The Role of Chlorine Chemistry in Antarctic Ozone Loss: Implications of New Kinetic Data

New kinetic data yielding a slower formation rate and larger absorption cross sections of C{ell}{sub 2}O{sub 2} are incorporated into a photochemical model to reassess the role of chlorine chemistry in accounting for the ozone reductions derived from TOMS observations in different regions of the Antarctic polar vortex during 1987. The model is further constrained by existing measurements from the Airborne Antarctic Ozone Experiment (AAOE) and the National Ozone Expedition (NOZE)-II. Calculated concentrations of C{ell}O based on the new kinetic data increase by almost a factor of two between the collar and core regions of the vortex during the second half of September. As a result of the higher concentrations of C{ell}O, the calculated ozone reductions in the vortex core appear to be still consistent with the TOMS observations in spite of the slower rate for the self-reaction of C{ell}O. The agreement in the collar region is poorer. However, uncertainties in mixing, possible spatial inhomogeneities in both C{ell}O and O{sub 3}, the lack of more extensive data, and the uncertainties in the rate data and observations preclude determination of whether additional processes are required to account for the observed ozone removal in the collar region.

[1]  W. Brune,et al.  In situ observations of BrO over Antarctica: ER‐2 aircraft results From 54°S to 72°S latitude , 1989 .

[2]  James G. Anderson,et al.  In situ observations of BrO over Antarctica: ER-2 aircraft results from 54 degree S to 72 degree S latitude , 1989 .

[3]  L. Heidt,et al.  Transport into the south polar vortex in early spring , 1989 .

[4]  C. B. Farmer,et al.  Infrared aircraft measurements of stratospheric composition over Antarctica during September 1987 , 1989 .

[5]  J. Hereford,et al.  Ozone profile measurements at McMurdo Station, Antarctica, during the spring of 1987 , 1989 .

[6]  C. B. Farmer,et al.  Nitrogen and chlorine species in the spring Antarctic stratosphere - Comparison of models with Airborne Antarctic Ozone Experiment observations , 1989 .

[7]  M. McCormick,et al.  Implications of AAOE observations for proposed chemical explanations of the seasonal and interannual behavior of Antarctic ozone , 1989 .

[8]  M. Coffey,et al.  Airborne measurements of stratospheric constituents over Antarctica in the Austral Spring, 1987: 2. Halogen and nitrogen trace gases , 1989 .

[9]  S. Sander,et al.  Rate of formation of the ClO dimer in the polar stratosphere: implications for ozone loss. , 1989, Science.

[10]  C. B. Farmer,et al.  Lagrangian photochemical modeling studies of the 1987 Antarctic spring vortex: 1. Comparison with AAOE observations , 1989 .

[11]  D. Toohey,et al.  Kinetics of O3 destruction by ClO and BrO within the Antarctic vortex: An analysis based on in situ ER‐2 data , 1989 .

[12]  L. Emmons,et al.  New observations of a large concentration of ClO in the springtime lower stratosphere over Antarctica and its implications for ozone-depleting chemistry , 1989 .

[13]  Adrian F. Tuck,et al.  Synoptic and chemical evolution of the Antarctic vortex in late winter and early spring, 1987 , 1989 .

[14]  R. A. Cox,et al.  Kinetics of the reaction ClO+ClO→products and its potential relevance to Antarctic ozone , 1986 .