Magnetospheric Active Wave Measurements

Song, P.; Reinisch, B. W.; Huang, Xueqin; Green, J.L.

doi:10.1016/s0964-2749(05)80036-8

Cited by 12 publications

(21 citation statements)

References 32 publications

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“…The fluctuations of the O + , H + , and He + equatorial densities are due to the day‐night variations of the upward ionospheric fluxes. The time variations of the field‐aligned density distributions of O + , H + , and He + (data not shown) indicate that for each ion species, no shock is produced at any time of refilling and refilling is from the base ionospheres to the equator, consistent with the conclusions of Wilson et al [] and observations of Reinisch et al [, ], Huang et al [], Song et al [], and Ozhogin et al [, ].…”

Section: Simulation Results Of Plasmaspheric Refilling At L =supporting

confidence: 86%

A new dynamic fluid‐kinetic model for plasma transport within the plasmasphere

Wang

Song

2015

JGR Space Physics

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A new dynamic fluid‐kinetic model is developed for investigating the plasma transport along a closed magnetic flux tube in the plasmasphere by coupling the field line interhemispheric plasma (FLIP) model with a generalized semikinetic (GSK) model. The coupling is achieved via an overlapped transition region (800 km–1100 km altitude) in each of the hemispheres. The flux tube is allowed to move both radially away from, toward, and azimuthally around the Earth. In addition to H+, ion species O+ and He+ are for the first time treated as simulation particles in a numerical model of the plasmasphere. The simulation particles are subjected to the field‐aligned electric field, magnetic mirror force, gravity, centrifugal force, and interspecies and intraspecies Coulomb collisions. The plasmaspheric refilling processes as an application of the model are studied. The simulation results show that the behaviors of O+ ions are substantially different from those of H+ and He+ ions.

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Section: Simulation Results Of Plasmaspheric Refilling At L =supporting

confidence: 86%

A new dynamic fluid‐kinetic model for plasma transport within the plasmasphere

Wang

Song

2015

JGR Space Physics

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“…By scaling the trace (thin lines overlap on the traces) and using a density inversion technique described in detail by Huang et al [2004], we can derive an electron density profile (black line in Figure 1b). We then perform the least squares fit to the measured density profile using following expression [ Huang et al , 2004; Reinisch et al , 2004; Song et al , 2005] in order to determine the fitting parameters:

N (L, λ) = N_{italiceq} (L) \cdot (1 + γ \frac{λ}{λ_{INV}}) \cdot {cos}^{- β} [\frac{π}{2} \cdot \frac{α λ}{λ_{INV}}],

where L and λ INV are the L ‐shell in units of Earth radius R E , and the magnetic invariant latitude, respectively, of the geomagnetic field line on which the satellite made the measurements, and λ is the magnetic latitude on the field line. These values are calculated using the Tsyganenko 2001 (T01) [ Tsyganenko , 2002] magnetospheric magnetic field model.…”

Section: Data and Analysis Methodsmentioning

confidence: 99%

“…N eq is the equatorial density. It has been shown in previous studies that the functional form of well represents the field‐aligned density profiles in the filled plasmasphere on the dayside [ Huang et al, 2004; Reinisch et al , 2004; Song et al , 2005], as well as the field‐aligned density profiles along both the filled and depleted flux tubes around local midnight [ Tu et al , 2006]. Expression (1) has been developed empirically based on a large number of profiles and it provides extremely good fits for the majority of the cases (average relative error is less than 10%).…”

Section: Data and Analysis Methodsmentioning

confidence: 99%

“…Later on, whistler observations conducted both on the ground and on ISEE 1 spacecraft as well as in situ measurements from DE 1 and CRRES satellites were used to develop more sophisticated empirical plasmapause models [ Carpenter and Anderson , 1992; Moldwin et al , 2002; O'Brien and Moldwin , 2003]. In parallel to the modeling of the plasmapause location, empirical models of the equatorial density have also been developed with whistler observations, in situ probing, radio wave remote measurements, and extreme ultraviolet (EUV) imaging [e.g., Carpenter and Anderson , 1992; Sheeley et al , 2001; Denton et al , 2004; Reinisch et al , 2004; Song et al , 2005; Tu et al , 2006; Larsen et al , 2007]. Moreover, efforts have been made to statistically represent the plasmasphere/plasmatrough density distributions off the equator by using the measurements from the above mentioned spacecraft [ Gallagher et al , 1988, 1998, 2000; Goldstein et al , 2001; Denton et al , 2004; Huang et al , 2004; Reinisch et al , 2004; Tu et al , 2006].…”

