Oral Presentation AMOS Annual Meeting and International Conference on Tropical Meteorology and Oceanography

Understanding the relationship of ENSO and SAM in the present and future climate (#168)

Eun-Pa Lim 1 , Pandora Hope 1 , harry hendon 1
  1. BoM, Docklands, VICTORIA, Australia

El Nino-Southern Oscillation (ENSO) is a key source of predictability of global climate on seasonal-interannual time scales. While some regions are influenced by ENSO directly, for most other regions the influence is via teleconnections. The most widely known teleconnections of ENSO are via equivalent barotropic Rossby wave propagation originating from the equatorial Pacific, namely, the Pacific-North American Pattern/Pacific-South American Patterns. ENSO can also drive zonally symmetric teleconnections via variations in the annular modes. In the Southern Hemisphere, ENSO is significantly linked to the Southern Annular Mode (SAM) in austral spring to summer. These interactions can enhance the influence of these climate drivers on Australia's climate extremes. The majority of CMIP5 models struggle to simulate this interaction of ENSO with the SAM, which leaves a great deal of uncertainty in understanding future changes in climate extremes over Australia that can arrive from symbiotic occurrences of ENSO and extremes of the SAM. To improve our understanding of the interaction of ENSO and the SAM in the present and a future climate projected with increasing CO2, we have conducted dynamical coupled model experiments using POAMA for three strong canonical eastern Pacific El Nino events of 1982, 1997 and 2015 with ocean temperature trends projected to a warmer future with increasing CO2. In the presentation, we show how the negative polarity of the SAM associated with strong eastern Pacific El Nino in the present climate may change in response to the warming of the mean sea surface.