A 21-year evaluation of MODIS Aerosol Optical Depth retrievals during Icelandic dust events

The wind-blown entrainment, transportation, and deposition of mineral dust originating in the high latitudes plays a significant role in atmospheric, cryospheric, marine and terrestrial environments at the regional scale. However, the intermittent nature of dust events occurring over broad spatial scales is difficult to capture from field studies alone. Remote sensing datasets are well-suited to overcoming some of these spatial limitations, and while they have been effectively used to characterise and understand dust activity across the major global hotspots, they lack application in high latitude dust regions. The use of surface observations of dust, such as those recorded at meteorological stations, is an important step in assessing the value of data retrieved from space. Meteorological observations have an established application in monitoring wind erosion and dust activity at broad spatial and temporal scales, however their use as a comparative method for evaluating data retrieved from remote sensing remains under explored.

This research presents the first systematic comparison of remotely-sensed data and ground-based present weather dust codes for a high latitude region, using Iceland as a case study. Remote sensing datasets including Aerosol Optical Depth, Angstrom Exponent and Single Scattering Albedo are derived from the MODIS Level-2 Aerosol Product at 10 km resolution, has and have been evaluated against coded present weather reports of dust obtained from 23 Icelandic meteorological stations for the study period 2001 – 2022. Preliminary analysis indicates that Aerosol Optical Depth is elevated for dust constrained days which allows some inference about the seasonality of dust activity.  Further comparative testing of ground-based and remotely-sensed data may create opportunities for better understanding the opportunities and limitations associated with remote sensing of high latitude dust activity in regions where ground-based data are not available.