Configuration of the magnetosphere‐ionosphere convection system under northward IMF conditions with nonzero IMF By

Tanaka, Takashi

doi:10.1029/1999ja900077

Cited by 71 publications

(164 citation statements)

References 16 publications

(31 reference statements)

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“…The IMF B Y component was closer to zero in the northern hemisphere winter case examined by Watanabe et al [2006]. It would be useful in the future to investigate the interhemispheric convection under even stronger B Y , as Tanaka [1999] suggested that there would be interhemispheric connection between merging cells and lobe cells, resulting from a similar structure to that shown in Figure 10.…”

Section: Summary and Discussionmentioning

confidence: 92%

Interhemispheric observations of dayside convection under northward IMF

et al. 2011

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[1] The reverse convection potential and electric field under northward interplanetary magnetic field (IMF) has been shown to saturate at a larger value in the summer than in the winter. Previous studies of reverse convection under northward IMF have suggested that in the winter hemisphere, much of the reconnection involves "internal reconnection" with over-draped field lines from the summer hemisphere. We present a case study in which reverse convection was simultaneously visible in the northern and southern hemispheres near the northern winter solstice. We use SuperDARN radar velocity measurements to demonstrate that the sunward (reverse) convection along the noon meridian is significantly faster in the summer hemisphere. We also use DMSP energetic particle data to demonstrate that in the winter hemisphere, some of the convection circulates on closed field lines, which is a signature of internal reconnection. These results suggest that internal reconnection is much less effective in transmitting the interplanetary electric field (IEF) into the ionosphere.

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Section: Summary and Discussionmentioning

confidence: 92%

Interhemispheric observations of dayside convection under northward IMF

et al. 2011

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“…It is well known that the most effective process to generate the convection is the reconnection between the IMF and the geomagnetic field both for the southward IMF and the northward IMF [Fairfield and Cahill, 1966;Crooker, 1979;Nishida et al, 1998;Crooker et al, 1998;White et al, 1998;Tanaka, 1999]. Under the northward IMF condition the MHD solutions can evolve smoothly to a steady-state configuration [Crooker et al, 1998;White et al, 1998;Tanaka, 1999]. However, before the formation of near-Earth neutral line (NENL), a steady state cannot be achieved under the southward IMF condition.…”

Section: Construction Of the Convection Systemmentioning

confidence: 99%

Formation of magnetospheric plasma population regimes coupled with the dynamo process in the convection system

Tanaka

2003

J. Geophys. Res.

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[1] Based on the magnetosphere-ionosphere (M-I) coupling scheme, convection as a compound system is considered including the generation of plasma population regimes in the magnetosphere. In these considerations, primary elements that must be set to a selfconsistent configuration are convection flows in the magnetosphere and the ionosphere, field-aligned current (FAC) systems, ionospheric currents, energy conversion processes, and plasma population regimes. The convection in the M-I coupling system is inextricably associated with the FACs. In the present results, the region-1 and region-2 FACs are driven by rP current inside the magnetosphere through plasma internal energy accumulated in the cusp and plasma sheet, respectively. In this process, mechanisms to drive the region-1 and region-2 FACs are the same two-step process; tangential Maxwell stress on the magnetopause pumps up plasma internal energy inside the magnetosphere, then plasma internal energy drives the FACs. This dynamo can be driven by a steady convection flow which is suitable to project down to the low-b regions. Thus from the magnetohydrodynamic (MHD) force balance controlling the convection, plasma population regimes appear through a requirement to form dynamo in the magnetosphere, showing that plasma population regimes are indispensable to fulfill the self-consistency in the convection system. In the model that the convection is driven directly by the linetying current, the shoulder of the magnetosphere behind the cusp, where the line-tying current is mixed with the pure Chapman-Ferraro current connected to dayside, constructs the dynamo (J.E < 0) for the region-1 FAC. In the present model with negative IMF B z , on the contrary, the Chapman-Ferraro current in this area is not directly connected with the region-1 FAC but connected with the neutral sheet current in the dayside merging region to increase plasma internal energy (J.E > 0) around the cusp. Similarly, tail theta current system acts to increase plasma internal energy in the plasma sheet through the convection. The magnetospheric model derived from this consideration enables a continuous switch over from the confinement state of geomagnetic field in the ChapmanFerraro model to the convection of Dungey model for nonzero IMF B z . In the present convection model, nearly force-free open field lines are extending from the polar cap into the lobes. Based on the convection model proposed in this paper, a suggestion is given for the substorm models in the next decade that they must develop from a modular model to a globally self-consistent model. Citation: Tanaka, T., Formation of magnetospheric plasma population regimes coupled with the dynamo process in the convection system,

