Saharan dust episodes and giant quartz particles in Iceland

Abstract

<p>Saharan dust has an impact on the atmospheric environment and sedimentary units in distant regions. Although Iceland is located within one of the main atmospheric dust pathways moving towards the Arctic, no evidence of Saharan dust deposition has been provided to date for the region. Here we present the results of fourteen Saharan dust episodes, which were identified in Iceland between 2008 to 2020. Aerosol optical depth data of Terra MODIS, HYSPLIT backward trajectories and numerical simulations of Barcelona Supercomputing Center were used in this work to identify the dust episodes. <br>Grain size and shape of the Saharan mineral material deposited in Iceland during two severe deposition events were investigated in detail. Icelandic dust samples from the most active local dust sources were compared with samples of deposited mineral dust from these two severe Saharan dust events to determine their granulometric (complex grain size and shape parameters) and mineralogical characteristics. An automated static optical image analysis technique was applied to thousands of individual particles, and was completed by Raman spectroscopy to identify external quartz particles. <br>Saharan dust episodes were associated with enhanced meridional atmospheric flow patterns driven by unusual meandering jets. Strong southerly winds were able to carry large Saharan quartz particles (> 100 µm) towards Iceland. Our results confirm the atmospheric pathways of Saharan dust towards the Arctic, and identify new pathways of giant Saharan dust particles in the study region, including the first evidence of their deposition in Iceland as previously predicted by models.<br>The support of the National Research, Development, and Innovation Office (projects NKFIH KH130337 and K120620 (for G. Varga)), Czech Science Foundation (project No. 20-06168Y (for P. Dagsson-Waldhauserova)), and COST inDust Action are gratefully acknowledged.</p>