Heat Transport by Turbulence and Submeso Structures in the Stable Boundary Layer

Abstract

We examine measurements in the very stable boundary layer using tower data and a network of flux stations in the Shallow Cold Pool experiment. Submeso motions in the very stable boundary layer significantly modulate the turbulent heat fluxes and also directly contribute to the submeso vertical heat flux. Time series include well-defined submeso structures such as microfronts, wave-like motions, and meandering but also include complex structures that are difficult to isolate. These structures significantly influence the time and height variation of the turbulent heat flux. From the 19 flux stations distributed across the shallow valley, we find that the surface heat flux with low wind speeds varies significantly on a horizontal scale of 100 m, or less, related partly to the modest topography. For this dataset, the turbulent surface heat fluxes for low wind speeds are closely related to submeso variations of the wind speed but not significantly related to variations of the stratification.