarsson et al, 2021).…”

Newly identified climatically and environmentally significant high latitude dust sources

“…Previously, eight dust hot spots have been identified in Iceland (Arnalds et al, 2016). Additionally, Sandkluftavatn, Kleifarvatn, Skafta jökulhlaup deposits and other areas have been lately found to produce large amounts of dust (Dagsson-Waldhauserova et al, 2019). In recent years, increased dust activity has been reported also from Flosaskard and Vonaskard (Gunnarsson et al, 2020).…”