On the Antarctic origin of low ozone events at the South American continent during the springs of 1993 and 1994

This paper reports the detection of several low total ozone events at mid-latitudes in the South American continent during the springs of 1993 and 1994. During these ozone depletions the total ozone column reached values as low as 150 Dobson Units at high latitudes (56S). It was found that the temperature of the lower stratosphere for the 450 K isentropic surface decreased with each low ozone event observed, suggesting that masses of ozone poor air were transported from the cold polar vortex to the South American continent. Isentropic back trajectory analyses corroborate the Antarctic origin of the observed low ozone events.