There remain significant uncertainties in understanding the changes in atmospheric chemical and physical processes affecting ozone and other constituents in the upper troposphere and lower stratosphere (UT/LS), the first few kilometers above and below the tropopause. A series of analyses using satellite and aircraft measurements, in combination with modeling tools, to better understand the processes affecting atmospheric composition and transport processes in the upper troposphere and lower stratosphere. The primary focus of these calculations is to evaluate the correlation of the stratospheric abundance of N2O, O3, NOy, H2O and CH4 in the UT/LS using the new fully coupled troposphere, stratosphere and mesosphere version of the three-dimensional global scale chemical-transport model, MOZART 3 (Model for OZone And other Related Tracers, version 3). The extratropics is of particular interest as more measurements available in this region. Studies will be particularly aimed at testing, evaluating and interpretation of recent measurements made by SAGE III, HALOE and other satellite instruments and by observations made from various aircraft campaigns, ozonesondes, and balloon experiments.

The objective of this study is to use MOZART-3 in studies to understand the relative roles of chemistry and transport in determining the budget of ozone and other constituents in the UT/LS region. Our intention is to have as comprehensive as possible and systematic analysis of the UT/LS region. As a result we expect to: a) Analyze the distributions of N2O, ozone, NOy, and CH4 between UT and LS in different seasons and compare those with available field datasets. Measurement validation analyses through comparison of datasets with current theoretical understanding of atmospheric processes as represented in the models. b) Analyze seasonal variation of correlations between various gases, such as N2O and O3, N2O and CH4, or N2O and NOy. c) Evaluate the mixing strength of potential transport barrier in the UT/LS for the mid-latitudes. An important question is how much of stratosphere-troposphere exchange in the mid-latitude to cause the species distribution?