State Water Resources Research Institute Program


Project ID: 2007WY39B
Title: Detecting the Signature of Glaciogenic Cloud Seeding in Orographic Snowstroms in Wyoming Using the Wyoming Cloud Radar
Project Type: Research
Start Date: 3/01/2008
End Date: 2/28/2010
Congressional District: 1
Focus Categories: Water Quantity, Climatological Processes, Hydrology
Keywords: Cloud seeding, Cloud radar, Aircraft measurements, Weather modification
Principal Investigator: Geerts, Bart
Federal Funds: $ 15,600
Non-Federal Matching Funds: $ 135,623
Abstract: This proposal is linked to the ongoing Wyoming Weather Modification Pilot Project. In Year 1 of this proposal, specifically in February 2008, the University of Wyoming King Air (WKA) research aircraft conducted two successful flights over the Medicine Bow Range. These flights took the aircraft repeatedly along fixed tracks over and incrementally downstream of select silver iodide (AgI) generators on the ground, both during on (seeding) and off (no seeding) conditions in equal proportions. Detailed Wyoming Cloud radar transects and flight-level data were collected along each flight leg. The data show the presence of intense turbulence in the boundary-layer orographic cloud. This implies that the AgI seed material mixes quite effectively in the main precipitation growth layer along the upwind slopes, better than predicted by NCAR's high-resolution WRF model simulations. Two flights clearly are insufficient to detect the cloud seeding signature: the natural spatial variability in the snow concentration downstream of AgI plumes overwhelmed any cloud seeding signature.

We plan to fly the remaining flight hours (11.8 hours) under this project between 1 February and 31 March 2009, while the WKA is fully instrumented for an independent NSF-funded project. Thanks to this project, the WKA will also carry an integrated supercooled liquid water radiometer and an up- and downlooking lidar, the Wyoming Cloud Lidar. The combination of the lidar and radar will yield new insights into the depletion of supercooled water and the growth of ice crystals downstream of AgI plumes. The availability of these additional instruments through the NSF project represents a unique low-cost window of opportunity. Therefore additional WKA flight time (9.2 hours) has been requested in another USGS-WWDC grant proposal (pending), in order to conduct a total of five full flights during WAICO. All five flights will follow precisely the same flight track over the Medicine Bow Range and downwind of the generators, as the two Feb 08 flights, thus we will have 7 cases to construct composite radar and lidar transects, and thus composites of snow and supercooled water concentrations.

Progress/Completion Report, 2007, PDF
Progress/Completion Report, 2008, PDF
Progress/Completion Report, 2009, PDF

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