Spatiotemporal Variations in Summertime Arctic Aerosol Optical Depth Caused by Synoptic‐Scale Atmospheric Circulation in Three Reanalyses

Abstract

AbstractAtmospheric aerosol affects the radiation budget, cloud cover and properties, and surface albedo of sea ice and snow over the Arctic with obvious climatological significance. However, observations are scarce and have large uncertainties. Aerosol optical depth (AOD) variability in the Arctic and its relationship with atmospheric disturbances on synoptic timescales were investigated on the basis of the JRAero, CAMSRA, and MERRA2 reanalyses. Total AODs of the three reanalyses were spatiotemporally consistent in summer, although contributions of individual aerosol species differed. Summertime AOD variability was strongly correlated with observations in all reanalyses. The predominance of organic carbon aerosol indicates that aerosols are derived mainly from biomass burning over northern Eurasia and northern North America. Differences in composites of atmospheric fields between high‐ and low‐loading days indicate that locations of synoptic disturbances are related to high‐AOD events in the Arctic. Furthermore, empirical orthogonal function analysis indicates that the first‐ and second‐largest AOD variabilities in synoptic timescales occur over northern Eurasia. This AOD variability is related to two different types of Arctic cyclone, the development of which is important in aerosol transport, aging, and deposition in summer.