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Tuesday 22 Oct 2019A Mechanism of the Madden-Julian Oscillation and its Relation to Excitable Media

Prof. Geoff Vallis - University of Exeter

Harrison 103 13:30-15:30

The Madden-Julian Oscillation (MJO) is the most prominent feature of tropical variability on intra-seasonal timescales. It is characterized by band of precipitation across the equator that moves eastward at about 5 m/s. Although it was discovered some 40 years ago its mechanism has remained a mystery, and more that once has it been described as `the holy grail of atmospheric science'. In this seminar I will use the moist shallow water equations to construct a simple model of the MJO that transparently exposes a possible mechanism. In this concept, the MJO turns out to be an example of an `excitable dynamical system’, other examples being networks of neurons, cellular automata, chemical interactions in fluids and the Mexican wave.

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