Ag Deposition Comparison between WRF Simulation and Observations in the Downwind Area of the Payette Basin

Boise State University scientists collected snow silver samples in the downwind area of Payette basin in the Lost River Range using helicopter at the end of the 2015-2016 winter season under the support of Idaho Power Company. Nine downwind sites were sampled to analyze the Ag concentration and the downwind seeding signal associated with seeding operations in Payette. The preliminary results indicated that downwind seeding signals were very weak from Payette ground seeding cases while a few seeding signals were picked up for some airborne seeding cases.

This study presents the comparisons of Ag concentration between snow samples collected in the Lost River Range and WRF (Weather Research and Forecasting model) simulation results using the AgI Seeding Parameterization for two scenarios. One scenario contains airborne seeding cases on Jan. 28 and 29, 2016, which resulted in detectable Ag signals in 5 out of 9 downwind sites. The other scenario is a ground seeding case on Feb. 18, 2016, which also showed downwind signals in 4 out of 9 sites. The WRF simulations are driven by ERA-Interim reanalysis data. Different activation and scavenging processes are tested. The detailed analysis of the model results and the comparisons between model and observations will be presented at the conference.