전년 동기대비 2020년 12월 국내 초미세먼지 농도 변화 요인 분석

Abstract

The observed monthly mean PM2.5 concentration in South Korea during December 2020 has decreased by 2.3 mu g/m(3), compared to that during the same month in the previous year, but the drivers of the change have been veiled yet.This study quantitatively examines the roles of the potential drivers of the PM2.5 decrease during December 2020. Air quality simulations for December 2019 and December 2020 show that the change in meteorology conditions have increased the PM2.5 concentrations by 1.4 mu g/m(3) in South Korea, but the changes in the Northeast Asian emissions have decreased the PM(2.5 )concentrations by 3.7 mu g/m(3) in the country. In addition, foreign emission impact on the nationwide PM2.5 concentrations estimated from a set of the sensitivity simulations with the Community Multi-scale Air Quality model and adjusted with the surface observations in China has increased by 1.9 mu g/m(3) in December 2020, compared to that for December 2019. It means that the upwind foreign emission condition was not helpful in the downwind PM2.5 decrease. On the contrary, the domestic impact has decreased by 4.2 mu g/m(3) over the country, which compensated the increase in the foreign impact for the month. The observed monthly mean NO2 concentrations have decreased by 5% and 8% for South Korea and the Seoul Metropolitan Area, respectively, compared to the same month in 2019. When a simple observation-based emission adjustment was applied, a 5% decrease in the national total NO, emissions for the month was estimated. The causality of NO2 decrease still needs further investigations, but the seasonal PM2.5 management and social distancing after the COVID-19 re-outbreak at the end of November might have led to the reduction in the anthropogenic emissions (i.e., NOx) and thus the PM2.5 concentrations during the month.