A Numerical Study on Winter Orographic Cloud Seeding Experiment in Korea Using the Weather Research and Forecasting (WRF) Model

The parameterization of ice nucleation by silver iodide is implemented as a part of Morrison Double-Moment microphysics scheme into the Weather Research and Forecasting model to simulate the effects of orographic cloud seeding on the change of cloud microphysics and on the precipitation enhancement in the mountainous eastern part of the Korean Peninsula during wintertime. Three ice nucleation modes, deposition, condensation freezing and contact freezing, are considered in these simulations. When successful, cloud seeding results in the depletion of cloud drops due to riming by the ice crystals produced by the deposition and condensation freezing of the seeding materials, and eventually precipitation increases over the target area compared to that from the unseeded simulation. Sensitivity tests show that increasing the release rate of seeding materials leads to more enhanced precipitation and ice nucleation processes are sensitive to the microphysical characteristics as well as meteorological conditions. Under a certain circumstance, contact freezing is not effective in producing artificial ice crystals. Cloud seeding seems highly productive when seeding materials are released at the peak of the mountains but not when seeding materials are released at the upslope sides of the mountains. A detailed analysis will be discussed at the conference.