Simulations of seeding effects on winter orographic clouds using a two-moment microphysics scheme with a AgI point source module

While research-orientated weather modification programs try to quantify seeding effect (precipitation enhancement by hygroscopic seeding or glaciogenic seeding) statistically through observations, the detailed physical chain of events following seeding operations is difficult to measure and thus has to be investigated by numerical models. Recent studies have demonstrated that properly configured models can reproduce storm-total orographic precipitation within about 10% of surface observations. This improvement is attributed to fine enough resolutions to represent the terrain details and associated flows, improved microphysics scheme and improved moisture advection.

This study will simulate two seeding cases from 2009 and 2010 of the Wyoming Weather Modification Pilot Program using the Weather Forecast and Research model version 3.1 driven by the North American Regional Reanalysis data. Two domains with a two-way nested domain are applied to cover the broad area of the program and detailed topography of the target regions. The horizontal resolutions for these two domains will be 2.5 km and 500 m respectively. The Thompson microphysics scheme coupled with an explicit AgI point source module is used to investigate the detailed microphysical processes associated with the seeding events.

The results will be presented on the conference.