Elevated layering in the Owens Valley observed during T-REX

During the T-REX (Terrain-Induced Rotors Experiment) campaign, numerous examples of elevated layers were observed in the Owens Valley using radiosondes, topographically-elevated ground stations, the FAAM BAe 146 aircraft and other remote sensing instrumentation. In several cases, these layers take the form of southerly along-valley flow between surface northerly flow below and synoptic northerly or westerly flow aloft. At other times, steady, vertically-confined jet layers formed. The elevated wind shear layers were observed to be associated with abrupt changes in chemical composition (carbon monoxide and ozone) indicating different airmass origins. This paper will describe the evolution of the layering through diurnal heating cycles with the aim of explaining the generation of the layering. We will discuss the roles of synoptic and valley-scale forcing, thermal forcing at the surface and inflows/outflows from side valleys. Some high resolution numerical simulations will also be presented and will be related to the spatio-temporal evolution of the valley flows observed through a meso-net array.