Cold-season atmospheric conditions associated with sudden changes in PM10 concentration over Seoul, Korea

Abstract

Previous studies have intensively studied the atmospheric conditions associated with high- and low-PM10 (particulate matter < 10 μm) episodes according to air quality standards. However, the association with sudden changes in PM10 concentration has not been clearly understood. Here we defined a PM10 change of above one standard deviation as a sudden change and divided these changes into PM10-increasing days (294 days) and PM10-decreasing days (277 days). We then investigated the atmospheric conditions concerning sudden changes in PM10 in Seoul, Korea during 17 cold seasons (October to March) from 2001/2002 to 2017/2018. This study used the local and synoptic atmospheric variables obtained from ECMWF ERA-Interim and ERA5, and aerosol optical depth from MODIS/Terra. On PM10-increasing days, a high-pressure anomaly was dominant in the Korean Peninsula's upper and lower atmosphere. A southerly wind, intense atmospheric stagnation, and high aerosol optical depth over the eastern region of China may also have been responsible for the increase in PM10 regardless of the preceding concentration of PM10. On PM10-decreasing days, the prevailing atmospheric pattern was subject to the preceding concentration of PM10. From the moderate (40–80 μg m−3) to the lower concentrations, a robust and low-pressure anomaly favorable for dispersion of PM10 was dominant over the Korean Peninsula. In contrast, from the high (>80 μg m−3) to the moderate concentrations, there was no distinct pattern except for a high-pressure anomaly in the upper atmosphere. These results improve our understanding of the mechanisms behind the sudden changes in PM10 due to atmospheric conditions over East Asia.