Guided Plasmaspheric Hiss Interactions with Superthermal Electrons

Under the proper conditions, guided plasmaspheric hiss is shown to be more efficient than Coulomb collisions at scattering electrons in the superthermal energy range of 50 to 500 eV. Broadband, whistler mode hiss becomes guided by plasma density gradients, intensifying the wave energy densities and focusing the wave normal angles. These waves are shown to interact through Cherenkov (Landau) resonance with electrons below 500 eV, and the presented equatorial plane timescales for pitch angle, energy, and mixed diffusion are shown to be faster than Coulomb collision timescales for typical values at the inner edge of the plasmapause and in detached plasma regions. In the latter case, energy diffusion timescales of less than 100 s for small pitch angle electrons between 250 and 500 eV indicate that these waves have the potential to dramatically change the distribution function

Simulation of magnetic cloud erosion during propagation

We examine a three‐dimensional (3‐D) numerical magnetohydrodynamic (MHD) simulation describing a very fast interplanetary coronal mass ejection (ICME) propagating from the solar corona to 1 AU. In conjunction with its high speed, the ICME evolves in ways that give it a unique appearance at 1 AU that does not resemble a typical ICME. First, as the ICME decelerates far from the Sun in the solar wind, filament material at the back of the flux rope pushes its way forward through the flux rope. Second, diverging nonradial flows in front of the filament transport poloidal flux of the rope to the sides of the ICME. Third, the magnetic flux rope reconnects with the interplanetary magnetic field (IMF). As a consequence of these processes, the flux rope partially unravels and appears to evolve to an entirely unbalanced configuration. At the same time, filament material at the base of the flux rope moves forward and comes in direct contact with the shocked plasma in the CME sheath. We find evidence that such remarkable behavior has actually occurred when we examine a very fast CME that erupted from the Sun on 2005 January 20. In situ observations of this event near 1 AU show very dense cold material impacting the Earth following immediately behind the CME sheath. Charge state analysis shows this dense plasma is filament material. Consistent with the simulation, we find the poloidal flux ( B z ) to be entirely unbalanced, giving the appearance that the flux rope has eroded. The dense solar filament material and unbalanced positive IMF B z produced a number of anomalous features in a moderate magnetic storm already underway, which are described in a companion paper by Kozyra et al. (2014). Key Points Filament material can move to the front of ICMEs Flux rope erosion can occur by azimuthal transport of poloidal fluxPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108271/1/jgra51093.pd

Reply to comment by R. M. Thorne and R. B. Horne on Khazanov et al. [2002] and Khazanov et al. [2006]

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95096/1/jgra18925.pd

Plasma properties of superstorms at geosynchronous orbit: How different are they?

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94769/1/grl23868.pd

Self-consistent Model of Magnetospheric Ring Current and Propagating Electromagnetic Ion Cyclotron Waves. 2. Wave Induced Ring Current Precipitation and Thermal Electron Heating

This paper continues presentation and discussion of the results from our new global self-consistent theoretical model of interacting ring current ions and propagating electromagnetic ion cyclotron waves [Khazanov et al., 2006]. To study the effects of electromagnetic ion cyclotron wave propagation and refraction on the wave induced ring current precipitation and heating of the thermal plasmaspheric electrons, we simulate the May 1998 storm. The main findings after a simulation can be summarized as follows. Firstly, the wave induced ring current precipitation exhibits quite a lot of fine structure, and is highly organized by location of the plasmapause gradient. The strongest fluxes of about 4 x 10(exp 6) (cm(raised dot) s(raised dot) sr(raised dot) (sup -1)) are observed during the maill and early recovery phases of the storm. The very interesting and probably more important finding is that in a number of cases the most intense precipitating fluxes are not connected to the most intense waves in simple manner. The characteristics of the wave power spectral density distribution over the wave normal angle are extremely crucial for the effectiveness of the ring current ion scattering. Secondly, comparison of the global proton precipitating patterns with the results from RAM [Kozyra et al., 1997a] reveals that although we observe a qualitative agreement between the localizations of the wave induced precipitations in the models, there is no quantitative agreement between the magnitudes of the fluxes. The quantitative differences are mainly due to a qualitative difference between the characteristics of the wave power spectral density distributions over the wave normal angle in RAM and in our model. Thirdly, the heat fluxes to plasmaspheric electrons caused by Landau resonate energy absorption from electromagnetic ion cyclotron waves are observed in the postnoon-premidnight MLT sector, and can reach the magnitude of 10(exp 11) eV/(cm(sup 2)(raised dot)s). The Coulomb energy degradation of the RC H(+) and O(+) ions maximizes at about 10(exp 11) (eV/(cm(sup 2) (raised dot) s), and typically leads to electron energy deposition rates of about 2(raised dot) 10(exp 10) (eV/(cm(sup 2)(raised dot)s) which are observed during two periods; 32-48 hours, and 76-86 hours after 1 May, 0000 UT. The theoretically derived spatial structure of the thermal electron heating caused by interaction of the ring current with the plasmasphere is strongly supported by concurrent and conjugate plasma measurements from the plasmasphere, ring current, and topside ionosphere [Gurgiolo et al., 2005]. Finally, the wave induced intense electron heating has a structure of the spot-like patches along the most enhanced density gradients in the plasmasphere boundary layer and can be a possible driver to the observed but still not explained small-scale structures of enhanced emissions in the stable auroral red arcs

Adiabatic energization in the ring current and its relation to other source and loss terms

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94822/1/jgra16175.pd

Dependence of plasmaspheric morphology on the electric field description during the recovery phase of the 17 April 2002 magnetic storm

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95341/1/jgra17301.pd

Global Simulation of Electromagnetic Ion Cyclotron Waves

It is very well known that the effects of electromagnetic ion cyclotron (EMIC) waves on ring current (RC) ion and radiation belt (RB) electron dynamics strongly depend on such particle/wave characteristics as the phase-space distribution function, frequency, wave-normal angle, wave energy, and the form of wave spectral energy density. The consequence is that accurate modeling of EMIC waves and RC particles requires robust inclusion of the interdependent dynamics of wave growth/damping, wave propagation, and particles. Such a self-consistent model is being progressively developed by Khazanov et al. This model is based on a system of coupled kinetic equations for the RC and EMIC wave power spectral density along with the ray tracing equations. We will discuss the recent progress in understanding EMIC waves formation mechanisms in the inner magnetosphere. This problem remains unsettled in spite of many years of experimental and theoretical studies. Modern satellite observations by CRRES, Polar and Cluster still do not reveal the whole picture experimentally since they do not stay long enough in the generation region to give a full account of all the spatio-temporal structure of EMIC waves. The complete self-consistent theory taking into account all factors significant for EMIC waves generation remains to be developed. Several mechanisms are discussed with respect to formation of EMIC waves, among them are nonlinear modification of the ionospheric reflection by precipitating energetic protons, modulation of ion-cyclotron instability by long-period (Pc3/4) pulsations, reflection of waves from layers of heavy-ion gyroresonances, and nonlinearities of wave generation process. We show that each of these mechanisms have their attractive features and explains certain part experimental data but any of them, if taken alone, meets some difficulties when compared to observations. We conclude that development of a refined nonlinear theory and further correlated analysis of modern satellite and ground-based data is needed to solve this very intriguing problem

Occurrence statistics of cold, streaming ions in the near‐Earth magnetotail: Survey of Polar‐TIDE observations

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95347/1/jgra17705.pd

A bounce‐averaged kinetic model of the ring current ion population

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/94668/1/grl7966.pd