Accommodation coefficient of HOBr on deliquescent sodium bromide aerosol particles M. Wachsmuth1,2, H. W. Gäggeler1,2, R. von Glasow3,*, and M. Ammann1 1Paul Scherrer Institut, Laboratory for Radio- and Environmental Chemistry, Villigen, Switzerland 2Also at Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland 3Max-Planck-Institut für Chemie, Abt. Chemie der Atmosphäre, Mainz, Germany *Present address: Center for Atmospheric Sciences, Scripps Institution of Oceanography, University of California, San Diego, USA
Abstract. Uptake of HOBr on sea salt aerosol, sea salt brine or ice is believed to be a
key process providing a source of photolabile bromine (Br2) and sustaining
ozone depletion cycles in the Arctic troposphere. In the present study, uptake of HOBr on sodium bromide (NaBr) aerosol particles was investigated at
an extremely low HOBr concentration of 300 cm-3 using the short-lived
radioactive isotopes 83-86Br. Under these conditions, at maximum one
HOBr molecule was taken up per particle. The rate of uptake was clearly limited by the mass accommodation coefficient, which was calculated to be
0.6 ± 0.2. This value is a factor of 10 larger than estimates used in earlier models. The atmospheric implications are discussed using the box
model "MOCCA'', showing that the increase of the accommodation coefficient
of HOBr by a factor of 10 only slightly affects net ozone loss, but significantly increases chlorine release.
Citation: Wachsmuth, M., Gäggeler, H. W., von Glasow, R., and Ammann, M.: Accommodation coefficient of HOBr on deliquescent sodium bromide aerosol particles, Atmos. Chem. Phys., 2, 121-131, doi:10.5194/acp-2-121-2002, 2002.