Field-aligned current systems in the magnetospheric ground state

1998 ◽  
Vol 103 (A4) ◽  
pp. 6853-6869 ◽  
Author(s):  
Masakazu Watanabe ◽  
Takesi Iijima ◽  
Masayuki Nakagawa ◽  
Thomas A. Potemra ◽  
Laurence J. Zanetti ◽  
...  
Keyword(s):  
Ground State ◽  
Field Aligned Current ◽  
Current Systems

Altitudinal comparison of dayside field-aligned current signatures by Viking and DMSP-F7: Intermediate-scale field-aligned current systems

1996 ◽  
Vol 101 (A7) ◽  
pp. 15297-15310 ◽  
Author(s):  
S. Ohtani ◽  
L. G. Blomberg ◽  
P. T. Newell ◽  
M. Yamauchi ◽  
T. A. Potemra ◽  
...  
Keyword(s):  
Intermediate Scale ◽  
Scale Field ◽  
Field Aligned Current ◽  
Current Signatures ◽  
Current Systems

scholarly journals A comparison of small‐scale magnetic fluctuations in the Region 1 and 2 field‐aligned current systems

2017 ◽  
Vol 122 (3) ◽  
pp. 3277-3290 ◽  
Author(s):  
J. Wu ◽  
M. S. Bryant ◽  
C. G. Ridley ◽  
Y. Shen ◽  
L. Yang ◽  
...  
Keyword(s):  
Small Scale ◽  
Magnetic Fluctuations ◽  
Field Aligned Current ◽  
Current Systems

scholarly journals Cluster and Double Star multipoint observations of a plasma bubble

2009 ◽  
Vol 27 (2) ◽  
pp. 725-743 ◽  
Author(s):  
A. P. Walsh ◽  
A. N. Fazakerley ◽  
A. D. Lahiff ◽  
M. Volwerk ◽  
A. Grocott ◽  
...  
Keyword(s):  
High Speed ◽  
Double Star ◽  
Plasma Bubble ◽  
Flux Transport ◽  
Flux Tubes ◽  
Plasma Bubbles ◽  
Direct Observations ◽  
Mhd Simulations ◽  
Field Aligned Current ◽  
Current Systems

Abstract. Depleted flux tubes, or plasma bubbles, are one possible explanation of bursty bulk flows, which are transient high speed flows thought to be responsible for a large proportion of flux transport in the magnetotail. Here we report observations of one such plasma bubble, made by the four Cluster spacecraft and Double Star TC-2 around 14:00 UT on 21 September 2005, during a period of southward, but BY-dominated IMF. In particular the first direct observations of return flows around the edges of a plasma bubble, and the first observations of plasma bubble features within 8 RE of the Earth, consistent with MHD simulations (Birn et al., 2004) are presented. The implications of the presence of a strong BY in the IMF and magnetotail on the propagation of the plasma bubble and development of the associated current systems in the magnetotail and ionosphere are discussed. It is suggested that a strong BY can rotate the field aligned current systems at the edges of the plasma bubble away from its duskward and dawnward flanks.

scholarly journals Characteristics of the terrestrial field-aligned current system

2011 ◽  
Vol 29 (10) ◽  
pp. 1713-1729 ◽  
Author(s):  
J. W. Gjerloev ◽  
S. Ohtani ◽  
T. Iijima ◽  
B. Anderson ◽  
J. Slavin ◽  
...  
Keyword(s):  
Large Scale ◽  
Current System ◽  
Scale Size ◽  
Terrestrial Magnetosphere ◽  
Field Aligned Current ◽  
Low Altitude ◽  
String Formation ◽  
Energy And Momentum ◽  
Current Systems ◽  
The Magnetic Field

Abstract. We present the first ever comprehensive statistical study of the spatiotemporal characteristics of field-aligned currents in the terrestrial magnetosphere-ionosphere system using multi point measurements. We determine how the FAC density, variability and scale size are coupled. The three ST 5 satellites were in a pearls-on-a-string formation making measurements of the magnetic field with variable inter-spacecraft separations ranging from a few seconds to about 10 min. More than 4700 sets of satellite passes are analyzed using a robust correlation analysis aimed at determining the variability of the FAC system as a function of scale size and satellite spacing. We find significant differences between the FAC characteristics on the dayside and on the nightside in terms of dynamics of the current systems. On the dayside the FAC characteristics are found to be independent of IMF Bz and geomagnetic activity while the nightside indicates increased variability during disturbed conditions. The boundary separating highly and poorly correlated FACs can be fitted by a linear line for satellite separations shorter than 60 s (dayside) and 160 s (nightside). We interpret this as the dayside and nightside magnetospheric reconfiguration times respectively. For times exceeding this the FAC characteristics are suggested to be controlled by the solar wind (dayside) and plasma sheet (nightside) dynamics. Finally, the characteristics of FAC system with scale sizes larger than ~200 km (at ionospheric altitude) appear to be stable and repeatable on time scales of the order of a minute (i.e. comparable to the low-altitude orbiting satellite's traverse time across the auroral belt). In this sense, our results effectively validate the Iijima and Potemra (1978) assumption that on average the large-scale currents with scale sizes of the Region1 and Region2 are quasi-persistently significant in the transport of energy and momentum between the magnetosphere and the ionosphere.

