The Impact of the Great Salt Lake on Salt Lake Valley Persistent Cold Air Pools

The Persistent Cold Air Pool Study (PCAPS) was held in the Salt Lake Valley (SLV) of northern Utah between 1 December 2010 and 7 February 2011. The goal of the PCAPS field campaign was to obtain detailed observations of the complex physical processes that contribute to the formation, maintenance, and decay of persistent wintertime temperature inversions in a mountain valley. One of the least-understood factors influencing the evolution of persistent wintertime inversions in the SLV is the nearby Great Salt Lake. Numerous surges of cold air originating over the lake were observed to penetrate into the SLV during PCAPS, further strengthening the ambient low-level stability and contributing to episodes of dense fog and poor air quality. Wintertime Great Salt Lake cold air surges are considerably more complex than their summertime counterparts which are driven largely by differential heating between the land and water surfaces. During the winter, the horizontal temperature gradient between the Great Salt Lake and the SLV is also influenced by boundary-layer turbulence, differential mixing, cloud cover, channeled synoptic-scale flow, and persistent mesoscale cold air drainage. A comparison between observed characteristics of summertime and wintertime lake breezes will be presented and the observed impacts of wintertime Great Salt Lake cold air surges on the life cycle of persistent cold air pools in the SLV will be discussed.