| Summary: | Dust is an important component of the earth-atmosphere system, affecting amongst other things air quality, vegetation, infrastructure, animal and human health. Iceland produces a large amount of dust, with dust storms reported frequently especially along the South Coast and in the Highlands. Nearly 20% of the country is classified as a desert with a highly erodible surface coupled with frequent windy conditions from synoptic and mesoscale weather systems which favors dust storms to occur. In addition, new material is constantly being created through glacial, fluvial, and aeolian erosion processes, as well as input of volcanic ash from volcanic eruptions. Due to the volcanic nature of Iceland, most of the material that can be suspended regularly in the atmosphere is of volcanic origin, changing critical properties of the dust relative to other major dust source regions outside of Iceland. Fresh ash, a young component of Icelandic dust, can have different properties than more aged dust particles. The different properties of fresh and aged Icelandic dust, and dust from outside of Iceland changes the parameters used for the measuring, modeling, and forecasting of dust. Fresh volcanic ash can be distinguished from aged dust particles in the lab by observing particle shapes and surface textures. Observations of dust transport, for example by satellite imagery and by weather observers, can help identify if a dust storm originated from a source area rich in young ash or more aged dust. In situ particle counting instrumentation in conjunction with meteorological measurements as well as numerical models can be used to determine when a large dust event has occurred. Synergistic use of these techniques is used to show that fresh ash provided by volcanic eruptions have a smaller impact on the number of dust events than previously assumed. Only volcanic eruptions with a Volcanic Explosive Index of 3 or greater, occurring outside of the winter season, increase the number of dust events in Iceland above the background numbers. ...
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