Vertical distribution of aerosols in dust storms during the Arctic winter

High Latitude Dust (HLD) contributes 5% to the global dust budget, but HLD measurements are sparse. 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 40 particles cm−3 during dust storms. A moderate dust storm with >250 particles cm−3 (2 km altitude) was captured on 10th January 2016 as a result of sediments suspended from glacial outburst flood Skaftahlaup in 2015. Similar 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. 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.
The instrument and the gondola were built by ENVEA and MeteoModem companies. The flights were conducted in cooperation with the Icelandic Meteorological Office and the Agricultural University of Iceland. The various copies of LOAC used in the campaigns were funded by the French program “VOLTAIRE Labex (Laboratoire d’Excellence ANR-10-LABX-100-01)”. The preparation of this manuscript was funded by the Icelandic Research Fund (Rannis) Grant No. 152248-051. We acknowledge the use of imagery from the NASA Worldview application (https://worldview.earthdata.nasa.gov), part of the NASA Earth Observing System Data and Information System (EOSDIS), as well as NASA CALIPSO application (Dr. Charles Trepte, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations, https://www-calipso.larc.nasa.gov). We thank Mark Francis Sixsmith for his proofreading of this work. RAX (photographer Ragnar Axelsson) captured our field work in the greatest detail and we are thankful to use his photograph in this manuscript.