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The predictability of tropical Pacific decadal variability: Insights from attractor reconstruction
4 March 2020 @ 2:00 pm - 3:00 pm
Nandini Ramesh (University of California)
The decadal-interdecadal variability of the tropical Pacific region has been shown to have wide-ranging impacts on hydroclimate on multiple continents, the rate of global mean sea surface temperature rise, and marine ecosystems. However, the small number of interdecadal shifts that have occurred during the observed period poses a significant challenge to developing an understanding of the mechanisms that drive this variability and whether it is potentially predictable.
In this study, we make use of a 100,000-year unforced simulation from an intermediate-complexity model of the tropical Pacific region in order to examine the predictability of this phenomenon. Using an attractor-reconstruction scheme, we find that the interdecadal regimes of this system emerge as a pair of orbits in a three-dimensional state space. The system is found to spend up to 37% of the time in highly-predictable regions of the state space, implying that the system is frequently in states from which high-confidence forecasts can be made. We also conduct a comparison with the short time series available from observations and GCM simulations and find that the observations show significant similarities to the intermediate-complexity model.
Brief Biography: Nandini Ramesh is a postdoctoral scholar at the University of California, Berkeley. Her research focuses on tropical climate dynamics and climate prediction, particularly in the context of interannual to interdecadal climate variability. She received her PhD in Ocean and Climate Physics from Columbia University (USA) and also holds an M.Sc. in Earth Physics from the Australian National University and a B.Sc. in Physics from the University of Madras (India).