Studies of planetary atmospheres: 1. The distribution of electrons and ions in the Earth's exosphere

Angerami, J. J.; Thomas, Jean O.

doi:10.1029/jz069i021p04537

Cited by 338 publications

(154 citation statements)

References 25 publications

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“…At higher levels, the diffusion problem becomes complicated due to the presence of more than one species. The diffusive equilibrium theory was first described by Dungey [1955] for two ion species and for multiconstituent plasma by Angerami and Thomas [1964]. Also, the dynamical nature of the topside ionosphere and plasmasphere is quite complex owing to the relatively large time constants associated with the plasma flow characteristics and the frequent occurrences of plasma disturbances caused by various sources.…”

Section: Discussionmentioning

confidence: 99%

A new method for reconstruction of the vertical electron density distribution in the upper ionosphere and plasmasphere

et al. 2003

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[1] Ground-based ionosphere sounding measurements alone are incapable of reliably modeling the topside electron density distribution above the F layer peak density height. Such information can be derived from Global Positioning System (GPS)-based total electron content (TEC) measurements. A novel technique is presented for retrieving the electron density height profile from three types of measurements: ionosonde ( f o F 2 , f o E, M 3000 F 2 , h m f 2 ), TEC (GPS-based), and O + -H + ion transition level. The method employs new formulae based on Chapman, sech-squared, and exponential ionosphere profilers to construct a system of equations, the solution of which system provides the unknown ion scale heights, sufficient to construct a unique electron density profile at the site of measurements. All formulae are based on the assumption of diffusive equilibrium with constant scale height for each ion species. The presented technique is most suitable for middle-and high-geomagnetic latitudes and possible applications include: development, evaluation, and improvement of theoretical and empirical ionospheric models, development of similar reconstruction methods utilizing low-earth-orbiting satellite measurements of TEC, operational reconstruction of the electron density on a real-time basis, etc.

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Section: Discussionmentioning

confidence: 99%

A new method for reconstruction of the vertical electron density distribution in the upper ionosphere and plasmasphere

et al. 2003

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“…This approach yields a first approximation, which is qualitatively useful, although ion composition is likely to vary during this second time interval. Actually, the diffusive equilibrium model (Angerami and Thomas, 1964; see also Sonwalkar et al, 2011b) indicates that the effective ion mass is increasing with decreasing distance along the line of force (from a base level of 500 km) which is the case here, from time interval I to time interval II, and in a more significant manner, during interval II (altitudes in the range 1600-1200 km). If this is indeed the case, then the plasma frequency profile indicates a lower threshold of local electron density along the orbit.…”

Section: Specific Situation Encountered On Clustermentioning

confidence: 99%

Lower hybrid resonances stimulated by the four CLUSTER relaxation sounders deep inside the plasmasphere: observations and inferred plasma characteristics

Kougblénou¹,

Lointier²,

Décréau³

et al. 2011

Ann. Geophys.

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Abstract. The frequency range of the WHISPER relaxation sounder instrument on board CLUSTER, 4-80 kHz, has been chosen so as to encompass the electron gyro-frequency, F ce , and the electron plasma frequency, F p , in most regions to be explored. Measurement of those frequencies, which are triggered as resonances by the sounder, provides a direct estimation of in situ fundamental plasma characteristics: electron density and magnetic field intensity. In the late mission phase, CLUSTER penetrated regions deep inside the plasmasphere where F ce and F p are much higher than the upper frequency of the sounder's range. However, they are of the right order of magnitude as to place the lower hybrid frequency, F lh , in the 4-15 kHz band. This characteristic frequency, placed at a resonance of the medium, is triggered by the sounder's transmitter and shows up as an isolated peak in the received spectrum, not present in spectra of naturally occuring VLF waves. This paper illustrates, from analysis of case events, how measured F lh values give access to a plasma diagnostic novel of its kind. CLUSTER, travelling along its orbit, encounters favourable conditions where F ce is increasing and F p decreasing, such that F ce /F p increases from values below unity to values above unity. Measured F lh values thus give access, in turn, to the effective mass, M eff , indicative of plasma ion composition, and to the core plasmasphere electron density value, a parameter difficult to measure. The analysed case events indicate that the estimated quantities (M eff in the 1.0-1.4 range, N e in the 5 × 10 2 -10 4 cm −3 range) are varying with external factors (altitude, L value, geomagnetic activity) in a plausible way. Although covering only a restricted region (mid-latitude, low altitude inner plasmasphere), these measurements are available, sinceCorrespondence to: S. Kougblénou (sena.kougblenou@cnrs-orleans.fr) late 2009, for all CLUSTER perigee passes not affected by eclipses (on average, roughly a third of a total of ∼200 passes per year) and offer multipoint observations previously unavailable in this region.

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“…To estimate the contribution of the plasmaspheric region to the observed TEC value, we employ a simple diffusive equilibrium model proposed by Angerami and Thomas [22]. According to this model we assume the electron density distribution in the plasmasphere n(h) is decreasing exponentially from the top of the ionospheric region (h 0 = 700 km) with the scale length H s up to the satellite orbits (h sat = 20200 km).…”

Section: Some Issues Specific To the Ct Of The Ionospheric Electron Dmentioning

confidence: 99%

Ionospheric Tomography by Neural Network Collocation Method

Takeda

2007

Plasma and Fusion Research

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We describe a neural network collocation method (NNCM) for tomographic image reconstruction with small amount of projection data, which has been successfully applied to the three-dimensional ionospheric tomography based on the dataset of signal delays from the GPS satellites. In NNCM the neural network is trained by minimizing an object function composed of squared residuals of the governing equations evaluated at the collocation points and some constraining conditions imposed usually by observation data. This method is applied not only to the computerized tomography but also to the analyses of various inverse problems such as the data assimilation, the parameter estimation, the time series prediction, and so on.

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Studies of planetary atmospheres: 1. The distribution of electrons and ions in the Earth's exosphere

Cited by 338 publications

References 25 publications

A new method for reconstruction of the vertical electron density distribution in the upper ionosphere and plasmasphere

A new method for reconstruction of the vertical electron density distribution in the upper ionosphere and plasmasphere

Lower hybrid resonances stimulated by the four CLUSTER relaxation sounders deep inside the plasmasphere: observations and inferred plasma characteristics

Ionospheric Tomography by Neural Network Collocation Method

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