Structure of disturbances in the dayside and nightside ionosphere during periods of negative interplanetary magnetic field <i>B<sub>z</sub></i>

Solovyev, S. I.; Otsuka, Yuichi; Barkova, E. S.; Engebretson, M. J.; Posch, J. L.; Hughes, W. J.; Yumoto, K.; Pilipenko, V. A.

doi:10.1029/1999ja900286

Cited by 25 publications

(23 citation statements)

References 52 publications

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“…In particular, streamers or NS Sun-aligned arcs which peel off the auroral oval and extend to the latitude of the main ionospheric trough will be investigated further using other AWFC events detected with TIGER. It is interesting to note that reported propagation speeds of NS Sun-aligned arcs (Solovyev et al, 1999) and Ps6 pulsations (Saito, 1978) are both comparable to the westward drift speeds measured during our AWFC.…”

Section: Discussionmentioning

confidence: 66%

On the lifetime and extent of an auroral westward flow channel (AWFC) observed during a magnetospheric substorm

Parkinson

Pinnock

et al. 2003

Ann. Geophys.

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Abstract.A −190-nT negative bay in the geomagnetic X component measured at Macquarie Island (−65 • ) showed that an ionospheric substorm occurred during 09:58 to 11:10 UT on 27 February 2000. Signatures of an auroral westward flow channel (AWFC) were observed nearly simultaneously in the backscatter power, LOS Doppler velocity, and Doppler spectral width measured using the Tasman International Geospace Environment Radar (TIGER), a Southern Hemisphere HF SuperDARN radar. Many of the characteristics of the AWFC were similar to those occurring during a polarisation jet (PJ), or subauroral ion drift (SAID) event, and suggest that it may have been a precursor to a fully developed, intense westward flow channel satisfying all of the criteria defining a PJ/SAID. A beamswinging analysis showed that the westward drifts (poleward electric field) associated with the flow channel were very structured in time and space, but the smoothed velocities grew to ∼800 m s −1 (47 mV m −1 ) during the 22-min substorm onset interval 09:56 to 10:18 UT. Maximum westward drifts of >1.3 km s −1 (>77 mV m −1 ) occurred during a ∼5-min velocity spike, peaking at 10:40 UT during the expansion phase. The drifts decayed rapidly to ∼300 m s −1 (18 mV m −1 ) during the 6-min recovery phase interval, 11:04 to 11:10 UT. Overall, the AWFC had a lifetime of 74 min, and was located near −65 • in the evening sector west of the Harang discontinuity. The large westward drifts were confined to a geographic zonal channel of longitudinal extent >20 • (>1.3 h magnetic local time), and latitudinal width ∼2 • . Using a half-width of ∼100 km in latitude, the peak electric potential was >7.7 kV. However, a transient velocity of >3.1 km s −1 with potential >18.4 kV was observed further poleward at the end of the recovery phase. Auroral oval boundaries determined using DMSP measurements suggestCorrespondence to: M. L. Parkinson (m.parkinson@latrobe.edu.au) the main flow channel overlapped the equatorward boundary of the diffuse auroral oval. During the ∼2-h interval following the flow channel, an ∼3 • wide band of scatter was observed drifting slowly toward the west, with speeds gradually decaying to ∼50 m s −1 (3 mV m −1 ). The scatter was observed extending past the Harang discontinuity, and had Doppler signatures characteristic of the main ionospheric trough, implicating the flow channel in the further depletion of F-region plasma. The character of this scatter was in contrast with the character of the scatter drifting toward the east at higher latitude.Key words. Ionosphere (auroral ionosphere; electric fields and currents; ionosphere-magnetospehere interactions) Magnetospheric physics (storms and substorms)

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Section: Discussionmentioning

confidence: 66%

On the lifetime and extent of an auroral westward flow channel (AWFC) observed during a magnetospheric substorm

Parkinson

Pinnock

et al. 2003

Ann. Geophys.

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“…omega bands) most often in the morning sector and sometimes in the midnight sector. Recently, several cases of similar optical phenomena have also been reported in the evening sector (Solovyev et al, 1999).…”

Section: Introductionmentioning

confidence: 91%

“…In the dayside magnetospheric plasma, the necessary pressure gradient driving the interchange instability may take place, for example: i) during the periodic magnetopause oscillation that could lead to the formation of the gap between the central plasma sheet and the low-latitude boundary layer, as is frequently seen in the DMSP data Meng, 1992, 1994); ii) during the periods of northward IMF B z , when the magnetosheath plasma penetrates into the dayside magnetosphere via the reconnection process (Song and Russell, 1992). These possibilities were previously discussed by Lyatsky and Sibeck (1997) and Kozlovsky et al (2003) in connection with the problem of the generation of different kinds of dayside auroras.…”

