HALOE ANTARCTIC OBSERVATIONS IN THE SPRING OF 1991

HALOE observations of O3, CH4, HF, H2O, NO, NO2, and HCl collected dur ing the October 1991 Antarctic spring period are reported. The data sh ow a constant CH4 mixing ratio of about 0.25 ppmv for the altitude ran ge from 65 km down to about 25 km at the position of minimum wind spee d in the vortex: i.e., the vortex center. and depressions in pressure versus longitude contours of NO, NO2, HF, and HCl in this same region. Water vapor, HF, and HCl enhancement are also observed in the vortex center region above approximately 25 km. Between 10 and 20 km, the exp ected mixing ratio signatures exist within the vortex, i.e., low ozone and dehydration. The water vapor increased by 50%, and the ozone leve l doubled in the vortex between October 11 and 24 in the 15 to 20 km l ayer. These changes imply a time constant for recovery from ozone hole conditions of 19 and 30 days for O3 and H2O, respectively. The data f urther show the presence of air inside the vortex between 3 and 30 mb which has mixing ratios characteristic of mid latitudes.