The 2008 Stratosphere-Troposphere Analyses of Regional Transport (START08) experiment

Investigation of chemical, dynamical, and microphysical processes occurring in the extratropical upper troposphere (UT) and lower stratosphere (LS) (the ExUTLS), the altitude region from ~5 to 15 km, is crucial for understanding long term global climate change and tropospheric air quality. It is a region where ozone is an effective greenhouse gas, and where water vapor, cirrus clouds, and aerosols have a strong influence not only on the atmospheric radiation budget, but also on chemical budgets. The ExUTLS is also a region where transport processes that couple the stratosphere and troposphere occur on a multitude of space and time scales. These transport processes, combined with the strong vertical gradients in many chemical constituents, present a challenge to observational techniques and numerical models.

The overall objective of the recently completed START08 experiment was to use in situ chemical, microphysical, and dynamical measurements, satellite data, and models to better understand the dynamical processes that control the chemical composition and microphysics of the ExUTLS. The START08 campaign was conducted during 2 intensive periods from mid-April to mid-May and from mid to late June, 2008. Airborne measurements were taken from the NSF HIAPER aircraft, which covered an altitude range up to approximately 14 km. In situ measurements of a wide range of trace gases, water vapor, aerosol properties, and vertical temperature structure were obtained under targeted dynamical conditions to better understand transport and mixing regimes in the area of the ExUTLS. Model analyses and satellite retrievals were used to direct the aircraft to appropriate regions.

This presentation will present an overview of the experiment and will highlight some initial results with examples of measurements and correlations that address START08 science objectives.