Direct detection by a Whistler method of the magnetospheric electric field associated with a polar substorm

Carpenter, D. L.; Stone, Keppler

doi:10.1016/0032-0633(67)90203-6

Cited by 124 publications

(30 citation statements)

References 2 publications

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“…The two may be related by assuming that the field lines are equipotentials (Mozer, 1973): a factor of L'213 is introduced in mapping from the ionosphere to the equatorial plane in a dipole field. Electric fields by means of groundreceived whistlers during substorms have widely been observed (e.g., Carpenter and Stone, 1967;Carpenter et al, 1972;Park, 1976Park, , 1978. Typical average values of equatorial east-ward electric field during substorms are 0.2-0.3 mV/m, depending on the level of magnetic activity.…”

Section: Resultsmentioning

confidence: 99%

“…Typical average values of equatorial east-ward electric field during substorms are 0.2-0.3 mV/m, depending on the level of magnetic activity. On the other hand, the few quiet time observations of electric fields (Carpenter and Seely, 1976;Carpenter, t978;Rash etal.,1986) yield values of eastwest electric field JEwl of 0.1 mV/m. Irregularities in the electric field of this order are thought to be associated with the formation of whistler ducts (Park and Helliwell, 197 1;Lester and Smith, 1980).…”

Section: Resultsmentioning

confidence: 99%

“…If fn increases with time, then electric field is directed from east to west and in the reversal case it is directed from west to east. This measurement is almost independent of the model of electron distribution assumed (Carpenter et al, 1972;Sagredo et al, 1973). With the nose frequency expressed in Hz one can directly estimate the convection electric field from the slope off 213 using Eq.…”

Section: Methods Of Analysismentioning

confidence: 99%

“…Plasma flow between ionosphere and plasmasphere in terms of the downward flux of ionization is known to contribute to the maintenance of the nocturnal ionosphere (Bailey et al, 1987;Lalmani et al, 1992). In order to interpret the whistler duct drift data in terms of bulk motion of the magnetospheric plasma in which the ducts are embedded, recourse is taken to two assumptions (Carpenter and Seely, 1976) namely; that the ducts are of limited cross section (Angerani, 1970) and that they move with the surrounding plasma (Carpenter et al, 1972). In deducing the electric field from the drifting of ducts, the motion is assumed to be E x B origin.…”

Section: Introductionmentioning

confidence: 99%

“…The plasmapause or the ring current acts to shield the plasmasphere from the external magnetospheric convection field (Block, 1966;Swift, 1971;Vasyliunas 1972). It is believed (Woodman, 1970;Mozer, 1971aMozer, , b, 1973Carpenter et al, 1972;Blanc, 1983;Mazaudier et al, 1984) that the magnetospheric convection electric field does not penetrate to low latitudes at least for field changes on time scale less than 10 h, such as those associated with magnetospheric substorms (Gonzales et al, 1983). It is also not clear as to what extent such penetration of the magnetospheric electric field occurs under steady and quiet periods (Mozer, 1973;Richmond et al, 1976;Blanc et al, 1977).…”

Section: Introductionmentioning

confidence: 99%

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An Estimate of Quiet Time Plasmaspheric Electric Fields from Whistler Observations at Low Latitude.

Lalmani¹,

Ahmad²,

Singh

1996

J. geomagn. geoelec

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Particular emphasis is laid on the application of whistlers recorded at low latitude ground station, Nainital during magnetically quiet times to estimate the eastward/westward electric field in the plasmasphere. The east-west components of electric field during quiet magnetic (average Kp = 1) are obtained for the first time from low latitude station on the basis of the available whistler data on Tarcsai (1975). Our measurements demonstrate an average estimated electric field of-0.06 mVm 1 in the premidnight local time sector and an average westward electric field of -0.05 mVm I in the post-midnight local time sector. These values are in good agreement with similar results reported by earlier workers. Near midnight there is a sharp transition from eastward field to westward electric field. The electric fields during quiet days at low latitudes are thought to be generated by the dynamo mechanism.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methods Of Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

An Estimate of Quiet Time Plasmaspheric Electric Fields from Whistler Observations at Low Latitude.

