Characteristics of Precipitation Response to the Severe Hazes in Korea Peninsula

Precipitation is a key physical process related to weather, climate, and the hydrological cycles. The quantitative understanding of aerosol-cloud-precipitation interactions is still insufficient despite substantial efforts to solve this problem since it has inherent complexity. In East Asia, Korea is located in the downwind of China and often affected by long-range transported aerosols, which are expected have the inadvertent weather modification. We used observed aerosol data of surface in Seoul (SL) and Baengnyeongdo (BN) from 2011 to 2016 to classify hazes types to long-range transported haze (LH), yellow sand (YS), urban haze (UH) and mixed haze (MH) (Lee et al., 2017). To demonstrate a possible evidence of aerosol impacts on precipitation with long-range transported hazes and yellow sand, we have analyzed the difference of precipitation timing between observational precipitation and forecasting precipitation when the weather forecast failed to catch the precipitation during classified hazes, especially LH and YS. We interestingly found that precipitation timing during LH tends to coincide with aerosol variations specifically in terms of temporal covariation, which is contrast to YS, such as YS following precipitation. Precipitation timing mostly seems to be controlled by large scale synoptic forcing during the YS event, whereas enhanced aerosol loadings in severe hazes are thought to impact clouds and precipitation in temporal scale like timing of observed precipitation. So we briefly conduct numerical simulations to assess how LH could modify the clouds and precipitation. Simulated results show that cloud fraction with increased aerosol is increased, whereas precipitation rate is decreased. In spite of lacked cloud information and detailed cloud resolving simulation not represented, the results would provide an evidence of aerosol-cloud-precipitation interaction in observed and model. Further it implies that Korea would be a better tested to investigate aerosol impacts on weather. The quantitative evaluations of its results need more detailed modeling works using another cloud physical scheme.