scholarly journals Initial results of high-latitude magnetopause and low-latitude flank flux transfer events from 3 years of Cluster observations

2005 ◽  
Vol 110 (A11) ◽  
Author(s):  
Y. L. Wang ◽  
R. C. Elphic ◽  
B. Lavraud ◽  
M. G. G. T. Taylor ◽  
J. Birn ◽  
...  
Keyword(s):  
High Latitude ◽  
Low Latitude ◽  
Flux Transfer Events ◽  
Flux Transfer ◽  
Initial Results

scholarly journals Cluster observations of bounday layer structure and a flux transfer event near the cusp

2005 ◽  
Vol 23 (7) ◽  
pp. 2605-2620 ◽  
Author(s):  
R. C. Fear ◽  
A. N. Fazakerley ◽  
C. J. Owen ◽  
A. D. Lahiff ◽  
E. A. Lucek ◽  
...  
Keyword(s):  
Boundary Layer ◽  
High Latitude ◽  
Layer Structure ◽  
Normal Component ◽  
Transfer Event ◽  
Flux Transfer Events ◽  
Magnetic Signatures ◽  
Northern High Latitude ◽  
Flux Transfer ◽  
The Magnetic Field

Abstract. On the 25th January 2002 between 10:00 and 12:00 UT, the four Cluster spacecraft passed through the northern high-latitude cusp, the dayside magnetosphere and into the magnetosheath in a linear formation. In the magnetosphere the PEACE electron spectrometers on the four spacecraft all observed a series of transient bursts of magnetosheath-like plasma, but without bipolar magnetic signatures in the magnetopause normal component as might be expected if the plasma had been injected by transient reconnection (flux transfer events – FTEs). Reordering the data using the magnetopause transition parameter reveals that these plasma observations, the related variations in the magnetic field and the balance of magnetic and thermal gas pressures are consistent with transient entries into a stable high-latitude boundary layer structure. However, once some of the spacecraft entered the magnetosheath, FTE signatures were observed outside the magnetopause at the same time as some of the boundary layer entries occurred at the other spacecraft inside. Thus, (a) the lack of a bipolar BN signature is inconsistent with the traditional picture of a magnetospheric FTE, and (b) the cause of the observed entry of the spacecraft into the boundary layer (pressure pulse or passing magnetosheath FTE) can only be determined by spacecraft observations in the magnetosheath. Keywords. Magnetospheric physics (Magnetopause, cusp and bondary layers; Solar wind- magnetosphere interactions; Magnetosheath)

scholarly journals Cluster observations of quasi-periodic impulsive signatures in the dayside northern lobe: High-latitude flux transfer events?

2004 ◽  
Vol 109 (A2) ◽  
Author(s):  
S. M. Thompson ◽  
M. G. Kivelson ◽  
K. K. Khurana ◽  
A. Balogh ◽  
H. Réme ◽  
...  
Keyword(s):  
High Latitude ◽  
Flux Transfer Events ◽  
Flux Transfer

scholarly journals Simultaneous observations of magnetopause flux transfer events and of their associated signatures at ionospheric altitudes

2004 ◽  
Vol 22 (6) ◽  
pp. 2181-2199 ◽  
Author(s):  
K. A. McWilliams ◽  
G. J. Sofko ◽  
T. K. Yeoman ◽  
S. E. Milan ◽  
D. G. Sibeck ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Southern Hemisphere ◽  
High Latitude ◽  
Field Conditions ◽  
Transfer Event ◽  
Flux Transfer Events ◽  
Subsolar Point ◽  
Reconnection Site ◽  
Flux Transfer

