Frequent Weak-wind Boundary Layers Using New Analysis Techniques in the Space-time Domain

Northwest Research Associates, Incorporated, Seattle WA

Investigators

Abstract

This study seeks to improve our understanding of the interaction of weak wind flow in the lowest layer of the atmosphere and generation of turbulence in gently sloping terrain. An improved understanding of weak-wind boundary layers could potentially lead to more accurate modeling of the formation of cold pools, damaging frost (including impact to local vineyards), fog formation, and dispersion of contaminants. This study seeks to investigate weak-wind boundary layers using detailed spatial-temporal measurements. These boundary layers demonstrate non-stationarity and the turbulence in them is generally in a non-equilibrium state with the mean flow. Previous studies of such boundary layers were mostly limited to temporal data at fixed locations, and therefore could not take into account hysteresis when investigating scaling properties. This study analyzes detailed spatial-temporal data to form a more complete picture of boundary layer structures. The evolution of the structures and the impact of the sub-mesoscale motions will be investigated.