Wave-induced turbulence: Insights from T-REX

During the Terrain-induced Rotor Experiment (T-REX) in March and April 2006 highly turbulent flows 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 wave and turbulence structures in the lee of the Sierra Nevada in a number of research missions under strong lee-wave conditions. In situ measurements by the UWKA and the network of surface sensors have been used to examine strongly turbulent flow regions documented by the UWKA and their relationship to flow structures over and within Owens Valley in the Sierra Nevada lee.

Sufficiently strong signal returns from the Wyoming Cloud Radar (WCR), a remote sensor onboard UWKA, 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 and rotor clouds over Owens Valley. The dual-Doppler analyses of the WCR data reveal the presence of fine-scale structures within rotor clouds. This remote sensing data was used to quantify the intensity of horizontal vorticity and scales of motion within rotors.

In this talk we will review the T-REX findings and put them in a broader context of aviation safety hazards in complex terrain, drawing comparison with some other mountain ranges that are known for aviation hazards associated with mountain lee waves.