Case study of turbulent fluxes during a wintertime persistent cold air pool in the Salt Lake Valley

Local turbulence processes during the formation, maintenance and destruction of persistent cold air pools are relatively unknown. A wide variety of mechanisms are involved in the formation and destruction of persistent cold air pool that contribute to this problem. In this work, two persistent cold air pool episodes were observed during February 2004 in the Salt Lake valley. The two inversion episodes were separated by a brief ‘washout' period when the persistent cold air pool was destroyed. The current research presents near surface turbulence measurements including fluxes of heat, momentum and water vapor during February 2004 from a measurement site located at the southwest end of the Salt Lake valley. The turbulence levels during the persistent cold air pool episodes compared to turbulence during a period that was not under the influence of a cold air pool were reduced by over 70%. Meteorological data from various regional weather monitoring stations have been utilized to conjecture two types of mixing scenarios during a persistent cold air pool namely, a surface based inversion scenario and a well-mixed surface layer capped by an elevated inversion. It is shown that both of these types of cold air pools can exist during a single persistent cold air pool episode.