ARCTIC OZONE DEPLETION OBSERVED BY UARS MLS DURING THE 1994-95 WINTER

During the unusually cold 1994-95 Arctic winter the Microwave Limb Sou nder observed enhanced chlorine monoxide (ClO) in late Dec and through out Feb and early Mar. Late Dec ClO was higher than during any of the previous 3 years, consistent with the colder early winter. Between lat e Dec 1994 and early Feb 1995, 465 K (similar to 50 hPa) vortex-averag ed ozone (O-3) decreased by similar to 15%, with local decreases of si milar to 30%; additional local decreases of similar to 5% were seen be tween early Feb and early Mar. Transport calculations indicate that vo rtex-averaged chemical loss between late Dec and early Feb was similar to 20% at 465 K, with similar to 1/4 of that masked by downward trans port of O-3. This Arctic chemical O-3 loss is not readily detectable i n MLS column O-3 data.