The Effects of Spring and Winter Blocking on PM10 Concentration in Korea

Abstract

Atmospheric blocking is known to be related to locally developed abnormal climate of the Korean Peninsula, such as heat and cold waves. However, little attention has been devoted to the effects of blocking on the fine dust concentration over Korea. In this study, we analyze the connection between the monthly frequency of blocking occurrence and high particulate matter smaller than 10 μm in diameter (PM10) concentration events in Korea. Our analyses are limited to winter (DJF) and spring (MAM) when both the blocking and high PM10 events tend to take place most frequently. During winter, significant and positive correlations are found in the North Pacific, while significantly negative values are seen over Ural-Siberia. A high PM10 concentration tends to be accompanied by negative (positive) pressure anomalies over Siberia (North Pacific). However, while examining atmospheric fields associated with the high PM10 events, we find that the high PM10 events show two different types of atmospheric fields depending on the strength of wind speed over Korea. When the local wind speed over Korea is weaker than normal, the connection with the North Pacific blocking is strengthened, whereas, the connection with the Ural-Siberia blocking is enhanced when the wind speed is stronger than normal. However, to increase the occurrence of the high PM10 events, both types feature a strong meridional pressure gradient caused by a high pressure system forming over Siberia. This is accompanied by a strong upper tropospheric zonal wind from China and Mongolia to Korea.

Quantifying the Impact of Synoptic Weather Systems on High PM2.5 Episodes in the Seoul Metropolitan Area, Korea

“…The three upper-level meteorological variables are positively correlated; for example, the southerly wind anomaly at 850 hPa brings warm and moist air from CHANG ET AL. the ocean to thicken the layer between 850-and 500 hPa over the region, resulting in a positive 500-hPa height anomaly (Yun & Yoo, 2019). On the other hand, the southeasterly wind overwhelms the vertical ventilation of PM 2.5 by advecting warm moist air into the SMA to increase static stability, while weak surface wind reduces horizontal ventilation .…”

Linking air stagnation in Europe with the synoptic- to large-scale atmospheric circulation

“…They are an obvious candidate for driving air stagnation events as they are characterised by a synopticscale, quasi-stationary anticyclone (Rex, 1950), and thus provide the weak winds and absence of precipitation that define air stagnation. Blocks have been shown to increase pollutant levels in Europe (Hamburger et al, 2011;Garrido-Perez et al, 2017;Ordoñez et al, 2017;Webber et al, 2017;Vautard et al, 2018), the United States (Comrie and Yarnal, 1992) and in Asia (Yun and Yoo, 2019). The position of the North Atlantic jet stream (Ordóñez et al, 2019), the presence of subtropical ridges (Garrido-Perez et al, 2017;Ordoñez et al, 2017) and the passage of midlatitude cyclones (Leibensperger et al, 2008;Tai et al, 2010Tai et al, , 2012Leung et al, 2018) can also influence air stagnation development and pollution levels.…”

Statistical Seasonal Forecasting of Winter and Spring PM2.5 Concentrations Over the Korean Peninsula

“…In terms of air quality category of Korea, this includes both unhealthy (36–75 µg m − 3 ) or very unhealthy (76 µg m − 3 and above) air quality categories (NIER 2019 ). Also, the definition of high PM 2.5 concentration days resembles the definitions on high PM 10 concentration days in previous studies (Yun and Yoo 2019 ; Ku et al 2021 ).…”