Abstract : L.4
T-REX EOPs II: Valley and Larger Scale Forcing of the Boundary Layer

Stephen Mobbs, Ralph Burton, Felicity Perry, Gregory Poulos, Juerg Schmidli, Simon Vosper, Ian Brooks
University of Leeds

During the Terrain Induced Rotors Experiment (T-REX), a secondary set of objectives concerned the stable boundary layer flow in the Owens Valley. These objectives were addressed in five "Extended Observing Periods" - EOPs. During periods of weak synoptic forcing, diurnal thermally forced valley flows were observed to interact in a highly complex way with the free atmosphere above the approximately two dimensional topographic barriers along each side of the valley (the Sierra Nevada and Inyo/White Mountains). In this presentation, observations of the atmospheric structure within and above the valley will be presented for several EOPs. During EOPs, radiosondes were launched from within the valley at short time intervals (1.5 - 2 hours). For two EOPs, data is available from flights of the FAAM BAe 146 aircraft within and above the valley. Aircraft data are available not only for the flow and thermodynamics but also for some chemical species. The relationship of the evolution of the near-surface flow as observed using turbulence towers and automatic weather stations to the valley-scale forcing revealed by the radiosonde and aircraft data will be presented. This will include a discussion of the chemical mixing processes and the development of multiply-layered flows.