STRAT
Beginning in May 1995, the NASA ER-2 has flown with instruments to investigate the movement of long-lived trace gases in the lower stratosphere and upper troposphere. By increasing our understanding of such motions, the Stratospheric Tracers of Atmospheric Transport (STRAT) experiment should increase our ability to determine whether certain gases in aircraft exhaust get into the prime ozone production region in the tropics. The STRAT flights are out of NASA Ames Research Center and Barbers Point Naval Air Station. STRAT deployments have been successfully staged in May 1995, October-November 1995, January-February 1996, July-August 1996, and September 1996. The final regular deployment of STRAT is scheduled to take place in December 1996. Objectives: 1. To define the rate of transport of trace gases (such as HSCT exhaust emissions) from the stratosphere to the troposphere, i.e., to determine the global burden that will result from continuous aircraft emissions into the stratosphere. This objective requires detailed measurements of tracer concentrations close to the tropopause, where tracer gradients are very steep. 2. To improve understanding of dynamical coupling and rates for transport of trace gases between tropical regions (where ozone formation is most rapid) and higher latitudes and lower altitudes (where most ozone resides). For example, we seek to define the quantity of exhaust entrained from mid-latitude source regions into the tropical upwelling zone, where it can be transported to critical altitudes (above 25 mbar) in the tropics. 3. To improve understanding of the chemistry in the upper troposphere and lower stratosphere. This will include the first concerted measurements of the coupled chemistry of odd hydrogen, odd nitrogen, and CO in the near-tropopause region. Understanding the partitioning of NOy in this region is poorly constrained and the lack of OH and HO2 measurements has hindered progress. These observations will address some of the key issues related to the influence of both a potential HSCT fleet as well as the existing subsonic fleet on ozone. 4. To provide data sets for testing two-dimensional (2-D) and three-dimensional (3-D) models used in assessments of impacts from stratospheric aviation, including meteorological data for application to data-assimilation models and globally-representative ensembles of tracer data. For more information, link to "http://cloud1.arc.nasa.gov/strat/index.html" or "http://code916.gsfc.nasa.gov/Public/Analysis/aircraft/strat/strat.html" [Summary provided by NASA]
S - U