Laser Ceilometer Investigation of Persistent Wintertime Cold-Air Pools in Utah’s Salt Lake Valley

Abstract

s part of the winter 2010/11 Persistent Cold-Air Pool Study in Utah?s Salt Lake Valley, a laser ceilometer was used to continuously measure aerosol-layer characteristics in support of an investigation of the meteorological processes producing the cold-air pools. A surface-based aerosol layer was present during much of the winter. Comparisons were made between ceilometer-measured and visual characteristics of the aerosol layers. A 3?4 January 2011 case study illustrated the meteorological value of time?height backscatter cross sections when used as a base map for meteorological analyses. A variety of meteorological mixing processes were illustrated using ceilometer backscatter data. The mean altitude of the top of the aerosol layer during undisturbed subperiods of the 1 December?7 February experimental period was 1811 m MSL, with a standard deviation of 185 m. The mean aerosol depth was ~500 m AGL in the 1200-m-deep valley. There was surprisingly little variation in the wintertime aerosol layer depth despite large variations in bulk atmospheric stability and ground-based fine particulate matter concentrations.