Interaction between slope flows and transient mesoscale modes

Downslope drainage flow and interaction with wave-like motions and other transient mesoscale motions are examined using data collected from three 32-m towers and 7 surface stations deployed along a slope in central Utah. In one scenario, collapse of the wind field in the basin leads to buildup of cold air. This cold air advances upward along the slope and temporarily eliminates the drainage flow. In addition, the drainage flow is modulated by wave-like motions and soliton events of unknown origin. The drainage flow is typically not as cold as air at the bottom of the slope, implying that the drainage flow overrides colder air in the basin. The data do not support the prevailing concept where downslope flow acceleration leads to shear-generation of turbulence and subsequent warming, at least not as a dominating influence. The thermal belt at mid slope is viewed as not only warmer air but much greater temperature time variability compared to lower on the slope. The flow along the slope will be visualized in terms of cross section animations of the wind and temperature fields.