Abstract. An extensive variety of instruments, including Geotail, DMSP F11, SuperDARN, and IMP-8, were monitoring the dayside magnetosphere and ionosphere between 14:00 and 18:00 UT on 18 January 1999. The location of the instruments provided an excellent opportunity to study in detail the direct coupling between the solar wind, the magnetosphere, and the ionosphere. Flux transfer events were observed by Geotail near the magnetopause in the dawn side magnetosheath at about 4 magnetic local time during exclusively northward interplanetary magnetic field conditions. Excellent coverage of the entire dayside high-latitude ionosphere was achieved by the Northern Hemisphere SuperDARN radars. On the large scale, temporally and spatially, the dayside magnetosphere convection remained directly driven by the interplanetary magnetic field, despite the highly variable interplanetary magnetic field conditions, including long periods of northward field. The SuperDARN radars in the dawn sector also measured small-scale temporally varying convection velocities, which are indicative of flux transfer event activity, in the vicinity of the magnetic footprint of Geotail. DMSP F11 in the Southern Hemisphere measured typical cusp precipitation simultaneously with and magnetically conjugate to a single flux transfer event signature detected by Geotail. A study of the characteristics of the DMSP ion spectrogram revealed that the source plasma from the reconnection site originated downstream of the subsolar point. Detailed analyses of locally optimised coordinate systems for individual flux transfer events at Geotail are consistent with a series of flux tubes protruding from the magnetopause, and originating from a high-latitude reconnection site in the Southern Hemisphere. This high-latitude reconnection site agrees with plasma injected away from the subsolar point. This is the first simultaneous and independent determination from ionospheric and space-based data of the location of magnetic reconnection.

scholarly journals Pulsed flows observed during an interval of prolonged northward IMF

2005 ◽  
Vol 23 (4) ◽  
pp. 1207-1225 ◽  
Author(s):  
G. Provan ◽  
M. Lester ◽  
A. Grocott ◽  
S. W. H. Cowley
Keyword(s):  
Northern Hemisphere ◽  
High Latitude ◽  
Low Latitude ◽  
Radar Backscatter ◽  
Flux Transfer Events ◽  
Equatorward Boundary ◽  
Dayside Magnetopause ◽  
Open Flux ◽  
Lobe Reconnection ◽  
The Imf

Abstract. On the 22 December 2002 the interplanetary magnetic field (IMF) was directed northwards for more than 12h. The Northern and Southern Hemisphere SuperDARN radars were used to study global high-latitude convection during this interval, complemented by data from the ACE and DMSP F13 spacecraft. The relative magnitudes of the IMF By and Bz components varied during this period. When the magnitude of the By component was comparable with or dominated the Bz component, signatures of simultaneous low-latitude and lobe reconnection were observed. Specifically two "standard" merging cells were observed in both hemispheres. In the Northern Hemisphere a high-latitude lobe cell was observed within the dusk merging cell, and there was also evidence of a narrow viscous cell located equatorward of this lobe cell. We observed the ionospheric signatures of flux transfer events (FTEs) in both the Northern and Southern Hemispheres, occurring with a periodicity of ~15min. In the Northern Hemisphere the FTEs were associated with a stepwise equatorward progression of the equatorward boundary of radar backscatter on the dayside. When the IMF Bz component was predominantly greater than the IMF By component, we observed a four-cell convection pattern in the Northern Hemisphere, with pulses of reverse reconnection and an associated stepwise poleward retraction of the equatorward boundary of radar backscatter occurring every ~25min. These observations are consistent with pulsed lobe reconnection occurring in both hemispheres, closing open flux and adding closed flux to the dayside magnetopause. So, during this northward IMF interval the location of the sites of reconnection between the IMF and the Earth's magnetosphere, and thus the form of reconnection process, varied with changing IMF conditions. However, the reconnection remained pulsed, with lobe-only reconnection having a significantly longer periodicity compared with simultaneous lobe and low-latitude reconnection.

scholarly journals Flux transfer events on the high-latitude magnetopause: Interball-1 observations

2005 ◽  
Vol 23 (11) ◽  
pp. 3549-3559 ◽  
Author(s):  
D. G. Sibeck ◽  
G. I. Korotova ◽  
V. Petrov ◽  
V. Styazhkin ◽  
T. J. Rosenberg
Keyword(s):  
Magnetic Field ◽  
High Latitude ◽  
Pressure Gradients ◽  
Field Orientation ◽  
Flux Transfer Events ◽  
Statistical Studies ◽  
Flux Transfer ◽  
Statistical Survey ◽  
Almost All ◽  
Marked Tendency

