Space Science Seminar: Wave generation in Earth's Radiation Belts: why is it important and how can we efficiently model it?

Dr. Clare Watt, Department of Meteorology, University of Reading

Thursday 15 May 2014, 1400-1500
Cavendish Colloquium Room

The acceleration, transport and loss of high-energy particles in Earth's Outer Radiation Belts is controlled largely by electromagnetic waves across a wide spectrum. Significant wave power results from plasma instabilities driven by unstable particle populations in the Outer Radiation Belts, e.g. temperature anisotropy. In this talk, I will present a new method to predict the wave spectra of whistler-mode waves that are driven unstable by temperature anisotropy in the dawn-noon sector. Traditionally, wave generation in space plasma is simulated using an initial value model, where nonlinear equations are stepped forward in time over a small volume. These initial-value simulations employ restrictive assumptions (e.g. parallel propagation) to render them computationally tractable, but still require vast computing resources to study just a few milliseconds of wave-particle interactions. The new wave generation model combines raytracing and the equations of radiation transfer to estimate wave spectra over a large volume, with no restrictions on the wave trajectories, providing a prediction of wave spectral characteristics controlled only by the ambient plasma and magnetic field properties.

The model I describe in this talk is part of a much larger effort to understand the physics of the Outer Radiation Belts and improve predictive models that are used in the operational forecasting of Space Weather.