Section: Possible Scenario For Formation Of Omega Aurorasmentioning

confidence: 99%

Combined optical, EISCAT and magnetic observations of the omega bands/Ps6 pulsations and an auroral torch in the late morning hours: a case study

et al. 2005

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Abstract. We present here the results of multi-instrument observations of auroral torch and Ps6 magnetic pulsations, which are assumed to be the magnetic signature of the spatially periodic optical auroras known as omega bands. Data from TV and ASC cameras in Barentsburg and NyÅlesund, EISCAT radars in Longyearbyen and Tromsø, as well as IMAGE network were used in this study. The auroral phenomenon which was considered differed from that previously discussed, as it occurred both in an unusual place (high latitudes) and at an unusual time (late morning hours). We show that this might occur due to specific conditions in the interplanetary medium, causing the appropriate deformation of the magnetosphere. In such a case, the IMF turned out to be an additional factor in driving the regime of Ps6/omega bands, namely, only by acting together could a substorm onset in the night sector and B z variations result in their generation. Since the presumable source of Ps6/omega bands does not co-locate with convection reversal boundaries, we suggest the interpretation of the phenomena in the frame of the interchange instability instead of the Kelvin-Helmholtz instability that is widely discussed in the literature in connection with omega auroras. Some numerical characteristics of the auroral torch were obtained. We also emphasize to the dark hole in the background luminosity and the shortlived azimuthally-restricted auroral arc, since their appearance could initiate the auroral torch development.

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“…But, during the BBAE the IMF Bz was almost negative, thus it has comparatively less influence on the auroral emission boundary movement during BBAE than the IMF By. Solovyev et al (1999) studied the substorm time (AE∼400 nT) nightside auroral oval during the southward IMF Bz and reported that pre-magnetic-midnight auroral structure shrink to the equatorward edge of the auroral oval, however post-magneticmidnight sectors formed the omega band auroral structure. We observe nearly similar saturation during the BBAE, where nightside auroral oval boundaries shrink to poleward during the substorm and southward IMF Bz in the post-midnight sectors and form some auroral emission pattern like an omega aurora band.…”

Section: Bouncing Boundary Auroral Emissions (Bbae)mentioning

confidence: 99%

The Behaviors of Ionospheric Scintillations Around Different Types of Nightside Auroral Boundaries Seen at the Chinese Yellow River Station, Svalbard

Priyadarshi

Zhang

et al. 2018

Front. Astron. Space Sci.

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Dynamical nightside auroral structures are often observed by the all sky imagers (ASI) at the Chinese Yellow River Station (CYRS) at Ny-Ålesund, Svalbard, located in the polar cap near poleward edge of the nightside auroral oval. The boundaries of the nightside auroral oval are stable during quiet geomagnetic conditions, while they often expand poleward and pass through the overhead area of CYRS during the substorm expansion phase. The motions of these boundaries often give rise to strong disturbances of satellite navigations and communications. Two cases of these auroral boundary motions have been introduced to investigate their associated ionospheric scintillations: one is Fixed Boundary Auroral Emissions (FBAE) with stable and fixed auroral boundaries, and another is Bouncing Boundary Auroral Emissions (BBAE) with dynamical and largely expanding auroral boundaries. Our observations show that the auroral boundaries, identified from the sharp gradient of the auroral emission intensity from the ASI images, were clearly associated with ionospheric scintillations observed by Global Navigation Satellite System (GNSS) scintillation receiver at the CYRS. However, amplitude scintillation (S 4 ) and phase scintillation (σ φ ) respond in an entirely different way in these two cases due to the different generation mechanism as well as different IMF (Interplanetary Magnetic Field) condition. S 4 and σ φ have similar levels around the FBAE, while σ φ was much stronger than S 4 around BBAE. The BBAE were associated with stronger particle precipitation during the substorm expansion phase. IU/IL, appeared to be a good indicator of the poleward moving auroral structures during the BBAE as well as FBAE.

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Structure of disturbances in the dayside and nightside ionosphere during periods of negative interplanetary magnetic field B_z

Cited by 25 publications

References 52 publications

On the lifetime and extent of an auroral westward flow channel (AWFC) observed during a magnetospheric substorm

On the lifetime and extent of an auroral westward flow channel (AWFC) observed during a magnetospheric substorm

Combined optical, EISCAT and magnetic observations of the omega bands/Ps6 pulsations and an auroral torch in the late morning hours: a case study

The Behaviors of Ionospheric Scintillations Around Different Types of Nightside Auroral Boundaries Seen at the Chinese Yellow River Station, Svalbard

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Structure of disturbances in the dayside and nightside ionosphere during periods of negative interplanetary magnetic field Bz

Cited by 25 publications

References 52 publications

On the lifetime and extent of an auroral westward flow channel (AWFC) observed during a magnetospheric substorm

On the lifetime and extent of an auroral westward flow channel (AWFC) observed during a magnetospheric substorm

Combined optical, EISCAT and magnetic observations of the omega bands/Ps6 pulsations and an auroral torch in the late morning hours: a case study

The Behaviors of Ionospheric Scintillations Around Different Types of Nightside Auroral Boundaries Seen at the Chinese Yellow River Station, Svalbard

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Structure of disturbances in the dayside and nightside ionosphere during periods of negative interplanetary magnetic field B_z