Classification of precursory weather patterns prior to high PM10 events over the Korean Peninsula

In this study, we investigated precursory regional weather patterns prior to the high PM10 events over Korean Peninsula. The criterion for high-concentration PM10 events was set at 150 ug/m3 per day, referring to the “bad” among air environmental standards. In order to examine the regional weather pattern prior to the high PM10 events, the pressure fields of upper-level and lower-level were simply synthesized expecting the existence of clear signature of stagnant weather pattern. However, the resulting patterns were statistically insignificant around East Asia. We further investigated a possibility of existence of multiple precursory patterns partly offsetting each other.  Through the synoptic analysis of each case, we found that precursory weather patterns can be easily partitioned as two groups: 1) pre-existing persistent ridge and 2) Decaying east Asian cold-surge. In the case 1), persistent ridge embedded in an overall positive AO pattern sustains over East Asia both before and after the high PM10 event causing long-term accumulation of fine dusts over Korean Peninsula. In this case, warm surface temperature dominates before and after the high PM 10 event. In the case 2), upper-level trough over east Asia rapidly moves eastward along with cold-surge evolution and stagnant high pressure system sits in over Korean peninsula just after the timing of high PM event. Surface temperature suddenly changes from cold to warm dramatically.