Stratospheric clouds and ozone depletion in the Arctic during January 1989

The role of stratospheric clouds in springtime polar ozone depletion has been recognized in the Antarctic but not, to date, in the Arctic. Measurements made from two instrumented balloons in January 1989 have been used to establish both the appearance of Arctic stratospheric clouds and the signature of the onset of O sub(3) depletion at or around the altitude of these clouds. Comparison of the O sub(3) profile in the region of the clouds with those obtained during the past three austral spring seasons at McMurdo Station in Antarctica suggests the beginning of O sub(3) depletion at a height of 22-26 km.