Possible Aerosol Effects on Clouds and Precipitation over Korea during the January 2013 Severe Haze Episode

Aerosols effects on clouds and precipitation are one of the key components of the climate system and the hydrological cycle. However, the level of scientific understanding concerning aerosol-cloud-precipitation interactions is still low (Boucher et al., 2013), because these processes are linked to many factors like cloud regime (Stevens and Feingold, 2009) or meteorological condition (Loeb and Schuster 2008, Su et al., 2010; Kim et al., 2008; 2012), leading to a high process complexity (Andersen and Cermak, 2015). In January 2013, heavy air pollution was observed over most parts of northern and central China (Tao et al., 2014; Uno et al., 2014). It was also identified in Korea with a time lag of a couple of days (12 January 2013). The episode has synoptic setting such as weak trough at 850hPa moving through the northern Korean peninsula during 11-12 January, leading to the dominant westerly winds over Korea. PM10 mass concentrations increased significantly over Korea since early 12 January with exceeding over 200ug/m3. Interestingly, Korea Meteorological Administration (KMA) forecasted precipitation would end at noon, but the precipitation lasted until 21 LST in the mid-Korean peninsula. In contrast, there was little precipitation over the southern part of the Korean peninsula. Based on the above observation, to understand the aerosols effects on clouds and precipitation in Korea, we have analyzed the relationship of PM10 to MODIS-derived cloud properties (Cloud Optical Depth; COD, cloud effective radius; re, Liquid Water Path; LWP) in terms of north-south gradient. We found the smaller effective radius in the mid-Korean peninsula, with an increase in COD, whereas a larger effective radius and reduced COD shown in the southern-Korean peninsula. It implies the increased aerosol loadings transported from China can modify cloud microphysical properties over the mid-Korean peninsula, thereby affecting precipitation distribution and lasting period. Meteorological environment condition will be also checked out especially on the water vapor dependence along with variations in cloud properties. The quantitative evaluations of its modification need more detailed modeling works.