Séminaire
Global ocean sea surface temperature (SST) exhibits significant year-to-year variability, with important implications for regional atmospheric circulation.
Like air temperature, the upper ocean has warmed significantly over the past century in a non-uniform way. Southern Hemisphere climate and rainfall variability is fundamentally controlled by ocean SST variations, primarily those associated with the El Niño / Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD). Significant rainfall variability is also associated with the Southern Annular Mode (SAM), a large-scale pressure oscillation between the Antarctic and mid-latitudes.
The SAM has exhibited a significant trend in recent decades, projected to continue over the next 50 years. The SST in the tropical Pacific and Indian Oceans is also changing and this could imply long-term trends in the behaviour of ENSO and the IOD. In this presentation I will overview the major drivers of Southern Hemisphere rainfall variability and their associated predictability. I will also outline how these natural modes are changing and what the implications are for regional climate.