Lower-tropospheric waves and wave-induced turbulence zones: Insights from T-REX

During the Terrain-induced Rotor Experiment (T-REX) in spring 2006 highly turbulent flows in atmospheric rotors in the lee of the Sierra Nevada were probed by the University of Wyoming King Air (UWKA) aircraft. In situ thermodynamic and kinematic data was obtained by UWKA on rotor and wave structures over Owens Valley in a number of research missions under strong lee-wave conditions. Sufficiently strong signal returns from the Wyoming Cloud Radar (WCR) were granted by the presence of ice particles within different types of clouds associated with the wave/rotor system, including mountain cap clouds over the Sierra crest, "spill over" clouds over the eastern Sierra slopes as well as roll clouds over Owens Valley.

In situ measurements by the UW King Air have been used to examine the range of different flow structures over Owens Valley, including trapped lee waves, low-level wave breaking, and hydraulic jumps and their relationship to attendant strongly turbulent flow regions within Owens Valley. In a selected number of missions, during which returns from the roll clouds were sufficiently strong to permit dual-Doppler analyses, the results of this analyses reveal a wealth of fine-scale structures within the roll clouds in the upper part of the rotor circulation. Wave-induced pressure perturbations determined from the aircraft measurements are compared with the surface pressure perturbations derived from the network of surface pressure sensors in Owens Valley. High-resolution real-data COAMPS simulations are used to provide further insight into the evolution and structure of the flow field over the Sierra Nevada and Owens Valley, including waves and rotors.