Wednesday, 29 August 2007
3.PS-76
Observations of chlorine monoxide over Scott Base, Antarctica, during the ozone hole, 1996-2005
Brian J. Connor1, Philip Solomon2, James Barrett2, Thomas Mooney2, and Alan Parrish3. (1) NIWA, PB 50061, Omakau, 9352, New Zealand, (2) Stony Brook University, Stony Brook, NY 11794, (3) University of Massachusetts, Amherst, MA
We report observations of chlorine monoxide, ClO, in the lower stratosphere, made from Scott Base (77.85º S, 166.77º E) in springtime during each year, 1996-2005. The ClO amounts in the atmosphere are retrieved from remote measurements of microwave emission spectra. ClO column densities of up to about 2.5 x 1015 cm-2 are recorded during September. Maximum mixing ratios of ClO are approximately 2 ppbv. The annual average of ClO column density during late winter/early spring is anticorrelated with similar averages of ozone column measured at nearby Arrival Heights, with correlation coefficient of –0.81, and with averages of ozone mass integrated over the entire polar region, with similar correlation coefficients. There was a substantial decrease in ClO amounts during 2002-2004. There has been no systematic change in the timing of chlorine deactivation attributable to secular change in the Antarctic vortex.