Haloe Antarctic observations in the spring of 1991

Abstract

HALOE observations of O₃, CH₄, HF, H₂O, NO, NO₂, and HCℓ collected during the October 1991 Antarctic spring period are reported. The data show a constant CH₄ mixing ratio of about 0.25 ppmv for the altitude range from 65 km down to about 25 km at the position of minimum wind speed 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 ∼25 km. Between 10 and 20 km, the expected mixing ratio signatures exist within the vortex, i.e., low ozone and dehydration. The water vapor increased by 50%, and the ozone level doubled inside the vortex between October 11 and 24 in the 15 to 20 km layer. These changes imply a time constant for recovery from ozone hole conditions or 19 and 30 days for O₃ and H₂O, respectively. The data further show the presence of air inside the vortex between 3 and 30 mb which has mixing ratios characteristic of mid latitudes.