Climatology of high-β plasma measurements in Earth's inner magnetosphere

Ross Cohen, Andrew Gerrard, Louis J. Lanzerotti, Angel Soto Chavez, Hyomin Kim, Jerry W. Manweiler

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Since their launch in August 2012, the Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instruments on the NASA Van Allen Probes spacecraft have been making continuous high-resolution measurements of Earth's ring current plasma environment. After a full traversal through all magnetic local times, a climatology (i.e., a survey of observations) of high-beta (β) plasma events (defined here as β > 1) as measured by the RBSPICE instrument in the ∼45 keV to ∼600 keV proton energy range in the inner magnetosphere (L < 5.8) has been constructed. In this paper we report this climatology of such high-β plasma occurrences, durations, and their general characteristics. Specifically, we show that most high-β events in the RBSPICE energy range are associated with postdusk/premidnight sector particle injections or plasma patches and can last from minutes to hours. While most of these events have a β less than 2, there are a number of observations reaching β greater than 4. Other observations of particular note are high-β events during relatively minor geomagnetic storms and examples of very long duration high-β plasmas. We show that high-β plasmas are a relatively common occurrence in the inner magnetosphere during both quiet and active times. As such, the waves generated by these plasmas may have an underappreciated role in the inner magnetosphere, and thus the study of these plasmas and their instabilities may be more important than has been currently addressed.

Original languageEnglish (US)
Pages (from-to)711-726
Number of pages16
JournalJournal of Geophysical Research: Space Physics
Issue number1
StatePublished - Jan 1 2017

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Space and Planetary Science


  • Van Allen Probes
  • climatology
  • high-beta plasma
  • inner magnetosphere


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