Possible Inadvertent Weather Modification of Severe Haze Transported from China to Korea

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 amounts of previous efforts to solve this issue since it has inherent complexity and intertwined nonlinear relationship. Probably we might need overwhelming aerosol forcings well beyond natural cloud and precipitation variabilities in order to identity and attribute its discernible effect on clouds and precipitation. Korea has recently suffered from severe air pollution and extreme haze, which could further impact not only public health but also meteorology and hydrological cycles. Most severe haze episodes 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. We demonstrate several evidences of aerosol impacts on clouds and precipitation, and briefly conduct numerical simulations to explain the possible modification of clouds and precipitation with a special emphasis on January 2013.

Eight severe hazes in 2011 to 2013 were observed in the mid-Korean peninsula. In general, the clouds systems overlapped with aerosol plumes seemed to be modified such that drizzle-type light precipitation lasted longer (or delayed) within 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 with observational evidences and model results.