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FY-1997 was a very busy year for ACD staff. A major field campaign (EXPRESSO) conducted in the Central African Republic and in the Congo, initiated and organized by ACD jointly with CNRS in France, was successfully completed. The purpose of the project was to better characterize and quantify biogenic emissions from the savanna and the tropical forest and their role in the formation of photochemical oxidants. Biosphere-atmosphere fluxes of trace gases were also measured in western US forests as part of the North American Research Strategy on Tropospheric Ozone (NARSTO). ACD staff participated in several other field campaigns including the POLARIS mission organized by NASA to examine chemical and dynamical processes in the Arctic stratosphere, and the NOAA-led North Atlantic Regional Experiment (NARE) to assess the export of tropospheric ozone and its chemical precursors from the North American continent to the Atlantic Ocean.
During the past year, however, emphasis was deliberately placed on the analysis of data collected during previous field campaigns (including the Aerosol Characterization Experiment (ACE-1); the NASA's DC-8 SUCCESS project; the NASA TOTE/VOTE field campaign; the NCAR-led STERAO-A campaign; the PEM-tropics mission; the SOS Formaldehyde Intercomparison Study, etc.). Several exciting results, obtained during these field projects, are highlighted in the following sections of this Annual Scientific Report.
Other accomplishments by ACD staff and visitors include the development of new state-of-the-art instrumentation: for example, an automatic spectrometer is providing high resolution infrared observations from Thule, Greenland, as part of the Network for Detection of Stratospheric Change (NDSC); a tunable diode laser (to measure CO and N2O), as well as a four-channel instrument (to measure nitrogen oxides and ozone) were developed to fly on high altitude aircraft (NSF/NCAR WB57). The development of an instrument for the measurement of acetone using chemical ionization mass spectrometry has also been initiated. At the same time, the modeling group has completed the development of global and regional chemical transport models, which will be very useful for the interpretation of field measurements.
ACD continues to put emphasis on laboratory kinetics. The focus in 1997 has been on the analysis on oxidation mechanisms for several organic compounds, and on the characterization of several heterogeneous reactions. As a service to the community and as a contribution to the International Global Atmospheric Chemistry (IGAC) Project, ACD is leading a series a planned laboratory experiments to evaluate current analytical methods used to measure hydrocarbons in the atmosphere.
As part of the NASA Earth Observation System, ACD is contributing to the development of a Canadian space-borne instrument (MOPITT) aimed at measuring carbon monoxide and methane in the troposphere. This instrument is expected to be launched on the AM-1 satellite in mid-1998. ACD staff is developing retrieval algorithms, as well as an airborne version of MOPITT. ACD staff are also directly involved in the design of the HIRDLS instrument aimed at measuring from space various chemical compounds in the stratosphere and upper troposphere.
Finally, during 1997, a large planning effort has been performed by the Division. A three-day retreat as well as several related planning meetings took place, and led to the completion of a strategic and an implementation plan for the next five years. The role of junior scientists in future ACD activities has been emphasized, and several activities are being planned under their leadership and responsibility.
Guy Brasseur
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