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 stratosphere during the winter of 1991/92 and assess its potential implications for ozone depletion. In accordance with observations of total organic chlorine, ClONO2 and HCl, box model results indicate the following: (1) An almost complete activation of chlorine during the cold winter period. (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 PSC disappearance which remains the main chlorine reservoir for about a month, after which HCl becomes dominant. (4) Appreciable chemical ozone loss in the lower stratosphere inside the polar vortex is conceivable for the winter of 1991/92.