Satellite-based evidence of dust emission over Northern Canada

Abstract

High-latitude dust (HLD) is receiving growing research interest for its relative impacts in the Arctic. Direct knowledge of HLD emission locations is limited, leading to a common lack of representation in global models. Using the Frequency of Occurrence (FoO) of extreme Dust Optical Depth (DOD > 0.5), derived at high resolution (0.1° × 0.1°) from twenty years (2002–2022) of MODIS data, we present semi-quantitative evidence that dust emission sources are widespread across the Canadian Arctic Archipelago. We also present qualitative supporting evidence from VIIRS and CALIPSO satellite aerosol type “dust” classifications, and some practical challenges of comparing MODIS data to two AERONET sites co-located with dust emission sources. The HLD emission hotspots identified in the “Canadian Arctic Dust Belt” correspond to surfaces with high potential for dust emission in the G-SDS-SBM dataset. There are more areas where emission hotspots are observed but emission potential is low than the opposite case; additionally, three considerable areas of dust emission are identified at lower latitudes in mainland Canada. Spatially averaged across the “Canadian Arctic Dust Belt” (70–80° N, 125–75° W), annual mean time series (2003–2022) of FoO (DOD > 0.5) suggest some increase in the frequency of dustiness with time, consistent with our understanding that HLD emissions increase in a warming climate, but without statistically significant anti-correlation to snow cover. These results further motivate model development to include HLD sources, suggest future field observation locations, and provide a novel observational basis for evaluating them with satellite data, which can be further refined.