Airborne Cloud Radar and Lidar Observations of Blowing Snow during the ASCII Project: a Possible Natural Cloud Seeding Mechanism

Blowing snow is a ubiquitous feature in mountainous areas, leading to reduced visibilities and varying distributions of snow cover. It is hypothesized that in certain conditions, snow blown from the surface could act as seeding of overlying clouds, leading to increased snowfall. However, since most observations of blowing snow have been confined to surface or tower observations, only limited information is available on the vertical structure of blowing snow throughout the turbulent boundary layer. In order to develop a more complete understanding of the blowing snow process, surface instrumentation and the University of Wyoming airborne cloud radar (WCR) were used to observe blowing snow in the Sierra Madre Mountains of south-central Wyoming. This presentation will describe blowing snow observations on two dates during the AgI Seeding Cloud Impact Investigation project. On 18 January 2012, mostly clear skies, cold temperatures, strong winds, and fresh snow led to ideal conditions for blowing snow. Initial findings from this “pure” blowing snow case will be compared with those taken during a more complex case on 29 February 2012. On this date, widespread blowing snow near the mountain peaks as well as widespread higher-level clouds and snow, reaching the surface in some places. Surface observations showed snow particle characteristics from both blowing snow and higher-level clouds. Comparison of blowing snow characteristics on these two dates, as well as possible seeding of the clouds by blowing snow particles, will be discussed.