Section: Introductionmentioning

confidence: 99%

“…In other words, the density is almost constant in a large latitudinal range around the equator for a given field line (or L ‐shell) [e.g., Gallagher et al , 2000]. However, the measurements from plasma wave instrument [ Gurnett et al , 1995] on the Polar spacecraft and, particularly, the radio plasma imager (RPI) [ Reinisch et al , 2000] on the IMAGE spacecraft have shown that density gradients along magnetic field lines are substantial and observable [ Goldstein et al , 2001; Denton et al , 2002, 2004; Huang et al , 2004; Reinisch et al , 2004; Song et al, 2005; Tu et al , 2006].…”

Section: Introductionmentioning

confidence: 99%

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Field‐aligned distribution of the plasmaspheric electron density: An empirical model derived from the IMAGE RPI measurements

Ozhogin¹,

Tu²,

Song³

et al. 2012

J. Geophys. Res.

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116

231

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[1] We present a newly developed empirical model of the plasma density in the plasmasphere. It is based on more than 700 density profiles along field lines derived from active sounding measurements made by the radio plasma imager on IMAGE between June 2000 and July 2005. The measurements cover all magnetic local times and vary from L = 1.6 to L = 4 spatially, with every case manually confirmed to be within the plasmasphere by studying the corresponding dynamic spectrogram. The resulting model depends not only on L-shell but also on magnetic latitude and can be applied to specify the electron densities in the plasmasphere between 2000 km altitude and the plasmapause (the plasmapause location itself is not included in this model). It consists of two parts: the equatorial density, which falls off exponentially as a function of L-shell; and the field-aligned dependence on magnetic latitude and L-shell (in the form of invariant magnetic latitude). The fluctuations of density appear to be greater than what could be explained by a possible dependence on magnetic local time or season, and the dependence on geomagnetic activity is weak and cannot be discerned. The solar cycle effect is not included because the database covers only a fraction of a solar cycle. The performance of the model is evaluated by comparison to four previously developed plasmaspheric models and is further tested against the in situ passive IMAGE RPI measurements of the upper hybrid resonance frequency. While the equatorial densities of different models are mostly within the statistical uncertainties (especially at distances greater than L = 3), the clear latitudinal dependence of the RPI model presents an improvement over previous models. The model shows that the field-aligned density distribution can be treated neither as constant nor as a simple diffusive equilibrium distribution profile. This electron density model combined with an assumed model of the ion composition can be used to estimate the time for an Alfven wave to propagate from one hemisphere to the other, to determine the plasma frequencies along a field line, and to calculate the raypaths for high frequency waves propagating in the plasmasphere.Citation: Ozhogin, P., J. Tu, P. Song, and B. W. Reinisch (2012), Field-aligned distribution of the plasmaspheric electron density: An empirical model derived from the IMAGE RPI measurements,

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Evaluating the diffusive equilibrium models: Comparison with the IMAGE RPI field‐aligned electron density measurements

Ozhogin

Song

et al. 2014

JGR Space Physics

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The diffusive equilibrium models that are widely used by the space physics community to describe the plasma densities in the plasmasphere are evaluated with field-aligned electron density measurements from the radio plasma imager (RPI) instrument onboard the IMAGE satellite. The original mathematical form of the diffusive equilibrium model was based on the hydrostatic equilibrium along the magnetic field line with the centrifugal force and the field-aligned electrostatic force as well as a large number of simplifying approximations. Six free parameters in the mathematical form have been conventionally determined from observations. We evaluate four sets of the parameters that have been reported in the literature. The evaluation is made according to the equatorial radial distance dependence, latitudinal dependence at a given radial distance, and the combined radial and latitudinal dependences. We find that the mathematical form given in the diffusive equilibrium model is intrinsically incompatible with the measurements unless another large number of free parameters are artificially introduced, which essentially changes the nature of a theoretical model to an empirical model.

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Magnetospheric Active Wave Measurements

Cited by 12 publications

References 32 publications

A new dynamic fluid‐kinetic model for plasma transport within the plasmasphere

A new dynamic fluid‐kinetic model for plasma transport within the plasmasphere

Field‐aligned distribution of the plasmaspheric electron density: An empirical model derived from the IMAGE RPI measurements

Evaluating the diffusive equilibrium models: Comparison with the IMAGE RPI field‐aligned electron density measurements

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