THE TROPICAL SUBTROPICAL SEMIANNUAL OSCILLATION IN THE UPPER TROPOSPHERE

The tropical-subtropical semi-annual oscillation (TSSAO) of the zonal wind and temperature in the upper troposphere has been described by va n Loon and Jenne. Their description was based on analysis of 20 Southe rn Hemisphere (SH) radiosonde stations and on two SH climatological at lases. This note documents further the TSSAO's climatology and its' sp atial and temporal variability This is accomplished by (i) using more radiosonde stations, in which data records span longer time periods, a nd (ii) using analyses from the European Centre for Medium Range Weath er Forecasts for a spatially coherent picture.