The collaborative field experiment, Stratosphere-Troposphere Analyses of Regional Transport (START08), will study the chemical and transport characteristics of the extratropical upper tropospheric and lower stratospheric (ExUTLS) region. The experiment, which will take place during the Spring 2008 time period, utilizes the NSF/NCAR High-performance Instrumented Airborne Platform for Environmental Research (HIAPER) which has the range, endurance, and altitude ceiling necessary to conduct the research. The objective of the experiment is to use in situ chemical, microphysical, and dynamical measurements, satellite data, and models to better understand the multi-scale dynamical processes that control the chemical composition and microphysics of the ExUTLS. In particular, the investigation will focus on the behavior of the extratropical tropopause as a transport boundary and on key chemical transport pathways and the related dynamical processes. These processes include breaking of Rossby waves, the growth and decay of synoptic-scale waves, tropopause folds and warm conveyor belts, the development of frontal systems, initiation and breaking of gravity waves, and deep convection. In addition, these processes control the formation and evolution of the ice cloud layers in the ExUTLS. This field study will use tracer-tracer correlations as a diagnostic tool for transport in the UTLS region. The results of the experiment will include a set of diagnostics of chemical transitions between the UT and LS, an estimate of the lifetime of the air mass in the extra-tropical transition layer, and tracer characterizations of major transport processes that couple the UT and LS and which determine the structure and chemical composition of the UTLS. A small suite of microphysical probes will quantify the ice mass and water content of clouds in the UT/LS. With the enhanced measurement capability and platform compared to some earlier studies, START08 will provide more insight into the behavior of tracers and their relationships under the influence of targeted dynamical processes, and expand the database for establishing a theoretical framework for testing models.
The project supports the development of community research capabilities in significant ways. START08 will train graduate students and post-doctoral scientists in both instrumental/analytical atmospheric chemistry and data analysis done collaboratively with modelers and other science team members. Research from the START08 project will be used to enhance current graduate education classes in atmospheric science. Additional educational outreach is planned that includes interaction with ongoing programs (e.g., National Ocean Science Bowl, and Project IMPACT).