HR: 0800h
AN: A21B-0730    [Abstracts]
TI: Resonance Fluorescence Instrument for the {\it in Situ} Detection of BrO in the Atmosphere: Instrument Description, Calibration, and Flight Data Analysis
AU: * Wilmouth, D M
EM: wilmouth@huarp.harvard.edu
AF: Harvard University, Department of Chemistry and Chemical Biology, Cambridge, MA 02138 United States
AU: Stimpfle, R M
EM: stimpfle@huarp.harvard.edu
AF: Harvard University, Department of Chemistry and Chemical Biology, Cambridge, MA 02138 United States
AU: Anderson, J G
EM: anderson@huarp.harvard.edu
AF: Harvard University, Department of Chemistry and Chemical Biology, Cambridge, MA 02138 United States
AB: Losses of ozone over midlatitudes of the northern hemisphere are well documented in both the scientific literature and the public policy arena. Accurately defining secular trends in the distribution of ozone and establishing the mechanisms responsible for the observed losses are two dominant and enduring issues. The latest WMO report, {\it Scientific Assessment of Ozone Depletion: 2002}, states: ``The vertical, latitudinal, and seasonal characteristics of changes in midlatitude ozone are broadly consistent with the understanding that halogens are the primary cause of these changes, in line with similar conclusions from the 1998 Assessment.'' Other studies, however, have indicated alternative explanations to midlatitude ozone loss. Therefore, given the continued uncertainty, it is prudent to examine the full complement of halogen radical families in the lower stratosphere from the tropics to midlatitudes. Accurate BrO measurements, in particular, are critical due to the high efficiency of bromine compounds at ozone destruction. However, efforts to test the abundance and speciation of bromine in the stratosphere have been particularly hampered by low atmospheric concentrations. Here we present details of our redesigned resonance fluorescence axis for {\it in situ} BrO detection, which is incorporated into the Harvard Halogen flight instrument. These modifications provide the capability to detect BrO with greater sensitivity, precision, and spatial resolution than in any previous {\it in situ} aircraft measurement. Instrument calibrations have been ongoing, and details of this work, along with analysis of the BrO data from twelve flights of the SOLVE mission to Kiruna, Sweden, are presented. We estimate an accuracy of BrO measurements from the Harvard Halogen flight instrument of \pm20% (1$\sigma$) with a detection limit of 3 pptv in 5 minutes.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0317 Chemical kinetic and photochemical properties
DE: 0340 Middle atmosphere--composition and chemistry
DE: 0341 Middle atmosphere--constituent transport and chemistry (3334)
DE: 0394 Instruments and techniques
SC: Atmospheric Sciences [A]
MN: 2004 AGU Fall Meeting