Satellite image analysis in support of atmospheric chemistry campaigns: Examples of Unidata's impact on interdisciplinary graduate research and education

The University of Virginia has participated in a number of research programs focussed on identifying the origin and fate of ozone in the non-urban troposphere, and its transport on a hemispheric scale. Our ability to forecast and diagnose the significant contribution of natural ozone has improved with our use of multispectral satellite imagery along with derived dynamical tracers. In particular, we have used the analytic expression relating GOES-8/9 water vapor radiances to relative humidity in combination with regional-scale model temperature grids to derive relatively high horizontal resolution (8km) images of upper-tropospheric specific humidity. The accuracy of these images increases with dryness of the atmosphere; consequently, the images provide new insight into the dynamics of events such as tropopause folds, cut-off lows, and shear lines. Using in-situ chemical observations from recent field campaigns, we will show that in the wake of stratosphere/troposphere exchange events, the distribution of dry air in the mid-to-upper troposphere is an effective tracer for ozone of stratospheric origin. The availability of Unidata internet data feeds and supported applications have enabled the development of this research and have fostered interdisciplinary education on tropospheric dynamics as they impact chemistry. In addition to the traditional GOES data available to the Unidata community, we have recently expanded our ability to interpret variations in ozone by importing into McIDAS gridded fields of total column ozone from the Total Ozone Mapping Spectrometer (TOMS) on the polar orbiting NASA Earth Probe. We use this information as an independent corroboration of our interpretation of the dynamically driven variations in the tropospheric ozone.

Previous atmospheric chemistry investigations relied upon trajectory models, and modelled tracers, such as isentropic potential vorticity as primary tools for diagnosing Lagrangian transport and airparcel origin of balloon and aircraft data. Our ability to visualize atmospheric flow and the evolution of tracer fields like specific humidity provides a context for evaluating traditional diagnostic tools like Lagrangian trajectory models, and regional-scale chemical transport models. Results to date show promise for advancing our understanding of the global oxidant budget.