Abstract. We present case and statistical studies of flux transfer events (FTEs) observed by Interball-1 on the high-latitude magnetopause. The case studies provide observations of FTEs in the cusp during periods of southward interplanetary magnetic field (IMF) orientation and on the magnetopause poleward of the cusp during periods of strongly northward IMF orientation. We interpret the former in terms of reconnection on the equatorial magnetopause and subsequent antisunward motion of FTEs into the cusps. We interpret the latter in terms of bursty antiparallel merging on the high-latitude magnetopause. A statistical survey demonstrates that events observed equatorward of the cusp show a marked tendency to occur for antiparallel (northward) magnetospheric and (southward) magnetosheath magnetic field orientations, whereas events observed poleward of the cusps tend to occur for either strongly parallel or antiparallel configurations. We suggest that this discrepancy implies that events observed poleward of the cusps originate both locally and on the equatorial magnetopause. Finally, we use the sense of the bipolar signature and the prevailing magnetic field orientation to demonstrate that almost all events move antisunward, i.e. that at these latitudes pressure gradients determine the motion of FTEs and not magnetic curvature forces.

scholarly journals Cluster observations of “crater” flux transfer events at the dayside high-latitude magnetopause

2008 ◽  
Vol 113 (A7) ◽  
pp. n/a-n/a ◽  
Author(s):  
C. J. Owen ◽  
A. Marchaudon ◽  
M. W. Dunlop ◽  
A. N. Fazakerley ◽  
J.-M. Bosqued ◽  
...  
Keyword(s):  
High Latitude ◽  
Flux Transfer Events ◽  
Flux Transfer

A Study of Orientation and Motion of Flux Transfer Events Observed at High-Latitude Dayside Magnetopause

2005 ◽  
Vol 48 (6) ◽  
pp. 1307-1315 ◽  
Author(s):  
Li YAO ◽  
Shao-Liang LIU ◽  
Shu-Ping JIN ◽  
Zhen-Xing LIU ◽  
Jian-Kui SHI ◽  
...  
Keyword(s):  
High Latitude ◽  
Flux Transfer Events ◽  
Dayside Magnetopause ◽  
Flux Transfer

scholarly journals First simultaneous observations of flux transfer events at the high-latitude magnetopause by the Cluster spacecraft and pulsed radar signatures in the conjugate ionosphere by the CUTLASS and EISCAT radars

2001 ◽  
Vol 19 (10/12) ◽  
pp. 1491-1508 ◽  
Author(s):  
J. A. Wild ◽  
S. W. H. Cowley ◽  
J. A. Davies ◽  
H. Khan ◽  
M. Lester ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Boundary Layer ◽  
High Latitude ◽  
Polar Ionosphere ◽  
Related Field ◽  
Flux Transfer Events ◽  
Direct Demonstration ◽  
Magnetic Perturbations ◽  
Flux Transfer ◽  
Pass Through

Abstract. Cluster magnetic field data are studied during an outbound pass through the post-noon high-latitude magnetopause region on 14 February 2001. The onset of several minute perturbations in the magnetospheric field was observed in conjunction with a southward turn of the interplanetary magnetic field observed upstream by the ACE spacecraft and lagged to the subsolar magnetopause. These perturbations culminated in the observation of four clear magnetospheric flux transfer events (FTEs) adjacent to the magnetopause, together with a highly-structured magnetopause boundary layer containing related field features. Furthermore, clear FTEs were observed later in the magnetosheath. The magnetospheric FTEs were of essentially the same form as the original "flux erosion events" observed in HEOS-2 data at a similar location and under similar interplanetary conditions by Haerendel et al. (1978). We show that the nature of the magnetic perturbations in these events is consistent with the formation of open flux tubes connected to the northern polar ionosphere via pulsed reconnection in the dusk sector magnetopause. The magnetic footprint of the Cluster spacecraft during the boundary passage is shown to map centrally within the fields-of-view of the CUTLASS SuperDARN radars, and to pass across the field-aligned beam of the EISCAT Svalbard radar (ESR) system. It is shown that both the ionospheric flow and the backscatter power in the CUTLASS data pulse are in synchrony with the magnetospheric FTEs and boundary layer structures at the latitude of the Cluster footprint. These flow and power features are subsequently found to propagate poleward, forming classic "pulsed ionospheric flow" and "poleward-moving radar auroral form" structures at higher latitudes. The combined Cluster-CUTLASS observations thus represent a direct demonstration of the coupling of momentum and energy into the magnetosphere-ionosphere system via pulsed magnetopause reconnection. The ESR observations also reveal the nature of the structured and variable polar ionosphere produced by the structured and time-varying precipitation and flow.Key words. Ionosphere (auroral ionosphere) Magentospheric physics (magnetopause, cusp and boundary layers; magnetosphere-ionosphere interactions)

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