Quantifying denitrification and its effect on ozone recovery

Upper Atmosphere Research Satellite observations indicate that extensive de nitrification without significant dehydration currently occurs only in the Antarctic during mid to late June. The fact that denitrification occurs in a relatively warm month in the Antarctic raises concern about the likelihoo d of its occurrence and associated effects on ozone recovery in a colder an d possibly more humid future Arctic lower stratosphere. Polar stratospheric cloud lifetimes required for Arctic denitrification to occur in the future are presented and contrasted against the current Antarctic cloud lifetimes . Model calculations show that widespread severe denitrification could enha nce future Arctic ozone loss by up to 30%.