Lalmani¹,

Ahmad²,

Singh

1996

J. geomagn. geoelec

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Empirical Modeling of the Plasmasphere Dynamics Using Neural Networks

2017

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We present the PINE (Plasma density in the Inner magnetosphere Neural network‐based Empirical) model ‐ a new empirical model for reconstructing the global dynamics of the cold plasma density distribution based only on solar wind data and geomagnetic indices. Utilizing the density database obtained using the NURD (Neural‐network‐based Upper hybrid Resonance Determination) algorithm for the period of 1 October 2012 to 1 July 2016, in conjunction with solar wind data and geomagnetic indices, we develop a neural network model that is capable of globally reconstructing the dynamics of the cold plasma density distribution for 2≤L≤6 and all local times. We validate and test the model by measuring its performance on independent data sets withheld from the training set and by comparing the model‐predicted global evolution with global images of He+ distribution in the Earth's plasmasphere from the IMAGE Extreme UltraViolet (EUV) instrument. We identify the parameters that best quantify the plasmasphere dynamics by training and comparing multiple neural networks with different combinations of input parameters (geomagnetic indices, solar wind data, and different durations of their time history). The optimal model is based on the 96 h time history of Kp, AE, SYM‐H, and F10.7 indices. The model successfully reproduces erosion of the plasmasphere on the nightside and plume formation and evolution. We demonstrate results of both local and global plasma density reconstruction. This study illustrates how global dynamics can be reconstructed from local in situ observations by using machine learning techniques.

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Recent Research on the Magnetospheric Plasmapause

Carpenter¹

1968

Radio Science

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The plasmapause is a three‐dimensional field aligned boundary that divides the closed field‐line portion of the earth's magnetosphere into two physically distinct regions. The boundary is asymmetric, usually exhibiting a minimum geocentric range near dawn and a maximum near dusk under conditions of moderate but steady geomagnetic agitation (Kp = 2 − 4). The mean equatorial radius of the plasmapause is typically about 4RE, but it may vary from about 5.5RE during periods of extreme quiet to the range 2 − 3RE during great storms. The approximately corotating thermal plasma within the boundary exhibits two types of radial drift motions. These may be visualized as: (a) slow “breathing“ motions that follow the radial variations in a fixed, asymmetric boundary; (b) more rapid, transient (1 − 2 hr) motions that occur when the boundary position varies, as is the case during a polar substorm. The plasmapause involves an abrupt change in electron density, in tube electron content above 1000 km, and possibly in plasma bulk velocity and mean thermal energy. To the ionosphere, the protonosphere inside the plasmapause appears as a large reservoir of thermal protons, while the region outside appears virtually empty. At the plasmapause, equatorial values of electron density change by a factor of 10 to 100 within less than 0.15 earth radii. Satellite VLF experiments suggest that the change may be far more abrupt than this, possibly on a scale of a few kilometers. Studies of the distribution of electron density along the field line in the plasmapause have shown that earlier empirical models of the type N ∝ R−3 are not, in fact, compatible with recent satellite data on topside electron concentrations. Instead, the theoretically palatable diffusive equilibrium model has been found to be an appropriate description for most of the plasmasphere, while a more rapidly varying model appears necessary to describe the tenuous outer region. Details of the latter distribution may vary in important ways as a function of local time. Many wave propagation phenomena of conjugate interest are strongly affected by the presence of the plasmapause. For example, satellites moving poleward through the boundary observe a cutoff in whistlers propagating from the conjugate hemisphere; a decrease in the intensity of fixed‐frequency VLF signals propagating upward, and dramatic changes in VLF noise such as the lower hybrid resonance (LHR) noise. In ground recordings made at Eights (L ∼ 4) and Byrd (L ∼ 7) in the austral winter, four distinct magnetospheric regions of propagation may be identified: (I) the outer part of the plasmasphere; (II) the outer “surface” of the plasmapause; (Ill) a belt‐like region extending 1−2 RE outward from the near vicinity of the plasmapause; (IV) a region beginning ∼ 1.5 RE beyond the plasmapause and extending several earth radii outward. Each region exhibits special properties with respect to the occurrence and spectral behavior of VLF noise, and, in particular, noise triggered by whistler components. The occurrence of one‐hop ...

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Direct detection by a Whistler method of the magnetospheric electric field associated with a polar substorm

Cited by 124 publications

References 2 publications

An Estimate of Quiet Time Plasmaspheric Electric Fields from Whistler Observations at Low Latitude.

An Estimate of Quiet Time Plasmaspheric Electric Fields from Whistler Observations at Low Latitude.

Empirical Modeling of the Plasmasphere Dynamics Using Neural Networks

Recent Research on the Magnetospheric Plasmapause

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