Characteristics of night-time absorption spike events

Aminaei, A.; Honary, F.; Kavanagh, A. J.; Spanswick, E.; Viljanen, A.

doi:10.5194/angeo-24-1887-2006

Cited by 14 publications

(24 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The resulting distribution of spikes is centered around the −2 hours MLT. A similar statistical result was also obtained by Aminaei et al [2006]. The comparison with the in situ electron injection distribution given by Thomsen et al [2001] yielded a puzzling difference: the peak of the in situ electron injection is displaced by about 3 hours MLT from that of the riometer spikes.…”

Section: Riometer Signatures Of Substorm Electron Injectionsupporting

confidence: 76%

Azimuthal structures of substorm electron injection and their signatures in riometer observations

et al. 2007

Self Cite

View full text Add to dashboard Cite

[1] We propose a theoretical model to investigate the effects of the curvature/gradient (c/g) drift and the finite azimuthal extent of the dipolarization region on the electron injection process associated with the substorm dipolarization. We study the azimuthal structure of high-energy (>30 keV) electron precipitation flux and compare the result with riometer observations. We are able to reproduce three basic archetypes of riometer responses to substorms, namely, the spike, dispersionless injection, and dispersed injection events catalogued in previous observations. The electron injection near the duskward edge of the dipolarization region is most subject to azimuthal c/g drift loss, appearing in riometer observations as the ''spike'' feature. The ''dispersionless injection'' response is seen inside the dipolarization region but some distance away from its western border: or, alternatively, when the substorm has a rapid westward expansion, so that the gain and loss of electrons from the duskside and dawnside of a dipolarizing flux tube roughly balance. The ''dispersed injection'' feature is seen east of the dipolarization region. Our theory successfully explains the statistical differences in terms of magnetic local time location and peak intensity between spikes and injection events. Through the substorm event on 23 May 1998 we demonstrate that our theoretical predictions of riometer responses are very consistent with the observations. We highlight the potential of riometers in resolving the azimuthal extent and evolution of the dipolarization region, which provides a new ground-based technique of remote sensing the substorm process.

show abstract

Section: Riometer Signatures Of Substorm Electron Injectionsupporting

confidence: 76%

Azimuthal structures of substorm electron injection and their signatures in riometer observations

et al. 2007

Self Cite

View full text Add to dashboard Cite

show abstract

“…defined by solar radiation only) has been found to vary up to an order of magnitude between solar minimum and maximum (Kirkwood, 1993). Aminaei et al (2006) have showed that occurrence rate and amplitude of spikes in riometer data, which are associated with auroral particle precipitation, change by 14% and 1 dB, respectively, from solar minimum to solar maximum. Because the diurnal curves in Fig.…”

Section: Diurnal Pmse Variationsmentioning

confidence: 97%

Polar mesosphere summer echoes with ESRAD, Kiruna, Sweden: Variations and trends over 1997–2008

Smirnova

Belova

Kirkwood

et al. 2010

Journal of Atmospheric and Solar-Terrestrial Physics

View full text Add to dashboard Cite

“…The spike event also displays fine structure similar to magnetic Pi pulsations suggesting a common source region for the modulation (e.g. Hargreaves et al, 2001;Aminaei et al, 2006).…”

Section: Introductionmentioning

confidence: 96%

Energetic electron precipitation during sawtooth injections

Kavanagh

Donovan

et al. 2007

Ann. Geophys.

Self Cite

View full text Add to dashboard Cite

Abstract. We present simultaneous riometer observations of cosmic noise absorption in the nightside and dawn-noon sectors during sawtooth particle injections during 18 April 2002. Energetic electron precipitation (>30 keV) is a feature of magnetospheric substorms and cosmic radio noise absorption acts as a proxy for qualitatively measuring this precipitation. This event provides an opportunity to compare the absorption that accompanies periodic electron injections with the accepted paradigm of substorm-related absorption. We consider whether the absorption is consistent with the premise that these injections are quasi-periodic substorms and study the effects of sustained activity on the level of precipitation. Four consecutive electron injection events have been identified from the LANL (Los Alamos National Laboratory) geosynchronous data; the first two showing that additional activity can occur within the 2-4 h sawtooth periodicity. The first three events have accompanying absorption on the nightside that demonstrate good agreement with the expected pattern of substorm-absorption: discrete spike events with poleward motion at the onset followed by equatorward moving structures and more diffuse absorption, correlated with optical observations. Dayside absorption is linked to gradient-curvature drifting electrons observed at geostationary orbit and it is shown that low fluxes can lead to a lack of absorption as precipitation is suppressed; precipitation begins when the drifting electron flux surpasses some critical level following continuous injections of electrons from the magnetotail. In addition it is shown that the apparent motion of absorption determined from an azimuthal chain of riometers exhibits an acceleration that may be indicative of an energisation of the drifting electron population.

show abstract

Characteristics of night-time absorption spike events

Cited by 14 publications

References 30 publications

Azimuthal structures of substorm electron injection and their signatures in riometer observations

Azimuthal structures of substorm electron injection and their signatures in riometer observations

Polar mesosphere summer echoes with ESRAD, Kiruna, Sweden: Variations and trends over 1997–2008

Energetic electron precipitation during sawtooth injections

Contact Info

Product

Resources

About