Iceland as a model for high-latitude dust sources – a combined experimental and modeling approach for characterization of dust emission and transport processes (HiLDA)

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Mineral dust is undoubtedly with regard to climate impact and biosphere interaction one of the most important aerosol types in the atmosphere. While the largest amount of dust emission is linked to the warm deserts, recently cold deserts get into focus. High-latitude dust (HLD), other than non-HLD, is e.g. involved in changing nearby glacier albedo, enhancing or modifying high-latitude ocean productivity, transporting organic pollutants or modifying arctic clouds by providing ice-nucleating particles. As major transitions are currently observed for the Arctic, dust availability and distribution in the Arctic is expected to change. For extrapolating further changes, robust model considerations are required. Yet, no reliable emission and distribution scheme for HLD exists. In the northern hemisphere, Iceland is a major source – as of today the strongest single one - delivering dust to the Arctic. The main directions of export are assumed to be in southerly and north-easterly direction. Icelandic dust can travel distances of more than 1,000 km, e.g. to Svalbard, Spitsbergen, and therefore impacts at least a large part of the Atlantic sector of the Arctic. Although of significant importance for understanding the Arctic environment, only few data sets exist on Icelandic dust concentrations and their temporal and spatial patterns so far. In particular, measurement data on dust export and long-term data are sparse. To overcome this lack of data and in order increase the level of understanding of Icelandic dust export as potential conceptual model for HLD generation, the HiLDA project, is proposed. HiLDA combines short-term intensive observation periods (one month) and long-term baseline monitoring (two years) with detailed numerical simulations by a state-of-the art atmosphere-dust model. Measurement locations, time periods and intervals have been chosen in accordance with the requirements of serving as model input, as well as of yielding information on source-near and regional patterns. Besides two major dust sources probed during intensive operation periods for assessment of dust emission processes, dust export from Iceland is observed by two continuously-operating coastal stations in the major outflow directions. In addition, the regional scale is covered by observations on Faroe Islands, Andoya, Jan Mayen, and Svalbard. At all locations, dust microphysics and dust composition is observed, so systematic dependencies and evolution during transport can be derived. Ultimately, model simulations will allow for interpreting the measurement in a broader context eventually revealing the role of HLD in the Earth system in general and for the Arctic environment in particular.