A Field Study of Cold Pool Evolution

Cold pools that form in midlatitude basins during the winter often trap pollutants near the surface. Forecasting the breakup of these pools is hampered by our current lack of understanding of the physical processes involved in the evolution of cold pools. During the winter of 1998-99, Pacific Northwest National Laboratory carried out a small field measurement program in the Columbia Basin of south-central Washington to investigate the physics of cold pools. Wind and temperature data were collected continually from a wind profiler/RASS, from the 122-meter Hanford Meteorological Tower, from the 30-station Hanford Meteorological Monitoring Network, and from pseudo-towers of inexpensive temperature sensors installed at 100-m elevation intervals on Gable Butte and 1100-m Rattlesnake Mountain. From November through March, several inversion formation and breakup cycles were observed, including two particularly well-developed cold pools. This paper describes the measurement program and illustrates from the data the progression of cold pool destruction and the associated atmospheric structure.