Studies of High-Resolution Turbulence, Stratification, and Instabilities in the Nighttime Boundary Layer

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As part of the CASES-99 program (Cooperative Atmosphere-Surface Exchange Study-1999), the PI measured the temperature, pressure, humidity, and wind velocity with high resolution in time and altitude using instruments suspended from a tethered kite or, in calm conditions, a tethered blimp. Preliminary analysis of the data has revealed sharp temperature inversions, intermittent bursts of turbulence, and apparent wave phenomena, all with unprecedented resolution. This grant supports the continuing analysis of CASES-99 data. The analysis is focused on the following objectives:(1) statistical characterization of the turbulence in selected homogeneous layers;(2) investigation of turbulence in the vicinity of horizontal interfaces separating layers with different turbulence characteristics;(3) study of turbulence intermittence, including calculation of spectra of the energy dissipation rate e and the temperature structure parameter Ct2;(4) examination of the structure of Kelvin-Helmholtz instabilities and other wave phenomena in collaboration with large-eddy simulation modelers;(5) entering other collaborations with CASES-99 researchers in the analysis of different data sets.This research advances the fundamental understanding of atmospheric turbulence and enables improved parameterization of the diffusion and vertical transport of heat, momentum, and material in the nocturnal atmospheric boundary layer.