The September 2002 Antarctic vortex major warming as observed by visible spectroscopy and ozone soundings

The record of O 3 total column and NO 2 obtained by visible spectroscopy at Ushuaia (55°S), Marambio (64°S) and Belgrano (78°S) and vertical ozone profiles from the latter station provide insight into the unprecedented major warming observed above Antarctica in the last week of September 2002. From 18 September to 25 September the temperature increased 54°C at the isentropic level of 700K. The temperature anomaly was observed down to the level of 300K in which a well‐defined tropopause was established. From comparison of the ozone profiles before and during the event, it can be seen that a fast increase in O 3 took place basically above 500K, but the layer where the ozone hole occurs was barely affected. Low potential vorticity values above Belgrano occurred only at levels above 500K, confirming that the vortex split was confined to heights above the layer of the Antarctic spring depletion. The signature of poleward‐transported air is clearly visible from the NO 2 column departure from the envelope of the previous years in all three stations. NO 2 columns larger than typical for ozone hole conditions by 400% were observed at Belgrano. Diurnal variations provide evidence of non‐denitrified extra‐vortex air.