Abstract : 2D.3
Airborne observations of trace chemical species during T-REX

Felicity Perry, Jim Mcquaid, Stephen Mobbs, Simon Vosper
flea@env.leeds.ac.uk
Institute for Atmosperic Science

During the Terrain Induced Rotor Experiment (T-REX) the FAAM BAe 146 aircraft made dedicated flights over the Sierra Nevada range and the Owens Valley under rotor and gravity wave conditions in order to observe profiles and vertical exchange of trace chemical species. During Extendended Observation Period 02 (EOP02) a strong inversion was observed in association with an intense cold pool which formed overnight in the Owens Valley. At the top of the inversion a signicantly elevated layer of ozone was seen coupled to low carbon monoxide, both indicative of air which has descended from aloft. We will focus on characterising the vertical profiles of chemical species and physical parameters and will attempt to interpret these profiles in terms of advection on the valley, gravity wave and larger scale flows.

The effect of the inversion is examined by intercomparison with a similar cold pool flight, EOP01, which did not have an inversion. A similar sortie was flown and increased levels of ozone were not seen within the Owens Valley. The ozone maximum during EOP02 raises the question of how this high ozone concentration air is maintained below the inversion, as inversions are regions of reduced vertical mixing.

We look at this case in detail from a dynamical and chemical point of view. Back trajectory and proposed chemical modelling should give some insight into the dynamical and chemical mechanisms at work during this period.