Model of the energization of outer‐zone electrons by whistler‐mode chorus during the October 9, 1990 geomagnetic storm

Summers, Danny; Ma, Cong; Meredith, Nigel P.; Horne, Richard B.; Thorne, R. M.; Heynderickx, D.; Anderson, R. R.

doi:10.1029/2002gl016039

Cited by 187 publications

(204 citation statements)

References 19 publications

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“…The sporadic injections of energetic, anisotropic~10-100-keV electrons will generate chorus waves more or less continuously. Chorus generation is reported during geomagnetic storms (Horne and Thorne 1998;Summers et al 1998Summers et al , 2002Meredith et al 2002;Horne et al 2003Horne et al , 2005aHorne et al , 2005bHorne et al , 2007). However, the particle injections during storms are deeper into the magnetosphere (stronger convection electric fields) and last for only hours of duration.…”

Section: Discussionmentioning

confidence: 99%

Relativistic electron acceleration during HILDCAA events: are precursor CIR magnetic storms important?

et al. 2015

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We present a comparative study of high-intensity long-duration continuous AE activity (HILDCAA) events, both isolated and those occurring in the "recovery phase" of geomagnetic storms induced by corotating interaction regions (CIRs). The aim of this study is to determine the difference, if any, in relativistic electron acceleration and magnetospheric energy deposition. All HILDCAA events in solar cycle 23 (from 1995 through 2008) are used in this study. Isolated HILDCAA events are characterized by enhanced fluxes of relativistic electrons compared to the pre-event flux levels. CIR magnetic storms followed by HILDCAA events show almost the same relativistic electron signatures. Cluster 1 spacecraft showed the presence of intense whistler-mode chorus waves in the outer magnetosphere during all HILDCAA intervals (when Cluster data were available). The storm-related HILDCAA events are characterized by slightly lower solar wind input energy and larger magnetospheric/ionospheric dissipation energy compared with the isolated events. A quantitative assessment shows that the mean ring current dissipation is~34 % higher for the storm-related events relative to the isolated events, whereas Joule heating and auroral precipitation display no (statistically) distinguishable differences. On the average, the isolated events are found to be comparatively weaker and shorter than the storm-related events, although the geomagnetic characteristics of both classes of events bear no statistically significant difference. It is concluded that the CIR storms preceding the HILDCAAs have little to do with the acceleration of relativistic electrons. Our hypothesis is that~10-100-keV electrons are sporadically injected into the magnetosphere during HILDCAA events, the anisotropic electrons continuously generate electromagnetic chorus plasma waves, and the chorus then continuously accelerates the high-energy portion of this electron spectrum to MeV energies.

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Section: Discussionmentioning

confidence: 99%

Relativistic electron acceleration during HILDCAA events: are precursor CIR magnetic storms important?

et al. 2015

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“…We use our optimized loss time scale to model the 9 October 1990 storm (Brautigam and Albert, 2000;Meredith et al, 2002;Summers et al, 2002), (Fig. 3, top panel).…”

Section: Simulations Of October 1990 Stormmentioning

confidence: 99%

Radial diffusion modeling with empirical lifetimes: comparison with CRRES observations

et al. 2005

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Abstract.A time dependent radial diffusion model is used to quantify the competing effects of inward radial diffusion and losses on the distribution of the outer zone relativistic electrons. The rate of radial diffusion is parameterized by K p with the loss time as an adjustable parameter. Comparison with HEEF data taken over 500 Combined Release and Radiation Effects Satellite (CRRES) orbits indicates that 1-MeV electron lifetimes near the peak of the outer zone are less than a day during the storm main phase and few days under less disturbed conditions. These values are comparable to independent estimates of the storm time loss rate due to scattering by EMIC waves and chorus emission, and also provide an acceptable representation of electron decay rates following the storm time injection. Although our radial diffusion model, with data derived lifetimes, is able to simulate many features of the variability of outer zone fluxes and predicts fluxes within one order of magnitude accuracy for most of the storms and L values, it fails to reproduce the magnitude of flux changes and the gradual build up of fluxes observed during the recovery phase of many storms. To address these differences future modeling should include an additional local acceleration source and also attempt to simulate the pronounced loss of electrons during the main phase of certain storms.

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“…Cyclotron resonant whistlermode-wave-electron interactions are an important controlling factor in radiation belt electron dynamics. Relativistic (∼ MeV) electrons can be generated in the outer radiation belt due to cyclotron resonance with chorus (Summers et al, 1998(Summers et al, , 2002(Summers et al, , 2007aRoth et al, 1999;Meredith et al, 2003;Summers and Omura, 2007;Xiao et al, 2010;Su et al, 2014). Chorus waves can pitch-angle scatter outer zone electrons into the loss cone and induce particle loss to the atmosphere (Lorentzen et al, 2001;O'Brien et al, 2004;Thorne et al, 2005;Summers et al, 2007a, b;Ni et al, 2008;Hikishima et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Effects of cold electron number density variation on whistler-mode wave growth

2014

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Abstract. We examine how the growth of magnetospheric whistler-mode waves depends on the cold (background) electron number density N 0 . The analysis is carried out by varying the cold-plasma parameter a = (electron gyrofrequency) 2 /(electron plasma frequency) 2 which is proportional to 1/N 0 . For given values of the thermal anisotropy A T and the ratio N h /N 0 , where N h is the hot (energetic) electron number density, we find that, as N 0 decreases, the maximum values of the linear and nonlinear growth rates decrease and the threshold wave amplitude for nonlinear growth increases. Generally, as N 0 decreases, the region of (N h /N 0 , A T )-parameter space in which nonlinear wave growth can occur becomes more limited; that is, as N 0 decreases, the parameter region permitting nonlinear wave growth shifts to the top right of (N h /N 0 , A T ) space characterized by larger N h /N 0 values and larger A T values. The results have implications for choosing input parameters for full-scale particle simulations and also in the analysis of whistler-mode chorus data.

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Model of the energization of outer‐zone electrons by whistler‐mode chorus during the October 9, 1990 geomagnetic storm

Cited by 187 publications

References 19 publications

Relativistic electron acceleration during HILDCAA events: are precursor CIR magnetic storms important?

Relativistic electron acceleration during HILDCAA events: are precursor CIR magnetic storms important?

Radial diffusion modeling with empirical lifetimes: comparison with CRRES observations

Effects of cold electron number density variation on whistler-mode wave growth

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