Events in Physics
Oliver Allanson (Exeter): The importance of nonlinear physics in radiation belt modelling
The Earth's Outer Radiation Belt is a dynamic relativistic plasma population that is geomagnetically trapped in near-Earth space - the inner magnetosphere. This population is very challenging to model, with dynamics evolving on - and determined by - spatial and temporal scales that range from milliseconds to days, and gyroradii to Earth radii. Aside from being a very interesting and challenging physics problem, accurate modelling and prediction is important for safeguarding the operational satellites in orbit that underpin modern society. There is therefore a growing interest in operational space weather forecasts, such as those based on the model developed at the British Antarctic Survey (BAS-RBM), and now being incorporated into the UK MET Office Space Weather suite.
‘Non-adiabatic’ transport and acceleration of radiation belt particles is largely determined by resonant interactions with electromagnetic waves. Existing radiation belt modelling overwhelmingly relies upon 'quasilinear' techniques that essentially treat electromagnetic waves as having very small amplitudes. However, recent satellite datasets have demonstrated the prevalence of large amplitude (aka 'nonlinear’) electromagnetic waves. These effects have not yet been quantified or implemented on operational modelling scales. Understanding the impact of nonlinear waves on radiation belt particle populations is therefore an important question - and we hope to try and find some answers! In this talk I will give some review, and discuss recent and planned work.