Time：Oct 9（Wed）4:00 pm Where：N415 Physics Building Title：Toroidal and Poloidal Alfven Waves and Field Line Resonances
Abstract：In this presentation I shall briefly describe the characteristics of ultra low frequency (ULF) pulsations in Earth's magnetosphere, and consider how they are generated and filtered by the magnetosphere. I will review some Canadian ground-based observations of ULF waves as detected using all-sky cameras, meridian scanning photometers, HF-radar and magnetometers. An example of broad-band excitation of ULF waves in Earth's magnetosphere will be illustrated using observations from THEMIS, whch show agreement with models of the Alfven continuum. The concept of "magic frequencies" will be introduced along with a discussion of how quantized cavity mode field line resonances might be related to the onset of geomagnetic storms. The emphasis of the talk will then shift to a discussion of the influence of ULF waves on energetic particles in the radiation belts. Results from ULF wave-particle interaction models will be discussed in the context of pressure pulse or shock-excitation of magnetospheric ULF waves.