Implementation of a Silver Iodide Cloud-Seeding Parameterization in WRF. Part II: 3D Simulations of Actual Seeding Events and Sensitivity Tests

Abstract

Four cloud-seeding cases over southern Idaho during the 2010/11 winter season have been simulated by the Weather Research and Forecasting (WRF) model using the coupled silver iodide (Agi) cloud-seeding scheme that was described in Part I. The seeding effects of both ground-based and airborne seeding as well as the impacts of model physics, seeding rates, location, timing, and cloud properties on seeding effects have been investigated. The results were compared with those from Part I and showed the following: 1) For the four cases tested in this study, control simulations driven by the Real-Time Four Dimensional Data Assimilation (RTFDDA) WRF forecast data generated more realistic atmospheric conditions and precipitation patterns than those driven by the North America Regional Reanalysis data. Sensitivity experiments therefore used the RTFDDA data. 2) Glaciogenic cloud seeding increased orographie precipitation by less than 1% over the simulation domain, including the Snake River basin, and by up to 5% over the target areas. The local values of the relative precipitation enhancement by seeding were ~20%. Most of the enhancement came froi"n vapor depletion.3) The seeding effect was inversely related to the natural precipitation efficiency but was positively related to seeding rates. 4) Airborne seeding is generally more efficient than ground-based seeding in terms of targeting, but its efficiency depends on local meteorological conditions. 5) The normalized seeding effects ranged from 0.4 to 1.6 under various conditions for a certain seeding event.

Assessment of Ground-Based and Aerial Cloud Seeding Using Trace Chemistry

“…Two recent cloud seeding projects utilized snow chemistry data to inform statistical models or to parameterize weather model inputs: SNOWIE and the WWMPP [10][11][12]. Models are rapidly advancing the ability to predict when and where AgI are active [10], but considerable uncertainties remain in these models regarding how nucleation and subsequent transport and deposition are parameterized [12].…”

Advances in the Evaluation of Cloud Seeding: Statistical Evidence for the Enhancement of Precipitation

“…In the White Top Plan of the grain producing area in Missouri in Midwestern United States, rainfall decreased in areas near the downwind of cloud seeding line, but it increased farther downwind significantly (Decker et al, ). In addition, the dynamic effects caused by cloud seeding make the target area appear not only in the downwind direction of the operation site but may also affect the crosswind or even upwind direction (Wang et al, ; Xue, Hashimoto, et al, ; Xue, Tessendorf, et al, ).…”

“…It compares the actual value with the estimated natural value with the assumption of no catalysis to establish the corresponding evaluation indicators to analyze the effect of cloud seeding (Breed et al, ; Gabriel, ). Most previous studies selected precipitation to conduct analysis, and the results showed that the relative effects of artificial precipitation enhancement operation are about 5%–45% (e.g., Gabriel & Gagin, ; Gabriel, ; Gagin & Gabriel, ; Griffith & Yorty, ; Jia et al, ; Koloskov et al, ; Li et al, ; Morrison et al, ; Solak et al, ; Xue, Hashimoto, et al, ; Xue, Tessendorf, et al, ; Woodley et al, , ; Wu et al, ; Wurtele, ; Zeng et al, ; Zhai, ; Zhai et al, ). Despite important progress, many critical issues or challenges remain to be solved, such as natural fluctuation of spatial and temporal distribution of precipitation, lacking complete and systematic understanding of the processes of artificial catalysis and physical mechanism of cloud seeding, and limitation of the application of statistical methods.…”

Iodization‐Induced Reversible Wettability in Nanostructured Ag Films

“…The applications of AgI in photography, ice nucleation, cloud seeding, the superionic devices, and photocatalysis are well known . AgI thin films are also being investigated as resistive memories and optical waveguides .…”