Characteristics of Recent Severe Haze Events in Korea and Possible Inadvertent Weather Modification

The quantitative understanding of aerosol-cloud-precipitation interactions is still insufficient despite substantial amounts of previous efforts to solve this problem since it has inherent complexity. Probably we might need overwhelming aerosol forcings well beyond cloud and precipitation variabilities in order to identify and attribute its discernible effect on clouds and precipitation. Korea recently suffered from severe haze episodes that appear to be largely long-range transported from China, which could be made the best use of to evaluate the hypothesis of enhanced aerosol impacts on clouds and precipitation. A couple of severe hazes in January 2013 originated from eastern China were also observed in the mid-Korean peninsula. The cloud systems overlapped with aerosol plumes seemed to be modified such that drizzle-type light precipitation lasted longer within half a day than the operational weather forecast because precipitation might be extended at a less rate due to increases in number concentration of smaller cloud droplets as shown by a sensitivity test using the WRF model. This study shows a possible evidence of inadvertent weather modifications by enhanced aerosols. It also implies that Korea would be a better testbed to investigate aerosol impacts on weather.