title: Applying the cold plasma dispersion relation to whistler mode chorus waves: EMFISIS wave measurements from the Van Allen Probes.
abstract: Most theoretical wave models require the power in the wave magnetic field in order to determine the effect of chorus waves on radiation belt electrons. However, researchers typically use the cold plasma dispersion relation to approximate the magnetic wave power when only electric field data are available. In this study, the validity of using the cold plasma dispersion relation in this context is tested using Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) observations of both the electric and magnetic spectral intensities in the chorus wave band (0.1-0.9fce). Results from this study indicate that the calculated wave intensity is least accurate during periods of enhanced wave activity. For observed wave intensities >10-3nT2, using the cold plasma dispersion relation results in an underestimate of the wave intensity by a factor of 2 or greater 56% of the time over the full chorus wave band, 60% of the time for lower band chorus, and 59% of the time for upper band chorus. Hence, during active periods, empirical chorus wave models that are reliant on the cold plasma dispersion relation will underestimate chorus wave intensities to a significant degree, thus causing questionable calculation of wave-particle resonance effects on MeV electrons.
authors.affiliation: Physics Department, Lancaster University Lancaster, UK.
authors.forename: D P
authors.initials: DP
authors.lastname: Hartley
authors.affiliation: Los Alamos National Laboratory Los Alamos, New Mexico, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Department of Physics and Astronomy, University of Iowa Iowa City, Iowa, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Kletzing
authors.affiliation: Space Science Institute Boulder, Colorado, USA.
authors.forename: M H
authors.initials: MH
authors.lastname: Denton
authors.affiliation: Department of Physics and Astronomy, University of Iowa Iowa City, Iowa, USA.
authors.forename: W S
authors.initials: WS
authors.lastname: Kurth
keywords: EMFISIS; Van Allen Probes; chorus waves; energetic electrons; radiation belts; wave-particle interactions