Motion of artificial ion clouds in the upper atmosphere

Haerendel, G.; Lüst, Reimar; Rieger, E.

doi:10.1016/0032-0633(67)90062-1

Cited by 182 publications

(55 citation statements)

References 9 publications

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“…As the barium vapor technique and theoretical principles, by which the electric field E is deduced from E = -V i x B by measuring the horizontal velocity V i of the ion cloud, have been discussed in detail previously [e.g., Haerendel et a., 1967;Wescott et al, 1969] they are not repeated here. The reader is also referred to Wescott et al, [1969] for descriptions and discussions of the rocket payload, the reaction chemistry in generating the vapor clouds, the cameras and film types used for photography, triangulation techniques, and errors in data reduction.…”

Section: Methodsmentioning

confidence: 99%

Electric-field measurements and the identification of currents causing magnetic disturbances in the polar cap

Heppner¹,

Stolarik²,

Wescott³

1971

J. Geophys. Res.

117

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Twelve Ba+ clouds were released at invariant latitudes 76° to 78° from three rockets launched from Cape Parry, Northwest Territories, Canada, for the study of polar‐cap electric fields and their relationship to polar‐cap magnetic‐field disturbances. All flights occurred under conditions characterized by Kp≈3. E was typically between 20 and 40 volts/km, directed roughly from dawn toward dusk, and was more uniform in space and time than E fields observed in the auroral belt. The measurements showed a large angular difference between the directions of E and ΔH, the horizontal polar‐cap magnetic disturbance. This meant that ΔH could not be caused solely by ionospheric Hall currents in the form of a sheet across the polar cap; also the sign of the difference was opposite to that expected from other elements of the conductivity tensor. Various factors lead to the conclusion that ΔH is caused almost entirely by a source other than overhead ionospheric currents. This conclusion has the consequence that continuity for Hall current auroral electrojets cannot be achieved by way of the polar‐cap and midlatitude ionospheres as assumed in the past. A mutual solution for both the ΔH problem and the continuity problem was found in terms of a new model for continutity of the Hall current auroral electrojets. Continuity by way of field‐aligned currents is primarily a consequence of (grad N)/N being greater than (grad E)/E. N = electron density at 100–130 km. The large‐scale properties of grad N/grad E appear to be compatible with the net distribution of field‐aligned currents required to explain both the polar cap ΔH and the simultaneous disturbance observed on the low‐latitude side of the auroral belt. The net field‐aligned currents are equivalent to two sheet currents flowing ‘out of’ and ‘into’ the auroral‐belt ionosphere, respectively, in the magnetic local time sectors 20–24h and 8–12h. Cause and effect between field‐aligned currents and precipitating particles is implied, in that the distribution of grad N at 100–130 km depends on the distribution of the precipitation.

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Section: Methodsmentioning

confidence: 99%

Electric-field measurements and the identification of currents causing magnetic disturbances in the polar cap

Heppner¹,

Stolarik²,

Wescott³

1971

J. Geophys. Res.

117

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“…Haerendel et al [1967], have derived an approximate expression for the transverse external electric field at infinity, E 1 , using a finite cylindrical ion cloud model. In…”

Section: Theoretical Considerationsmentioning

confidence: 99%

Electric fields in the vicinity of auroral forms from motions of barium vapor releases

Wescott¹,

Stolarik²,

Heppner³

1969

J. Geophys. Res.

170

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In August‐September 1967 eleven barium vapor clouds were released during evening twilight between invariant magnetic latitudes of 67.3° to 68.1° from Andøya, Norwav. Two flights (8 releases) occurred during moderate negative bays in H, whereas the third flight (3 releases) took place during a positive bay in H. Visual auroral displays were observed in the vicinity during all flights. In the negative bay situation, barium ion cloud motions were eastward and closely parallel to auroral arc alignments. Electric fields transverse to the magnetic field with intensities of 10–130 mv/m directed southward were observed. During the positive bay event the barium clouds spanned the breakup transition region, with the two equatorward clouds moving westward while the poleward cloud went east. Observed reversals in direction were closely correlated with magnetic variations. North‐directed electric fields of up to 50 mv/m were found in the positive bay sector. In all events the ion cloud motions revealed that E was perpendicular to the ionospheric current, hence we conclude that the auroral electrojets, both eastward and westward, are essentially Hall currents. The results illustrate that the magnitude of E driving ionospheric currents cannot be deduced solely from ground magnetic observations because of the variable ionospheric electrical conductivity. There is evidence that while E is large near an auroral arc, the field within is very low. Large gradients and/or irregularities in the E field are found to exist most of the time. These are revealed on three different time‐space scales: from differences in velocity for parallel moving clouds, from velocity changes along the path of a given cloud, and in the form of rayed structure within a cloud.

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“…During each of the twilight experiments the drift of Barium ion clouds was used to determine, rather precisely, the ionospheric electric field (HAERENDEL et al, 1967). On one other occasion, a double probe electric field instrument was flown (REES and MAYNARD, 1980) again to obtain a precise value for the high latitude electric field.…”

Section: Calculation Of the Ionospheric Current Densitymentioning

confidence: 99%

Mid-latitude winds and electric fields in the lower thermosphere and their relationship with the global Sq ionospheric current system.

Rees

1979

J. geomagn. geoelec

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The results of fifteen rocket measurements of neutral wind profiles, the ionospheric electric field and electron density at mid-latitudes are compared with the predictions of the dynamo theory of mid-latitude ionospheric currents (Sq) and the measurements of the ground-level magnetic perturbation. In daytime, the computed ionospheric currents agree well with both ground-level magnetic observations and Sq models, while the electric field structure is consistent with a dynamo source of such fields, although the field amplitude appears to be about 5000 of that predicted by models such as those of STENING (1973). At twilight there is a generally poorer agreement between the calculated currents and those indicated by magnetometers and by Sq models, probably due to difficulties of determining a precise magnetic baseline corresponding to zero electric current. At night, the wind system is occasionally strong enough to drive currents of 5 to 10 amps km-1 unless these are opposed by locally-induced, polarization electric fields of the order of 5 to 10mVm-1. Such fields may be readily induced, at mid-latitudes, by the high-speed, night-time wind systems set up by high latitude energetic processes during geomagnetic substorms, without requiring a direct penetration of magnetospheric, convective fields to low magnetic latitudes.

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Motion of artificial ion clouds in the upper atmosphere

Cited by 182 publications

References 9 publications

Electric-field measurements and the identification of currents causing magnetic disturbances in the polar cap

Electric-field measurements and the identification of currents causing magnetic disturbances in the polar cap

Electric fields in the vicinity of auroral forms from motions of barium vapor releases

Mid-latitude winds and electric fields in the lower thermosphere and their relationship with the global Sq ionospheric current system.

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