Simulated dispersion and long-range transport of silver iodide in winter orographic cloud seeding

Simulations of the impact of winter orographic cloud seeding with silver iodide (AgI) have been performed utilizing a newly developed AgI cloud seeding parameterization in the Weather Research and Forecasting (WRF) model for cases over the Snake River Basin in Idaho. Several cases indicate simulated seeding effects occurred well downwind of the intended target area. This paper investigates the simulated dispersion and long-range transport of AgI in such cases and evaluates the feasibility of the transported AgI to yield simulated precipitation enhancements downwind. Results from the WRF model will be compared with the HYSPLIT trajectory model to evaluate the model's dispersion of the AgI seeding agent. In addition, the relative efficiency of and requisite conditions for the dispersed seeding agent to yield a simulated precipitation enhancement downwind will also be addressed. Environmental factors (such as wind speed, direction, and stability), microphysical conditions (supercooled liquid water, temperature), as well as whether AgI undergoes any cloud processing will be presented.