CHLORINE CHEMISTRY AND THE POTENTIAL FOR OZONE DEPLETION IN THE ARCTIC STRATOSPHERE IN THE WINTER OF 1991 92/

We present an analysis of chlorine chemistry in die Arctic stratospher e during the winter of 1991/92 and assess its potential implications f or ozone depletion. In accordance with observations of total organic c hlorine, ClONO2 and HCl, box model results indicate the following: (1) An almost complete activation of chlorine during the cold winter peri od. (2) A possible contribution from the heterogeneous reaction HOCl HCl and the gas-phase reaction CH3O2 + ClO to the complete conversion of HCl to active chlorine. (3) A strong buildup of ClONO2 following P SC disappearance which remains the main chlorine reservoir for about a month, after which HCl becomes dominant. (4) Appreciable chemical ozo ne loss in the lower stratosphere inside the polar vortex is conceivab le for the winter of 1991/92.