The Spinning Earth

Saturday, October 6, 2001 - 9:00am - 9:40am
Lind 409
Raymond Hide (NONE)
Possibly the most striking feature of the long-term behaviour of the main geomagnetic field are the very long (~ 30 MYr) intervals when no polarity reversals seem to have occurred. Generic nonlinear processes in self exciting dynamos include the redistribution of kinetic energy by Lorentz forces. According to recent work on certain Faraday disk dynamos, under the simplest boundary conditions this process can give rise to nonlinear quenching of reversals, thereby providing a possible theoretical basis for interpreting superchrons and other features of the reversal timeseries. It is of general theoretical interest to study nonlinear quenching of fluctuating solutions of other autonomous sets of nonlinear ODE's, such as the Lorenz and Roessler sets.