Trends and classification of aerosol observed from MODIS sensor over Northern Europe and the Arctic

Abstract

The year-to-year emission trends of air pollutants in the middle latitudes and local Arctic regions affect PM2.5 in the Arctic. To understand the aerosol changes in the Arctic caused by these spatial emission characteristics, we investigated the long-term trends of aerosol and categorized aerosol types for nine selected regions over Northern Europe and some parts of the Arctic. The selected Arctic sector does not represent the whole Arctic, and the Arctic in the study includes Greenland, Svalbard, Iceland, and surrounding waters. For the investigation, we used aerosol optical properties observed by the Moderate Resolution Imaging Spectrometer (MODIS) sensor. Our study showed that the long-term analysis of Aerosol Optical Depth (AOD) has an increasing trend over the Arctic regions such as Svalbard (SV), Iceland (IC), Greenland (GL), and Greenland Sea (GLS) at the rates from 0.23 × 10？？ 3 to 0.73 × 10？？ 3 per year. In contrast, AOD in the some parts of Europe (EU), Northern Europe (NE), Baltic Sea (BS), and Russia (RS) continues to decrease at the rates between ？？ 0.84 × 10？？ 3 and ？？ 2.32 × 10？？ 3 per year. Furthermore, aerosol type classi？cation based on speci？c threshold values of AOD and Angstr¨om exponent presents that most aerosols are attributed mainly to 42.23% of continental clean background aerosol (CA) and 32.98% of marine aerosol (MA) for all selected regions. From a seasonal perspective, the contributions of MA are high in winter (78？85%) and less signi？cant in summer (13？17%). On the contrary, CA has a low contribution in winter (5？10%) with dominance in summer (54？63%). These ？ndings can help to improve our understanding of the future climate change and air quality in the Arctic.