The interaction of a magnetic cloud with the Earth: Ionospheric convection in the northern and southern hemispheres for a wide range of quasi-steady interplanetary magnetic field conditions

1993 ◽  
Vol 98 (A5) ◽  
pp. 7633-7655 ◽  
Author(s):  
M. P. Freeman ◽  
C. J. Farrugia ◽  
L. F. Burlaga ◽  
M. R. Hairston ◽  
M. E. Greenspan ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Magnetic Cloud ◽  
Field Conditions ◽  
Ionospheric Convection ◽  
The Earth ◽  
Wide Range ◽  
Northern And Southern Hemispheres

scholarly journals Ionospheric convection during nonsteady interplanetary magnetic field conditions

1997 ◽  
Vol 102 (A7) ◽  
pp. 14563-14579 ◽  
Author(s):  
A. J. Ridley ◽  
Gang Lu ◽  
C. R. Clauer ◽  
V. O. Papitashvili
Keyword(s):  
Magnetic Field ◽  
Interplanetary Magnetic Field ◽  
Field Conditions ◽  
Ionospheric Convection

scholarly journals Cellular automata model of magnetospheric-ionospheric coupling

2003 ◽  
Vol 21 (9) ◽  
pp. 1931-1938 ◽  
Author(s):  
B. V. Kozelov ◽  
T. V. Kozelova
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Cellular Automata ◽  
Interplanetary Magnetic Field ◽  
Control Parameter ◽  
Energy Content ◽  
Nonlinear Phenomena ◽  
Cellular Automata Model ◽  
The Earth ◽  
Magnetospheric Tail

Abstract. We propose a cellular automata model (CAM) to describe the substorm activity of the magnetospheric-ionospheric system. The state of each cell in the model is described by two numbers that correspond to the energy content in a region of the current sheet in the magnetospheric tail and to the conductivity of the ionospheric domain that is magnetically connected with this region. The driving force of the system is supposed to be provided by the solar wind that is convected along the two boundaries of the system. The energy flux inside is ensured by the penetration of the energy from the solar wind into the array of cells (magnetospheric tail) with a finite velocity. The third boundary (near to the Earth) is closed and the fourth boundary is opened, thereby modeling the flux far away from the tail. The energy dissipation in the system is quite similar to other CAM models, when the energy in a particular cell exceeds some pre-defined threshold, and the part of the energy excess is redistributed between the neighbouring cells. The second number attributed to each cell mimics ionospheric conductivity that can allow for a part of the energy to be shed on field-aligned currents. The feedback between "ionosphere" and "magnetospheric tail" is provided by the change in a part of the energy, which is redistributed in the tail when the threshold is surpassed. The control parameter of the model is the z-component of the interplanetary magnetic field (Bz IMF), "frozen" into the solar wind. To study the internal dynamics of the system at the beginning, this control parameter is taken to be constant. The dynamics of the system undergoes several bifurcations, when the constant varies from - 0.6 to - 6.0. The Bz IMF input results in the periodic transients (activation regions) and the inter-transient period decreases with the decrease of Bz. At the same time the onset of activations in the array shifts towards the "Earth". When the modulus of the Bz IMF exceeds some threshold value, the transition takes place from periodic to chaotic dynamics. In the second part of the work we have chosen as the source the real values of the z-component of the interplanetary magnetic field taken from satellite observations. We have shown that in this case the statistical properties of the transients reproduce the characteristic features observed by Lui et al. (2000).Key words. Magnetospheric physics (magnetosphere-ionosphere interactions) – Space plasma physics (nonlinear phenomena)

scholarly journals The Earth's passage of the April 11, 1997 coronal ejecta: geomagnetic field fluctuations at high and low latitude during northward interplanetary magnetic field conditions

1999 ◽  
Vol 17 (10) ◽  
pp. 1245-1250 ◽  
Author(s):  
S. Lepidi ◽  
P. Francia ◽  
U. Villante ◽  
A. Meloni ◽  
A. J. Lazarus ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Interplanetary Magnetic Field ◽  
Geomagnetic Field ◽  
Field Conditions ◽  
Mhd Waves ◽  
Low Latitude ◽  
Terra Nova Bay ◽  
Field Fluctuations ◽  
Terra Nova

Abstract. An analysis of the low frequency geomagnetic field fluctuations at an Antarctic (Terra Nova Bay) and a low latitude (L'Aquila, Italy) station during the Earth's passage of a coronal ejecta on April 11, 1997 shows that major solar wind pressure variations were followed at both stations by a high fluctuation level. During northward interplanetary magnetic field conditions and when Terra Nova Bay is close to the local geomagnetic noon, coherent fluctuations, at the same frequency (3.6 mHz) and with polarization characteristics indicating an antisunward propagation, were observed simultaneously at the two stations. An analysis of simultaneous measurements from geosynchronous satellites shows evidence for pulsations at approximately the same frequencies also in the magnetospheric field. The observed waves might then be interpreted as oscillation modes, triggered by an external stimulation, extending to a major portion of the Earth's magnetosphere. Key words. Magnetospheric physics (MHD waves and instabilities; solar wind-magnetosphere interactions)

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