Physics Department Seminar University of Alaska Fairbanks

J O U R N A L    C L U B


The role of ULF waves in the dynamics of the inner-magnetosphere and outer radiation belt

Dr. Kyle Murphy (NASA Goddard Space Flight Center)
A finalist candidate for the Physics faculty position



Ultra-Low Frequency (ULF) waves are a classification of geomagnetic pulsation observed by both in-situ spacecraft and ground-based instrumentation, such as magnetometers and radars. These waves are manifested in the Earths ionosphere and magnetosphere as perturbations of the local plasma and electric and magnetic fields with periods of ~0.1-1000s (frequencies ~1-10000 mHz). ULF waves are recognized as playing an important role in the overall dynamics of both the ionosphere and the magnetosphere, from the modulation of electron precipitation into the ionosphere, to the acceleration, transport, and loss of energetic particles within the inner-magnetosphere. In this talk I will investigate the role of ULF waves in the dynamics of energetic particles in the Earths inner-magnetosphere and in particular, the ring current and outer radiation belt. Using a database of ULF wave power, calculated from ground-based magnetometer observations of ULF waves from an entire solar cycle, I will demonstrate a clear relation between ULF waves and the strength of the Earth’s ring current as measured by the disturbance storm time index (Dst). Utilizing this same database of ULF wave power I will further demonstrate that ULF wave acceleration and transport of energetic electrons is a key process in radiation belt dynamics during geomagnetic storms (periods of extreme geomagnetic activity driven by Coronal Mass Ejections and Co-rotating Interaction Regions) as characterized by in-situ spacecraft. Overall this works demonstrates the importance of ULF waves in inner-magnetospheric dynamics and the utility of ground-based observations in the study of the Earth’s magnetosphere.


Note time: Friday, 17 February 2017

Globe Room, Elvey Building

3:30 PM