From: Antony Clarke
Organization: University of Hawaii, Department of Oceanography

Research Area: CHEMISTRY

Mission Scenario: Chemical processes, aerosol and clouds

It is now well recognized that clouds act as a chemical factory in the atmosphere and play a muti-faceted role not only in the dynamic pumping and scavenging of species but also play a key role in heterogeneous chemistry linking many aerosol and gas phase species. Understanding the impact of both local and global cloud systems on atmospheric chemistry will necessarily involve well instrumented aircraft capable of measuring gases, aerosol, cloud and atmospheric properties over large spatial scales. The role of the InterTropical Convergence Zone (ITCZ) in modifying atmospheric chemistry on the scale of the Hadley circulation is of interest and would require such measurements at all altitudes in the troposphere and over extended remote regions. Such a program would require a suite of measurements. These would include a platform equipped with fast response meteorological sensors suitable for turbulence analysis, wing probes for ambient particle/cloudroplet analysis, inlets for fast mass spectrometers and instrumentation for selected gas phase species. Aerosol inlets including a CVI and various aerosol inboard instrumentation and samplers would also be needed.. Other instrumentation would include a lidar, radiometric instrumentation, SST, dropsondes, actinic flux etc.

An experiment mission might consist of flights both north and South of the ITCZ in tropical regions expected to be "pristine" and in regions subject to anthropogenic influence. A 10 hour flight might include a 3hr ferry to the study site and similar time to return. The flight would include vertical profiles and stacked low altitude legs of about 20+ minutes each could be carried out to characterize low level inflow and outflow characteristics. These might be at 300, 1000, 2000, 4000, 8000 ft and require up to 2 hours to complete without aircraft overheating. These would be followed by several higher altitude legs up to 50,000ft. to characterize various ITCZ outflow regions. Some in-cloud data would also be taken. Data from the vertical profiles could then be coupled to current meteorological information uploaded to the aircraft to select altitudes and directions to fly that would maximize opportunities to follow outflow regions spreading away from the ITCZ. Other flights would include efforts focussed on inflow, outflow and in-cloud characterization of individual clouds and cooperative missions with ship platforms.

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