Increase in relativistic electron flux in the inner magnetosphere: ULF wave mode structure

Hudson, M. K.; Elkington, S. R.; Lyon, J. G.; Goodrich, C. C.

doi:10.1016/s0273-1177(99)00518-9

Cited by 119 publications

(111 citation statements)

References 16 publications

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“…This maximizes at the interface and then decays even more slowly than the ap index. These waves are highly correlated with large increases in the flux of relativistic electrons at synchronous orbit [Green and Kivelson, 2001;O'Brien et al, 2001] and hence are though to play a role in the acceleration of these electrons [Hudson et al,;Liu et al, 1999].…”

Section: Cumulative Probablity Distributions For Indices Relative To mentioning

confidence: 99%

Probabilistic Forecasting of the Dst Index

McPherron

Siscoe

Crooker

et al. 2013

The Inner Magnetosphere: Physics and Modeling

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The Dst index can be predicted by an autoregressive moving average filter that transforms the solar wind electric field and dynamic pressure into changes in the index. Integration of these changes gives Dst. The maximum lead time possible is less than 60 minutes. Longer lead times are probably unobtainable due to the stochastic nature of IMF Bz. In this paper we use photospheric observations of the solar magnetic field to predict Dst. Our technique uses the Wang-Sheeley-Arge (W-S-A) model to forecast the time variations of solar wind speed, IMF polarity, and IMF strength at Earth four days in advance. Since the waveform of Bz is incalculable from solar observations we make use of air mass climatology. In this technique the cumulative probability distribution is determined as a function of time relative to a stream interface. During the declining phase of the solar cycle persistent coronal holes create high speed streams. The interface between these streams and slower speed solar wind ahead provides a reference time that can be used to organize the cumulative probability distributions determined from historic data (climatology). We then use the predicted arrival of an interface and the associated cumulative distributions to predict the probability that |Dst| will fall within a range of values. This technique works best for small to moderate storms occurring during the declining phase of the solar cycle. CMEs are not predictable by this model hence we do not expect this approach to work as well at solar maximum.

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Section: Cumulative Probablity Distributions For Indices Relative To mentioning

confidence: 99%

Probabilistic Forecasting of the Dst Index

McPherron

Siscoe

Crooker

et al. 2013

The Inner Magnetosphere: Physics and Modeling

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“…Mathie and Mann (2000) and O'Brien et al (2001) established a correlation between relativistic electron events at L = 6.6 and prolonged ULF wave activity during the storm recovery. Liu et al (1999) proposed an acceleration mechanism involving magnetic pumping by ULF waves, while Hudson et al (2000) and Elkington et al (1999) proposed a mechanism involving drift resonant acceleration by ULF waves associated with inward radial transport. Drift resonant acceleration with ULF waves also conserves the first two adiabatic invariants but breaks the third and is one of the drivers for radial diffusion.…”

Section: Introductionmentioning

confidence: 99%

Evidence for acceleration of outer zone electrons to relativistic energies by whistler mode chorus

et al. 2002

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Abstract. We use plasma wave and electron data from the Combined Release and Radiation Effects Satellite (CRRES) to investigate the viability of a local stochastic electron acceleration mechanism to relativistic energies driven by gyroresonant interactions with whistler mode chorus. In particular, we examine the temporal evolution of the spectral response of the electrons and the waves during the 9 October 1990 geomagnetic storm. The observed hardening of the electron energy spectra over about 3 days in the recovery phase is coincident with prolonged substorm activity, as monitored by the A E index and enhanced levels of whistler mode chorus waves. The observed spectral hardening is observed to take place over a range of energies appropriate to the resonant energies associated with Doppler-shifted cyclotron resonance, as supported by the construction of realistic resonance curves and resonant diffusion surfaces. Furthermore, we show that the observed spectral hardening is not consistent with energy-independent radial diffusion models. These results provide strong circumstantial evidence for a local stochastic acceleration mechanism, involving the energisation of a seed population of electrons with energies of the order of a few hundred keV to relativistic energies, driven by wave-particle interactions involving whistler mode chorus. The results suggest that this mechanism contributes to the reformation of the relativistic outer zone population during geomagnetic storms, and is most effective when the recovery phase is characterised by prolonged substorm activity. An additional significant result of this paper is that we demonstrate that the lower energy part of the storm-time electron distribution is in steady-state balance, in accordance with the Kennel and Petschek (1966) theory of limited stably-trapped particle fluxes.

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“…Increase in the magnitude of D 8t causes a measurable dropout in geosynchronous elec tron flux in all four events, due to main phase buildup of the ring current and third invariant conservation (Kim and Chan, 1998). Plots of relative energy flux in four energy channels measured by GPS spacecraft at their equatorial radial crossing point have reproduced the de crease in flux associated with D s t ; for simulated geosynchronous orbit, magnetosheath en counters that coincide with those seen by LANL space craft are also reproduced by the MHD-test particle sim ulations (Hudson et al, 2000), as is the diurnal variation in geosynchronous flux due to the compressed dipole, enhanced during storm periods .…”

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confidence: 59%

“…Parameters measured at the WIND spacecraft have been used to drive a 3D global MHD simulation (Goodrich et al, 1998) for the four storms. The field output from these simulations has been analyzed for MHD mode structure (Hudson et al, 2000), and used as input to a guiding center test particle code which advances electron flux in the equatorial plane . This paper compares the relative geoeffectiveness of the four storms, as measured by the rate of relativistic electron radial transport and first invariant conserving acceleration.…”

Section: Introductionmentioning

confidence: 99%

Radiation Belt Electron Acceleration by ULF Wave Drift Resonance: Simulation of 1997 and 1998 Storms

Hudson

Elkington

Lyon

et al. 2013

Geophysical Monograph Series

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Pc 5 ULF waves are seen concurrently with the rise in radiation belt fluxes associated with CME-magnetic cloud events. Four such geomagnetic storm periods in 1997 and 1998, 10-11 January and 14-15 May, 1997; 1-4 May and 26-28 August, 1998, have been simulated with a 3D global MHD code driven by Ll-measured solar wind parameters. The field output has been used to advance electron guiding center trajectories in the equatorial plane. The time series has also been analyzed for ULF wave mode structure. Toroidal field line resonances with low azimuthal mode number and frequencies com mensurate with the electron drift period are identified in the radial electric field component, along with enhanced power in the poloidal (azimuthal) elec tric field component. The simulated time scale for inward radial transport of electrons in the several hundred keV to MeV energy range, from geosyn chronous orbit to L=3-4, varies with the level of ULF wave power and overall energy input to the magnetosphere. Of the four events studied, the May 1998 storm period was most geoeffective and the January 1997 least so, in terms of simulated radial transport and energization of electrons. This transport rate is consistent with the level of ULF waves excited in the simulations, and the proposed drift resonant acceleration mechanism.

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Increase in relativistic electron flux in the inner magnetosphere: ULF wave mode structure

Cited by 119 publications

References 16 publications

Probabilistic Forecasting of the Dst Index

Probabilistic Forecasting of the Dst Index

Evidence for acceleration of outer zone electrons to relativistic energies by whistler mode chorus

Radiation Belt Electron Acceleration by ULF Wave Drift Resonance: Simulation of 1997 and 1998 Storms

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