University of Minnesota
School of Physics & Astronomy

Space Physics Seminar

Tuesday, November 27th 2018
12:15 pm:
Speaker: Evan Tyler, University of Minnesota
Subject: A Statistical Study of High Amplitude Whistler-mode Waves Using 5 Years of Van Allen Probes Data
Note change of time and location, this week only. This is the public portion of Mr. Tyler's Thesis Defense.

Abstract: We present the first statistical analysis with continuous data coverage and non-averaged amplitudes of the prevalence and distribution of high-amplitude (> 5 mV/m or > 50 pT) whistler- mode waves in the outer radiation belt using 5 years of Van Allen Probes data. Large-amplitude electric fields are most common above L=3.5 and between MLT of 0-7 where they are present 1-4% of the time. Large-amplitude magnetic fields are most common above L=4.5 and between MLT of 0-14 where they are present 1-6% of the time. During high geomagnetic activity, high-amplitude whistler-mode wave occurrence rises above 30% in some regions. During these active times the plasmasphere erodes to lower L and a significant population of large-amplitude, quasi-electrostatic whistler waves are observed at the plasmapause boundary at low L (3.5-4) in the pre-dawn sector. Because our knowledge of the distribution of magnetospheric chorus and other whistler mode waves in the magnetosphere has been primarily built on studies using time averaged data, the space physics community has previously been unable to determine the generation, prevalence, or impact of large-amplitude whistler-mode waves in the magnetosphere. Since these waves were first observed, their behavior and importance has been poorly constrained. These new results have important implications for modeling radiation belt particle interactions with chorus, as large-amplitude waves interact non-linearly with electrons. This also may provide clues regarding the mechanisms which result in growth to large amplitudes.

The weekly calendar is also available via subscription to the physics-announce mailing list, and by RSS feed.