Conjugate and closely-spaced observations of auroral radio absorption—I

Hargreaves, J. K.

doi:10.1016/0032-0633(69)90168-8

Cited by 27 publications

(2 citation statements)

References 14 publications

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“…The effect could be due (i) to a seasonal difference in electron precipitation and/or in the atmospheric response to the precipitation, (ii) to a relative shift in the position of the occurrence zone, or to a combination of these factors. A subsequent investigation using spaced riometers at L∼7 (Hargreaves, 1969b) suggested that both kinds of cause played some part at stations near the latitude of peak occurrence. The situation regarding higher latitudes has never been resolved, however.…”

Section: Introductionmentioning

confidence: 97%

Seasonal variations in the incidence of auroral radio absorption events at very high latitude, and the influence of the magnetotail

Hargreaves

2007

Ann. Geophys.

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Abstract.A statistical analysis has been made of the incidence of auroral radio absorption events at South Pole, and of its dependence on basic geophysical parameters such as season, time of day, and magnetic activity level. It is found that at low and moderate levels of activity the incidence of events in the winter season is at least twice that in the summer. However, at high activity no events at all occurred during the local summer night, which appears to be explicable as the effect of the magnetotail and the consequent distortion of the magnetosphere when the southern polar region is tilted strongly towards the Sun. Previous results from even higher latitudes show the effect in an even more exaggerated form, in that both the day and night periods of absorption activity exhibit strong seasonal variations.

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Section: Introductionmentioning

confidence: 97%

Seasonal variations in the incidence of auroral radio absorption events at very high latitude, and the influence of the magnetotail

Hargreaves

2007

Ann. Geophys.

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“…0148-0227/95JA-03125 $05.00 a coarse mapping of the absorption intensities across the sky. Such systems have provided basic information about the spatial distributions and the dynamical properties of energetic particle precipitation during substorm activity [e.g., Ecklund and Hargreaves, 1968;Hargreaves, 1969, Basic recorded data are 1-s samples of the cosmic noise power received in each of the 49 beams. From these data, and the quiet day (QD) reference intensities, the ionospheric absorption intensities can be calculated each second for each beam separately.…”

Section: Introductionmentioning

confidence: 99%

High‐latitude daytime absorption spike events

Stauning¹,

Rosenberg²

1996

J. Geophys. Res.

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Imaging riometer observations of cosmic noise absorption intensities have revealed a new class of ionospheric radiowave absorption events, the high‐latitude daytime absorption spike events. The occurrences have been examined on the basis of imaging riometer observations from Sondrestrom at an invariant latitude of 73.7°. Representative examples are presented in this report. The spike absorption events, typically, have durations of 1–2 min, and are limited in spatial extent to a region of typical dimensions of 50–100 km. They are rather weak, typically 0.2–0.3 dB, rarely up to l dB at the observing frequency of 38 MHz. Their local magnetic signatures are weak, there is no clear relation to the planetary magnetic activity level (Kp) or to specific interplanetary field variations. The bulk of these events occur at or within a few degrees equatorward of the convection reversal boundary at the afternoon convection cell for typical two‐cell polar ionospheric convection patterns. We suggest that the absorption events relate to the sudden precipitation of high‐energy (30–300 keV) magnetospheric electrons. It is further suggested that the precipitation mechanism for a major part of the afternoon cases is associated with dynamic inverted‐V potential structures developed through a magnetosphere‐ionosphere feedback process acting through near‐saturated upward region 1 field‐aligned currents at the afternoon convection reversal. The consequences derived from the suggested mechanism match very well the observed characteristics of absorption spike events.

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Radio Absorption in Auroral Region

Hargreaves

2015

Auroral Dynamics and Space Weather

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Conjugate and closely-spaced observations of auroral radio absorption—I

Cited by 27 publications

References 14 publications

Seasonal variations in the incidence of auroral radio absorption events at very high latitude, and the influence of the magnetotail

Seasonal variations in the incidence of auroral radio absorption events at very high latitude, and the influence of the magnetotail

High‐latitude daytime absorption spike events

Radio Absorption in Auroral Region

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