B.A. Boe, J.T. McPartland, T.W. Krauss, J.A. Heimbach, L. Xue, and X. Chu
Airborne and ground-based measurements of silver iodide ice nuclei were made with acoustical ice nucleus counters on and over the Medicine Bow Range of Wyoming during the winter of 2010-2011 as part of the physical evaluation component of the Wyoming Weather Modification Pilot Project (WWMPP). While the ground-based effort was conducted through most of the 15 November 15 April project season, the airborne effort was limited to February and early March.
The airborne measurements help define the limits of plume transport, whereas the ground-based efforts only confirm transport over the barrier and to (near) the target area in some cases. The two efforts, combined, provide insight into the behaviors of silver iodide plumes released from fixed, ground-based sites on the upwind (western) slope of the range. Vertical plume transport in stable conditions was confirmed to reach altitudes up to 1 km above the ridge crest, well within usual supercooled cloud boundaries. However, the plumes were not always observed at the surface sampling site on the lee side of the range.
This paper presents both ground-based and airborne observations and offers commentary on the inferences for the effectiveness of ground-based seeding in the context of the Wyoming project.