HR: 10:50h
AN: A12A-03 INVITED     [Abstracts]
TI: Mixing in the Extratropical Tropopause Region: Observations and Modeling
AU: * Pan, L
EM: liwen@ucar.edu
AF: National Center for Atmospheric Research, 1850 Table Mesa Drive, Boulder, CO 80305 United States
AU: Konopka, P
EM: P.Konopka@fz-juelich.de
AF: Institute for Stratospheric Chemistry ICG-I, Research Center Jlich, Forschungszentrum Juelich, ICG-I, Jlich, D-52425 Germany
AU: Bowman, K P
EM: k-bowman@tamu.edu
AF: Texas A&M University, 3150 TAMU, College Station, TX 77843-3150 United States
AU: Browell, E V
EM: Edward.V.Browell@nasa.gov
AF: NASA Langley Research Center, Mail Stop-401A, 21 Langley Blvd, Hampton,, VA 23681-2199 United States
AU: McKenna, D
EM: danny@ucar.edu
AF: National Center for Atmospheric Research, 1850 Table Mesa Drive, Boulder, CO 80305 United States
AB: Stratosphere-troposphere exchange (STE) in the extratropics is a key factor that controls the chemical composition of the upper troposphere and lower stratosphere. Improving our ability to quantify STE is an important step for forecasting future change in chemical forcing to the climate change. To better understand the controlling mechanisms of STE in the extratropics, we investigate the role of dynamical processes at various scales in producing exchange and mixing. In particular, we focus on the transport characteristics in the region of the subtropical jet. While the jet core exhibits a barrier to isentropic mixing, the synoptic scale and mesoscale dynamics in the region surrounding the jet, in conjunction with large-scale wave breaking, produce irreversible exchange. As an initial step, we investigate the transport and mixing driven by large-scale winds, using both models and observations. Airborne observations from LIDAR and in situ tracers are used to identify the region of irreversible STE. A 3-D trajectory model is used to diagnose the region of mixing due to large-scale wind shear. A Lagrangian CTM (CLaMS) is used to investigate the aggregated effect of the wind shear to mixing of the stratospheric and tropospheric air. The results show that by computing the Lagrangian deformation of the atmospheric flow, it is possible to identify regions where mixing is occurring and to map out volumes of fluids exchanged in the mixing process. Potential contributions of turbulence and gravity wave breaking will be discussed.
DE: 3334 Middle atmosphere dynamics (0341, 0342)
DE: 3362 Stratosphere/troposphere interactions
DE: 3300 METEOROLOGY AND ATMOSPHERIC DYNAMICS
DE: 0341 Middle atmosphere--constituent transport and chemistry (3334)
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting