Monday, 10 January 2005
Insights into Free Tropospheric Ozone Sources and Transport in July-August 2004 from IONS Soundings
During the multi-platform (ship, ground-based, satellite, aircraft) ICARTT (International Consortium on Atmospheric Research on Tranpsort and Transformation) set of experiments in July-August 2004, coordinated North American ozone soundings were made from Trinidad Head, California, nine stations east of the Rockies and from the ship R/V Ronald H Brown operating in the Gulf of Maine. The ozonesonde project is called IONS (INTEX [Inter- continental Transport Experiment] Ozonesonde Network Study). At most sites, launches were 3-7 times/week during midday to capture overpasses of sun-synchronous satellites. Based on forecast trajectories of selected ozone layers, features were selected for aircraft sampling. In general, soundings show: --> High pollution situations in the boundary layer over a few sites [Houston, occasionally Huntsville (AL) and Beltsville (MD)] --> Lower pollution conditions at most other sites --> Persistent mid- and upper tropospheric pollution in the northeastern and maritime stations. Pollution layers were often interspersed with air of stratospheric influence. Examples of these situations will be given along with some estimate of ozone imported and/or exported from several key regions. Graphical presentations of preliminary soundings can be viewed at: http://croc.gsfc.nasa.gov/intex/intex_ozonesondes.