Analysis of cold pool breakup in complex topography and comparison with laboratory model results

A major aim of the Terrain-Induced Rotor Experiment (T-REX), carried out in Owens Valley of California, was to investigate the dynamics and flow patterns that underlie and dominate the destruction of cold pools in complex terrain. These so-called cold pools are characterized by a positive potential temperature gradient and are a common feature in valleys and basins during synoptically inactive nocturnal conditions. A discussion of the temporal evolution of temperature and velocity profiles during the morning transition of cold pools observed during EOP 2 of T-REX near mid-valley using the ASU sodar/rass and lidar systems will be given. Evidence is given that supports the hypothesis that the newly described intrusion destruction mechanism plays a significant role during EOP 2. A brief comparison will be made between EOP 2, the most ideal case, and EOPs 3 and 4, noting significant differences in inversion characteristics and evolution.

Laboratory experiments have also been performed to simulate and characterize the breakup of cold pools under a range of parameterized conditions. A v-shaped tank was employed, filled with a working medium of thermally stratified water. The aluminum walls of the tank were heated to simulate morning transition insolation and cold pool breakup. Temperature profiles at tank center were acquired and images of the flow patterns were captured by using a fluorescent dye injection procedure. Morning transition temperature profiles from Owens Valley are compared to those from the controlled experimental laboratory conditions to help determine the dominant cold pool breakup mechanism in the field.