Interplanetary Magnetic Fields and Magnetospheric Phenomena: Dependence of Polar Cap Magnetic Fields on the Northward Component of the IMF

2013 ◽  
pp. 608-616
Author(s):  
Kiyoshi Maezawa
Keyword(s):  
Magnetic Fields ◽  
Polar Cap ◽  
Interplanetary Magnetic Fields ◽  
The Imf

Cosmic-ray fluctuations and interplanetary magnetic fields

1993 ◽  
Vol 199 (1) ◽  
pp. 125-132 ◽  
Author(s):  
K. Kudela ◽  
M. Slivka ◽  
M. Stehl�k ◽  
A. Geranios
Keyword(s):  
Magnetic Fields ◽  
Cosmic Ray ◽  
Interplanetary Magnetic Fields

scholarly journals IMF effect on the polar cap contraction and expansion during a period of substorms

2013 ◽  
Vol 31 (6) ◽  
pp. 1021-1034 ◽  
Author(s):  
A. T. Aikio ◽  
T. Pitkänen ◽  
I. Honkonen ◽  
M. Palmroth ◽  
O. Amm
Keyword(s):  
Recovery Phase ◽  
Bow Shock ◽  
Polar Cap ◽  
Reconnection Rate ◽  
Early Recovery ◽  
Mhd Simulation ◽  
Expansion Phase ◽  
Contraction And Expansion ◽  
Good Agreement ◽  
The Imf

Abstract. The polar cap boundary (PCB) location and motion in the nightside ionosphere has been studied by using measurements from the EISCAT radars and the MIRACLE magnetometers during a period of four substorms on 18 February 2004. The OMNI database has been used for observations of the solar wind and the Geotail satellite for magnetospheric measurements. In addition, the event was modelled by the GUMICS-4 MHD simulation. The simulation of the PCB location was in a rather good agreement with the experimental estimates at the EISCAT longitude. During the first three substorm expansion phases, neither the local observations nor the global simulation showed any poleward motions of the PCB, even though the electrojets intensified. Rapid poleward motions of the PCB took place only in the early recovery phases of the substorms. Hence, in these cases the nightside reconnection rate was locally higher in the recovery phase than in the expansion phase. In addition, we suggest that the IMF Bz component correlated with the nightside tail inclination angle and the PCB location with about a 17-min delay from the bow shock. By taking the delay into account, the IMF northward turnings were associated with dipolarizations of the magnetotail and poleward motions of the PCB in the recovery phase. The mechanism behind this effect should be studied further.

Transport of charged particle pulses in interplanetary magnetic fields

1995 ◽  
Vol 45 (9) ◽  
pp. 767-775
Author(s):  
Y. I. Fedorov ◽  
B. A. Shakhov ◽  
M. Stehlík
Keyword(s):  
Charged Particle ◽  
Magnetic Fields ◽  
Interplanetary Magnetic Fields

scholarly journals Magnetosonic Mach number dependence of the efficiency of reconnection between planetary and interplanetary magnetic fields

2009 ◽  
Vol 114 (A7) ◽  
pp. n/a-n/a ◽  
Author(s):  
A. Grocott ◽  
S. V. Badman ◽  
S. W. H. Cowley ◽  
S. E. Milan ◽  
J. D. Nichols ◽  
...  
Keyword(s):  
Mach Number ◽  
Magnetic Fields ◽  
Interplanetary Magnetic Fields

scholarly journals Global characteristics of auroral Hall currents derived from the Swarm constellation: dependences on season and IMF orientation

2017 ◽  
Vol 35 (6) ◽  
pp. 1249-1268 ◽  
Author(s):  
Tao Huang ◽  
Hermann Lühr ◽  
Hui Wang
Keyword(s):  
Magnetic Field ◽  
Hall Current ◽  
Flow Direction ◽  
Magnetic Activity ◽  
The Novel ◽  
Polar Cap ◽  
Magnetic Field Data ◽  
Electrojet Current ◽  
Wind Input ◽  
The Imf

