EVIDENCE FOR ARCTIC OZONE DEPLETION IN LATE FEBRUARY AND EARLY MARCH 1994

Significant chemical ozone (O-3) loss in the 1993-94 Arctic winter occ urred mainly during an unusually late cold spell of similar to 10 days in late Feb/early Mar. Over the 30 d period studied (including the co ld spell), observed vortex-averaged O-3 at 465 K (similar to 40 hPa) d ecreased by similar to 10. New three-dimensional, diabatic trajectory calculations show that this observed decrease represents only about ha lf of the net chemical. loss (similar to 20%) during the 30 day period . The resupply of lower stratospheric O-3 by transport in Feb 1994 was considerably greater than in 1993, when transport masked only about a quarter of the chemical loss in Feb/Mar. The net estimated chemical l oss over 30 days in 1994 was comparable to that over the same 30 days in 1993, but mainly occurred at a faster rate during the brief cold sp ell. These results highlight the impact of Arctic interannual variabil ity on the relative roles of chemistry and dynamics in O-3 evolution d uring recent Arctic winters.