Correlation between the latitudinal profile of the Be air concentration and the Hadley cell extent in the Southern Hemisphere.

The cosmogenic radionuclide Be is one of the best tracers for aerosol transport since its half-life of 53 days is in the time scale of many atmospheric circulation phenomena. In this work, we analyze a 12-years-long daily time-series for the airborne Be concentration for nine air filtering stations in the Southern Hemisphere or close to it. The observed latitudinal distribution of Be concentration, with its maximum at the southern subtropical high-pressure belt, is similar to the one in the Northern Hemisphere. A good time correlation was found between the 7°-shift of the Be concentration latitudinal distribution and the seasonal displacement of the extent of the Hadley cell. This is consistent with tropopause folding events, mostly occurring in spring, being the main contribution for the injection of stratospheric Be into the descending branch of the Hadley cell.