scholarly journals The UV aurora and ionospheric flows during flux transfer events

2001 ◽  
Vol 19 (2) ◽  
pp. 179-188 ◽  
Author(s):  
D. A. Neudegg ◽  
S. W. H. Cowley ◽  
K. A. McWilliams ◽  
M. Lester ◽  
T. K. Yeoman ◽  
...  
Keyword(s):  
Ultra Violet ◽  
Spectral Width ◽  
Hf Radar ◽  
Electron Precipitation ◽  
Flux Transfer Events ◽  
Optical Feature ◽  
Geomagnetic Fields ◽  
Field Aligned Current ◽  
Flux Transfer ◽  
Current Systems

Abstract. Far Ultra Violet (FUV) signatures in the polar ionosphere during a period of magnetopause reconnection are compared with ionospheric flows measured in the cusp ‘throat’ and dusk cell by the CUTLASS Hankasalmi HF radar. Regions of peak FUV emission in the 130.4 nm and 135.6 nm range, observed by the Polar spacecraft’s VIS Earth Camera, consistently lie at the turning point of the flows from the dusk cell, poleward into the throat, and at the equatorward edge of the region of high and varied radar spectral-width associated with the cusp. The Equator-S spacecraft was near the magnetopause at the time of the ionospheric observations and geomagnetically conjugate with the region of ionosphere observed by the radar. Flux transfer events (FTEs), suggestive of bursty reconnection between the IMF and geomagnetic fields, were observed by Equator-S prior to and during the periods of high FUV emission. Enhanced poleward ionospheric flow velocities in the polar cusp region, previously shown to be associated with bursty reconnection, consistently lie poleward of the enhanced FUV optical feature. The enhanced optical feature is consistent with the expected position of the largest upward region 1 field-aligned current, associated with electron precipitation, on the dusk edge of the merging gap. The optical feature moves duskward and equatorward during the course of the reconnection sequence, consistent with expansion of the merging line and the polar cap with newly added open magnetic flux by the FTEs. The DMSP F14 spacecraft passed through the enhanced FUV region and measured strong, structured electron precipitation far greater than in the adjacent regions.Key words. Magnetospheric physics (current systems; magnetopause, cusp and boundary layers; magnetosphere-ionosphere interactions)

Preliminary results from Project Waterhole — an auroral modification experiment

1981 ◽  
Vol 59 (8) ◽  
pp. 1175-1182 ◽  
Author(s):  
B. A. Whalen ◽  
A. W. Yau ◽  
F. Creutzberg ◽  
R. L. Gattinger ◽  
F. R. Harris ◽  
...  
Keyword(s):  
Energetic Electron ◽  
Electron Precipitation ◽  
Sounding Rocket ◽  
Plasma Diagnostic ◽  
E Region ◽  
Field Aligned Current ◽  
Field Lines ◽  
Plasma Depletion ◽  
Current Systems ◽  
By Products

A sounding rocket carrying 100 kg of high explosives and plasma diagnostic instrumentation was launched from Churchill Research Range on 6 April 1980 over a premidnight auroral arc. The object of the experiment was to produce an ionospheric hole or plasma density depletion near 300 km altitude on field lines connected to an auroral arc. The plasma depletion is produced when the explosive by-products (mostly water) charge-exchange with the ambient O+ ions and then rapidly recombine. It was speculated that the presence of the "hole" would interfere with the field aligned current systems associated with the arc and would in turn perturb the auroral source mechanism. The release occurred about 10 km poleward of the auroral arc fieldlines. As expected, a large ionospheric hole was detected by the rocket-borne plasma sensors. Within a few seconds following the release (a) the energetic electron precipitation observed in the hole dropped to background levels, (b) the luminosity of the auroral arc observed by a ground-based auroral scanning photometer decreased by a factor of two, and (c) the ionospheric E region density below the hole decayed at a rate consistent with a sudden reduction in particle precipitation. The simultaneous onset of these gross changes in electron precipitation coincident with the release strongly suggests a cause and effect relationship and demonstrates the intimate relationship that exists between the state of the ionospheric plasma and the auroral acceleration mechanism.

Four large-scale field-aligned current systems in the dayside high-latitude region

1995 ◽  
Vol 100 (A1) ◽  
pp. 137 ◽  
Author(s):  
S. Ohtani ◽  
T. A. Potemra ◽  
P. T. Newell ◽  
L. J. Zanetti ◽  
T. Iijima ◽  
...  
Keyword(s):  
High Latitude ◽  
Large Scale ◽  
High Latitude Region ◽  
Scale Field ◽  
Large Scale Field ◽  
Latitude Region ◽  
Field Aligned Current ◽  
Current Systems
Sign in / Sign up

Export Citation Format

Share Document