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“…The dashed line in the latter insert shows the position of the twisted neutral sheet. These simulations by Tanaka (1999) have revealed the origin of the round cell and the crescent cell in the polar cap and have shown that the merging-cell convection consists of the outer part of the round cell and the crescent cell. Global simulations with a large IMF B y by White et al (1998) have revealed a new feature of the magnetospheric structure: the so-called magnetospheric sash.…”

Section: Global Simulations: Finite B Ymentioning

confidence: 99%

“…There exists still an X line at -20 to -40 R E in the centre of the tail, but lobes with open Figure 6. Ionospheric convection potential in the northern polar cap for a simulation where the IMF was tilted by 45 degrees with respect to the dipole axis (from Tanaka, 1999). magnetic flux also still persist.…”

Section: Global Simulations: Northward Imfmentioning

confidence: 99%

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Space Storms and Space Weather Hazards

Daglis¹

2001

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Subject Terms Report Classification unclassified Classification of this page unclassified Classification of Abstract unclassified Limitation of Abstract UU Number of Pages 486REPORT DOCUMENTATION PAGE Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, -to review recent spacecraft measurements that have provided new insight into the dynamics and effects of space storms; -to review space weather hazards associated with space storms and pertinent to the operation of technological systems in space and on ground;-to discuss and assess methods of space weather forecasting, as well as national and international initiatives towards an efficient development of space climatology.Space weather, the invisible but nevertheless effective result of solar activity and solar-terrestrial coupling, has affected the operations of communication systems since the appearance of telegraph in the 19th century, though as an unknown trouble factor. Nowadays, the effects of space weather affect in various ways all communication modes, from cable to wireless to space-based systems. Moreover, space weather hazards include malfunction or even permanent damage of power distribution grids and of telecommunication, navigation and surveillance satellites, disturbances of over-the-horizon (OTH) radar, HF, VHF and UHF communications, surveying and navigation systems that use Global Positioning System (GPS) satellites, surveillance (optical and radar), and satellite tracking. Space weather influences on the Earth's weather and climate is still a developing topic. Little is known concerning the biological effects of space weather, especially regarding astronauts.This Institute could not be timelier. Space Weather, which has been defined as "conditions on the sun and in the solar wind, magnetosphere, ionosphere, and thermosphere that can influence the performance and reliability of space-and ground-based technological systems and can endanger human life", encompasses a broad range of phenomena impacting both space science and technology. The effects of Space Weather, while present throughout the solar cycle, gain particular prominence around the peak of the 11-year sunspot activity; the maximum of cycle 23 occurred in summer 2000.The fact that this ASI on Space Weather was held in Europe is particularly appropriate. European countries host a considerable repository of knowledge and world-class facilities in this field. Nevertheless, while Space Weather activities in c...

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Configuration of the magnetosphere‐ionosphere convection system under northward IMF conditions with nonzero IMF B_y

Cited by 71 publications

References 16 publications

Interhemispheric observations of dayside convection under northward IMF

Interhemispheric observations of dayside convection under northward IMF

Formation of magnetospheric plasma population regimes coupled with the dynamo process in the convection system

Space Storms and Space Weather Hazards

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