Fine Structure, Instabilities, and Turbulence in the Lower Atmosphere: High-Resolution In Situ Slant-Path Measurements with the DataHawk UAV and Comparisons with Numerical Modeling

AbstractA new platform for high-resolution in situ measurements in the lower troposphere is described and its capabilities are demonstrated. The platform is the small GPS-controlled DataHawk unmanned aerial system (UAS), and measurements were performed under stratified atmospheric conditions at Dugway Proving Ground, Utah, on 11 October 2012. The measurements included spiraling vertical profiles of temperature and horizontal wind vectors, from which the potential temperature θ, mechanical energy dissipation rate e, Brunt–Vasala frequency N, temperature structure parameter CT2, Thorpe and Ozmidov scales LT and LO, and Richardson number Ri were inferred. Profiles of these quantities from ~50 to 400 m reveal apparent gravity wave modulation at larger scales, persistent sheet-and-layer structures at scales of ~30–100 m, and several layers exhibiting significant correlations of large e, CT2, LT, and small Ri. Smaller-scale flow features suggest local gravity waves and Kelvin–Helmholtz instabilities exhibiting ...