Essential characteristics of the Antarctic-spring ozone decline: Update to1998

Using both ground-based and satellite data up to December 1998, the intensi ty, duration, appearance at both horizontal and vertical scales and ozone-m ass deficiency (O3MD) of the severe ozone decline observed over the souther n polar region are presented. Over the last six years: the depletion within the ozone hole area (i.e. total ozone amounts <220 m atm-cm) is almost thr ee times more severe than in the early 1980s, the ozone hole (O(3)h) area h as exceeded 22 million km(2) at its maximum, and the lowest total ozone was similar to 100 m atm-cm. However, during the 1998 season for the first tim e for nearly 20 days the O(3)h area exceeded 25 million km(2), and the inte grated O3MD during September-October, poleward of 60 degrees S, exceeded th e average value of the 1990s by similar to 25%. At the beginning of the 198 0s, ozone hole values were observed mostly in October, but more recently, t hey frequently continue until mid-December. The depletion was most severe i n the 12-20 km layer over Antarctica: similar to 70% in September, similar to 90% in October and similar to 80% in November. Related to this, the mont hly mean lower stratospheric temperatures between 70-90 degrees S have decl ined by similar to 10 degrees C in October. similar to 12 degrees C in Nove mber and by similar to 5 degrees C in December. Tailing the last six years seasonally integrated O3MD over the area poleward of 60 degrees S (average similar to 6,300 Mt) is about a third greater than the O3MD over the northe rn polar region winter-springs. Over the southern mid-latitudes O3MD is abo ut a third less than the deficiency observed between 35-55 degrees N.