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GTE Field Missions
| CITE |
Our understanding of tropospheric chemistry is limited primarily by our ability to accurately measure minute quantities of key tropospheric species. An initial, and continuing, focus of the GTE has been the development, testing, and evaluation of techniques capable of airborne measurements of trace species. The CITE-1 mission, consisting of a ground- based intercomparison, and two separate airborne campaigns to evaluate instrumentation for measuring carbon monoxide, nitric oxide, and the hydroxyl radical . The CITE- 2 mission focused on intercomparison of techniques for measuring nitrogen dioxide, nitric acid , and peroxyacetylnitrate, as well as a reevaluation of nitric oxide techniques. The CITE-3 mission focused on intercomparison of techniques to measure sulfur dioxide, dimethylsulfide, hydrogen sulfide, carbonyl sulfide, and carbon disulfide. |
| ABLE |
Nowhere is atmosphere-biosphere interactions more pronounced that within the atmospheric boundary layer-the lowest few hundred meters on the atmosphere. The ABLE missions have been designed to study emissions of gases from the biosphere, and the chemical changes that occur as these gases are transported through the boundary layer and into the free troposphere. Expeditions have now been completed in three ecosystems that are known to exert a major influence over global tropospheric chemistry and that are being profoundly affected by natural and human activities. These are ABLE-1 in the tropical Atlantic ocean; ABLE-2 in the Amazon Rain Forest; and ABLE-3 in the wetland/tundra of the North American Continent. |
| PEM-WEST and PEM-TROPICS |
Along the north western rim of the Pacific are the most populated countries of the world. The potential for these countries to emerge as major industrial centers, with the concurrent pollution is just beginning to be recognized. The PEM's were initiated to provide an early assessment of the chemistry over the Pacific ocean, and to study the impact of emissions from Asia on the Pacific region. The PEM-West expedition, focussed on the north western pacific region, conducted phase-A during a period of minimum outflow from Asia, while phase-B was conducted during enhanced outflow. The PEM-Tropics has focussed on the south tropical Pacific Basin, most of which is remote from continental regions. |
| TRACE |
TRACE-A was deployed in August 1992 to determine the cause and source of high concentrations of ozone that accumulate over the Atlantic ocean between southern Africa and South America during the months of August through October. The enhanced levels of ozone were observed to be the highest during the southern hemisphere's springtime, a period of intense burning of vegetation in both southern Africa and South America. The TRACE-A results showed the link between the biomass burning and the ozone pollution. TRACE-P, conducted in March/April 2001, had as it's major objectives to 1) determine the chemical composition of the Asian outflow over the western Pacific in spring in order to understand and quantify the export of chemically and radiatively important gases and aerosols, and their precursors, from the Asian continent and to 2) determine the chemical evolution of the Asian outflow over the western Pacific in spring and to understand the ensemble of processes that control the evolution. |
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