Arctic AOD Seasonality: Sub-regional Variability

In situ observations of Arctic aerosols have long shown a pronounced seasonal cycle, with a characteristic peak during the springtime Arctic haze. Dramatic differences in daily insolation and surface albedo make the radiative effects of Arctic aerosols highly seasonally dependent, and considerable efforts to understand the processes contributing to Arctic aerosol seasonality are ongoing. However, observations in the region are sparse, and at some research stations aerosol burdens peak outside the haze season. As a result, the extent to which station data is representative of the broader region, and the degree to which processes governing aerosol seasonality are homogenous throughout the region, remains undetermined. In this analysis, we use k-means clustering of CALIOP AODs to define four distinct subregions north of 60N with regards to AOD seasonality. We find that most, but not all, sub-regions exhibit a peak during the spring haze season. We also find that most research stations are located in lower amplitude clusters, indicating that station data likely underrepresent the magnitude of Arctic aerosol seasonality. We further investigate station departures from the Arctic haze seasonality within this context, finding that station altitude substantially affects the observed seasonality.