Abstract. On the basis of field-aligned currents (FACs) and Hall currents derived from high-resolution magnetic field data of the Swarm constellation, the average characteristics of these two current systems in the auroral regions are comprehensively investigated by statistical methods. This is the first study considering both current types determined simultaneously by the same spacecraft in both hemispheres. The FAC distribution, derived from the novel Swarm dual-spacecraft approach, reveals the well-known features of Region 1 (R1) and Region 2 (R2) FACs. At high latitudes, Region 0 (R0) FACs appear on the dayside. Their flow direction, up or down, depends on the orientation of the interplanetary magnetic field (IMF) By component. Of particular interest is the distribution of auroral Hall currents. The prominent auroral electrojets are found to be closely controlled by the solar wind input, but we find no dependence of their intensity on the IMF By orientation. The eastward electrojet is about 1.5 times stronger in local summer than in winter. Conversely, the westward electrojet shows less dependence on season. As to higher latitudes, part of the electrojet current is closed over the polar cap. Here the seasonal variation of conductivity mainly controls the current density. During local summer of the Northern Hemisphere, there is a clear channeling of return currents over the polar cap. For positive (negative) IMF By a dominant eastward (westward) Hall current circuit is formed from the afternoon (morning) electrojet towards the dawn side (dusk side) polar cap return current. The direction of polar cap Hall currents in the noon sector depends directly on the orientation of the IMF By. This is true for both signs of the IMF Bz component. Comparable Hall current distributions can be observed in the Southern Hemisphere but for opposite IMF By signs. Around the midnight sector the westward substorm electrojet is dominating. As expected, it is highly dependent on magnetic activity, but it shows only little response to season and IMF By polarity. An important finding is that all the IMF By dependences of FACs and Hall currents practically disappear in the dark winter hemisphere.

scholarly journals Extremely intense (SML ≤–2500 nT) substorms: isolated events that are externally triggered?

2015 ◽  
Vol 33 (5) ◽  
pp. 519-524 ◽  
Author(s):  
B. T. Tsurutani ◽  
R. Hajra ◽  
E. Echer ◽  
J. W. Gjerloev
Keyword(s):  
Solar Wind ◽  
Magnetic Fields ◽  
Magnetic Storm ◽  
Solar Wind Plasma ◽  
Magnetic Storms ◽  
Input Energy ◽  
Stored Energy ◽  
Ionospheric Currents ◽  
Interplanetary Magnetic Fields ◽  
Very High

Abstract. We examine particularly intense substorms (SML ≤–2500 nT), hereafter called "supersubstorms" or SSS events, to identify their nature and their magnetic storm dependences. It is found that these intense substorms are typically isolated events and are only loosely related to magnetic storms. SSS events can occur during super (Dst ≤–250 nT) and intense (−100 nT ≥ Dst >–250) magnetic storms. SSS events can also occur during nonstorm (Dst ≥–50 nT) intervals. SSSs are important because the strongest ionospheric currents will flow during these events, potentially causing power outages on Earth. Several SSS examples are shown. SSS events appear to be externally triggered by small regions of very high density (~30 to 50 cm−3) solar wind plasma parcels (PPs) impinging upon the magnetosphere. Precursor southward interplanetary magnetic fields are detected prior to the PPs hitting the magnetosphere. Our hypothesis is that these southward fields input energy into the magnetosphere/magnetotail and the PPs trigger the release of the stored energy.

scholarly journals Anomalous magnetosheath flows and distorted subsolar magnetopause for radial interplanetary magnetic fields

2009 ◽  
Vol 36 (18) ◽  
Author(s):  
J.-H. Shue ◽  
J.-K. Chao ◽  
P. Song ◽  
J. P. McFadden ◽  
A. Suvorova ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Interplanetary Magnetic Fields

scholarly journals Effects of the Crustal Magnetic Fields and Changes in the IMF Orientation on the Magnetosphere of Mars: MAVEN Observations and LatHyS Results

2018 ◽  
Vol 123 (7) ◽  
pp. 5315-5333 ◽  
Author(s):  
N. Romanelli ◽  
R. Modolo ◽  
F. Leblanc ◽  
J-Y. Chaufray ◽  
S. Hess ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
The Imf
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