The Development of a Fast-Respone, Lightweight Instrument for In Situ Measurements of Reactive Chlorine and Bromine in the Lower Stratosphere

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ATM-9313412 Toohey The concentration of ozone in the lower stratosphere is sensitive to interaction of part-per-trillion abundances of radical species in the NOx, HOx, ClOx, and BrOx families. While NOx and NOx and HOx are predominantly of natural origin, concentrations of the halogen oxides in the stratosphere are thought to be increasing due to anthropogenic uses of organic halides, mainly the chlorofluorocarbons (CFC's), halons, and methyl bromide. The inherant non-linear coupling of these radical families complicates interpretations of stratospheric photochemistry that rely either on isolated measurements of a single species in the atmosphere or on measurements using a single detection technique. This research project will focus on the design and deployment of a new instrument for in situ measurements of reactive chlorine (ClO and Cl2O2) and reactive bromine (BrO), one based on the technique of chemical-conversion resonance fluorescence and one which has flown successfully on aircraft and balloons. This instrument will be sufficiently lightweight that it could be deployed easily in conjunction with existing balloon- or aircraft- borne payloads, especially those to be flown on a new class of unmanned aircraft. Two major objectives will direct this project. First, these researchers will work closely with investigators who measure the halogen oxides with remote techniques from the ground, balloons, and space to provide a critical intercomparison of the available techniques and an evaluation of the uncertainties of the measurements over the altitude range from 12 to 35 km. They are also interested in interactions with those members of the Network for Detection of Stratospheric Change (NDSC) and of the Upper. Atmospheric Research Satellite (UARS). Second, the project scientists will seek collaborative investigations of the chemical and dynamical processes that determine the abundances of ozone- destroying radicals in the lower stratos phere. Their main interest will be the influence of aerosols on the balance of NOx, ClOx, and BrOx chemistries, especially near the tropical tropopause and at mid-latitudes. This instrument will be sufficiently lightweight that it could be deployed easily in conjunction with existing balloon- or payloads, especially those to be flown on a new class of unmanned aircraft.