PROFILE OBSERVATIONS OF LONG-LIVED TRACE GASES IN THE ARCTIC VORTEX

Five sets of vertical profiles of long-lived trace gases were measured in the stratosphere at high northern latitudes (68-degrees-N) during three field campaigns of the CHEOPS - Project. Large whole air samples were collected by means of balloon-borne cryogenic samplers analysed for their content of N2O, CH4, CFCl3, CF2Cl2, C2F3Cl3, CCl4, CH3Cl and CH3CCl3. The measured polar profiles will be compared with mean vertical distributions derived from a series of observations at midlatitudes (44-degrees-N). The difference indicates a pronounced effect of subsidence in the Arctic winter stratosphere with a net downward shift of the Arctic vertical profile by about 7 km over the time period from November until February. Owing to this efficient downward transport, the abundance of chlorine in the form of reservoir and reactive species, is increased in the lower Arctic stratosphere to about twice that observed at midlatitudes.