Comparisons between WRF simulations and ground observed trace chemistry

A silver iodide (AgI) point source module which is capable of simulating extra tracers such as Indium (In) and Cesium (Cs) has been implemented into the Thompson microphysics scheme of the Weather Research and Forecast (WRF) model to simulate 5 real seeding cases over Payette region in Idaho during winter seasons in 2004 and 2005 using 667 m horizontal grid spacing. The numerical results are compared to ground observations of trace chemistry such as Ag concentration, In concentration and Ag/In ratio that were taken by Desert Research Institute (DRI).

The results show that: 1) WRF seeding simulations reproduced the observational patterns of Ag concentration and Ag/In ratio reasonably well. 2) Ag concentrations on ground usually do not align with precipitation enhancements but total Ag mass deposited on ground collocates with precipitation enhancements. 3) High Ag concentrations were found close to ground generators in ground seeding cases which agree with Warburton et al., 1995. These results will be presented at the conference.