객관적 황사판별을 위한 LIDAR 임계값 및 선행시간 연구

Abstract

With accelerating global warming, the desertification of inland areas is induced by excessive evaporation in China and Mongolia. In addition, owing to overgraze, overplant, and overplow for food security for the population growth in China, the grassland is gradually becoming desolated and the extent of the source of Asian dust becomes wider. The increase of Asian dust area made the high intensity and frequency of Asian dust to Korea, which has a bad influence on health and industry. Therefore, based on LIDAR, this study will estimate precedent time of Asian dust which contributes to forecast of Asian dust and critical valve of LIDAR for objective distinction of Asian dust in order to minimize the damage from Asian dust. This study analyzed and compared cases in Gunsan region in the past one year(from 17 Mar. 2007 to 16 Mar. 2008) when there was Asian dust most frequently and for the period from 8 Apr. 2006 to 9 Apr. 2006, from 31 Mar. 2007 to 2 Apr. 2007 when strong Asian dust was observed by using LIDAR, wind profiler, APS, PM10, and Satellite. Although there are lots of methods for detection of Asian dust, researchers tend to primarily depend on fine particle concentration of PM10 because PM10 is useful on diagnosis of Asian dust by easy application of quantitative data and extensive observational networks. However, the objective distinction between Asian dust and pollutant with PM10 is limited in case of pre-phase of yellow-dust watch (criterion of PM10 : fine particle concentration is under 400㎍/㎥). Therefore, in this study, LIDAR that can measure vertical distribution of aerosols is mainly utilized, and PM10, APS, wind profiler are utilized as well. The observed cases of Asian dust at PM10 concentration below the max-average 309㎍/㎥ show stair form with the increasement of LIDAR wave, over 0.08 depolarization ratio at 2 to 4km in air, and the variation of over 0.05 depolarization ratio before observing Asian dust at precedent changes. The cases of observed Asian dust under max-average 255㎍/㎥ in PM10 concentration which are suspected as pollutants show slight or mere change and look like verticality. The depolarization ratio(DPR) displayed less than 0.05 at 2 to 8km in air, and precedent changes give the variation of DPR below 0.02 before observing Asian dust. Analysis result of precedent time of Asian dust by using LIDAR is that DPR increase before average 4.3 and 12hours leading to the eye and max concentration of PM10.