Stratosphere-troposphere exchange as an ozone source to planetary boundary layer

Stratosphere-troposphere exchange (STE) events were identified over southern Brazil acting as a stratospheric ozone source to the Planetary Boundary Layer (PBL) during 2011-2013 period. There were 13 events with direct influence between 29° and 31° S (center of Rio Grande do Sul), with increase in ozone total column. In these cases, 4 occurred in 2011, 5 in 2012 and 4 in 2013. They were divided: in relation to the exchange latitude, the upper-level Jet Stream act, altitude of source and arrive of air parcels. The air parcels cross the tropopause between 120 and 320 hPa (dynamic tropopause), entering troposphere until the lower troposphere. Most cases (30,8%) reached 1000 hPa and the rest between 600 and 900 hPa. Just in one day the STE occurred in a lower latitude than 29° S; in all the other days (92,3%), STEs occurred in higher latitudes than 31° S (the closer it gets to the pole, the bigger is the ozone concentration, except in Ozone Hole Influence events) or between 29° and 31° S. In most cases (61,5%) it was observed STE along with the Jet Streak act.