Ozone profile measurements within, at the edge of, and outside the Antarctic polar vortex in the spring of 1988

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Abstract
Ozone and temperature were measured during 38 balloon soundings at McMurdo Station, Antarctica (78° S), in the spring of 1988. Because of the motion of the Antarctic polar vortex, measurements were obtained within, at the edge of, and outside the vortex. Although the polar vortex did not remain over McMurdo as it did in 1986 and 1987, it was overhead long enough to establish that ozone depletion was less extensive and ended earlier than in either 1986 or 1987. In the vortex the ozone mixing ratio at 18 km decayed with an exponential half‐life of 29 days compared to 25 and 12 days in 1986 and 1987. While ozone partial pressure in the 16–18 km layer decayed to values as low as 10 nbar in 1986 and 3 nbar in 1987, ozone partial pressure dropped to only 60–70 nbar in 1988 in the depleted region, a reduction of 30 to 50%. Even with these differences in degree of ozone depletion there were similarities to previous measurements. Ozone depletion was caused by a sink between 12 and 20 km, and primary depletion was episodic, occurring in periods of <10 days. Measurements at the edge of the vortex displayed the ozone layering observed in 1986 and 1987 and suggest the exchange of ozone rich and poor air across the vortex wall in the 12–20 km layer. Outside the vortex, vertical profiles displayed a region of high ozone and constant temperature above 20 km.