Hydraulic-jump rotors: Favorable environments for their formation

Two primary mountain-wave/rotor (MW/R) systems are thought to exist. The first is associated with MW/R systems comprising resonant waves and rotors with moderate turbulence. The second MW/R system resembles a hydraulic jump with moderate to severe turbulence within the rotors. Numerical modeling studies using steep lee topography have shown that rotor type is sensitive to relatively small changes in vertical shear within a near-mountaintop upstream inversion.

We will present results from two-dimensional numerical model studies designed to further explore atmospheric conditions and topographic features which lead to hydraulic-jump rotors. One series of simulations explores the role of upstream inversion strength and height in a sheared environment. A second series of simulations explores the role of topography, including lee-slope height and steepness, as well as the presence of a downstream mountain range (meant to replicate the Sierra Nevada and Inyo mountains). We hope to compare results of our simulations to observations collected during the Terrain-induced Rotor Experiment (T-REX).