한반도 내 황사의 발달과 소멸에 관한 역학적 분석

Abstract

n this study, change of an air current with concentration of PM10 around the western coast of Korean peninsula, and the transportation of yellow-sand associated to synoptical weather condition were analyzed. Based on these analysis, influence of yellow-sand and its regional distribution were investigated. In Case1, weather chart indicated that South Korea was effected by a trough at the edge of low pressure. At 0400 UTC on 2 Mar. 2008, concentration of PM10 increased at the entire of the analysis points and the yellow-sand developed around the southern region under 37°N. The developed yellow-sand moved to the eastward showing its dissipation. In Case2, South Korea was influenced by a trough located between the north and south direction, since the edge of low pressure and the forward area of a high pressure were located over South Korea. NCEP/NCAR reanalysis result indicated the dense intervals of isobarics and relatively strong westerly wind over 20㎧. At 2300 UTC on 19 Feb. 2009, yellow-sand started to enhance the number concentration of PM10 around the northwestern coast of Korean peninsula (37-38°N, 124-125°E). The enhanced yellow-sand moved southeastward, showing its enlargement of its area through whole nation until 1900 UTC on 20 Feb. 2009, and gradually extinguished. In Case3, by influence of a trough located in the west and east direction, westerly and southerly winds mainly blew in South Korea, hence those influenced to the passage of the yellow-sand. At 2300 UTC on 15 Mar. 2009, the yellow-sand was not found in the southern region, even though the yellow-sand moved to south-eastward from the northwestern coast (37-38°N, 124-125°E). At 1500 UTC on 16 Mar. 2009, redevelopment of the yellow-sand around the northwestern coast (37-38°N, 124-125°E) was found during 4 hours, and its was subsequently dissipated. Updraft and downdraft and its associated variation of PM10 concentration after the yellow sand flows to the analysis area were analyzed. As the result, Related with increasing PM10 concentration, two types of the meteorological phenomena were shown. First, low-level divergence (≤ 900 hPa) and its associated updraft and upper-level convergence (800 - 850 hPa) were found. Second, low-level convergence and its related downdraft and upper-level divergence were observed. Synoptically, South Korea was influenced by a trough since the edge of low pressure and forward area of high pressure were located over South Korea with relatively strong westerly winds. We concluded that there are some relation to the enhancement and dissipation of the yellow sand; 1) regional difference in the wind direction and speed, 2) vertical updraft and downdraft at 800 hPa, and 3) variation of horizontal divergence.