Abstract

The CMIP5 climate models simulate a robust poleward shift and strengthening of the main eddy-driven belt of Southern Hemisphere (SH) mid-latitude near-surface westerly winds (hereinafter referred to as the ‘westerly jet’ or ‘jet’) in response to future scenarios of increased greenhouse gas concentrations. Such changes have wide-reaching implications both regionally and globally relating to impacts on, for example, uptake of thermal energy and CO2 in the Southern Ocean and ice-ocean interactions around Antarctica. However, there is a larger inter-model spread in the magnitude of jet responses.

In this talk, recent and current research on explaining the CMIP5 diversity in projected 21st century westerly jet responses will be discussed. New results will be shown that emphasise the importance of understanding the role of coupled atmosphere/ocean/seaice interactions as a major driver of diversity in jet projections and that a large proportion of this diversity is correlated with interacting baseline biases in the atmosphere, ocean and sea ice. Implication for the potential to observationally constrain long-term multi-model projections of the westerly jet will be discussed.