GROUND-BASED MILLIMETER-WAVE OBSERVATIONS OF ARCTIC OZONE DEPLETION DURING WINTER AND SPRING OF 1996 97/

Ground based millimeter-wave measurements of Arctic stratospheric ozon e in the winter 1996/97 are presented. The measurements have been perf ormed at one of the primary Arctic stations of the Network for the Det ection of Stratospheric Change (NDSC) in Ny-Alesund, Spitsbergen (78.9 degrees N, 11.9 degrees E). Over the period 11 February to 26 April t he measurements show an ozone mixing ratio decrease of 1.3 ppm in the lower stratosphere. Correspondingly, stratospheric ozone column densit ies decreased by more than 50 DU. Taking into account the transport of ozone due to diabatic decent, we estimated chemical ozone loss rates of 22 ppb/day in February decreasing to 15 ppb/day in late April 1997.