Magnetosphere (Global): Database Site

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		Interaction between the solar wind and earth's magnetosphere
		FIGURE
		MOVIE
		VRML

From the sun, the wind of plasma, namely "solar wind" is always radiated with light and electromagnetic waves in the space of solar system. The solar wind highly changes by explosion phenomena such as solar flare on the solar surface and it develops by interaction between slow and fast solar winds to form interplanetary shocks while it propagates from the sun to the earth. The interplanetary disturbances cause the action with collision to the earth's magnetosphere. Typical parameters of the solar wind in the earth vicinity are the number density 5 /cc, velocity 400 km/s, temperature 10000 K, interplanetary magnetic field 5 nT. The number density and magnetic field strength become over 10 times when interplanetary disturbances greatly develop.

Relationship between sun and earth (Prof. Y. Kamide and NGDC/NOAA)

The earth has the intrinsic magnetic field and it has the role of first shielding wall which prevents the invasion of high energy charged particles from the sun and solar wind. The intrinsic magnetic field is impinged by the pressure of solar wind and the magnetosphere has a rounded shape in the sun side, on the contrary it becomes a shape of the long tail in the anti-sun side, which is extended long along the flow direction of solar wind like the streamer. It is the region where the achievement range of the intrinsic magnetic field is called as magnetosphere. The earth's magnetosphere is a shape like streamer, and the size of sun side from earth center is about 10 Re and tail part is 100-1000 Re, and the radius is about 20-30 Re, where Re means earth radius (6370 km).

Earth's magnetosphere (NIPR)

Though the intrinsic magnetic field was explained to have generally the role of first shielding wall which prevents direct invasion of solar wind, it frequently breeds from solar wind, and the window can open by relationship between leaving interplanetary magnetic field (IMF) and geomagnetic field in the wall, then plasma and energy of solar wind partially penetrates into the magnetosphere. It is magnetic reconnection to fulfill the main role for the switching of the window. When the IMF is southward, magnetic reconnection occurs in the front of the magnetosphere (subsolar point) and a large amount of energy is carried into the magnetosphere to be accumulated in the tail. If the limit which the tail can stably accumulate is exceeded, the energy will be suddenly emitted in the ionosphere side and the tail side. At the ionosphere side, it becomes explosive increase luminosity of aurora and also becomes plasmoid ejection which is a hot lump of plasma confined by the magnetic island by the tail side.

Noon-midnight meridian plane and cross sectional plots of the earth's magnetosphere as the interplanetary magnetic field (IMF) is the south direction. The strength of magnetic field (B) and plasma temperature (T) are displayed by a color code, and the magnetic field and velocity are expressed as vector. The plasma sheet of a tail part is very thin and magnetic field lines become a shape of tail extended in the x-direction.

Equatorial plane and cross sectional plots of the earth's magnetosphere as the IMF is south direction. The strength of magnetic field (B) and plasma temperature (T) are displayed by a color code, and the magnetic field and velocity are expressed as vector. The cross section in the tail is elongated in north-south direction and the temperature is high in the plasma sheet.

Three-dimensional magnetic field structure of the earth's magnetosphere as the interplanetary magnetic field (IMF) is the south direction. Magnetic field lines become a shape of tail extended in the x-direction. The magnetic reconnection occurs in boundary of dayside magnetopause and tail. The closed magnetic field lines are displayed by green, open lines by blue, and lines away from the earth by red.

Two dimensional distributions of velocity projected on polar region, energy flux, potential, field aligned currents as the IMF is the south direction. Plus and minus are displayed by red and blue, open-closed boundary are displayed by green line. Two cell convection pattern appears, and open-closed boundary of magnetic field lines agrees with reversal region of the polar region convection.

When the IMF is northward, magnetic reconnection occurs in the high latitude tail region (rear in the cusp) and the reconnection rate becomes smaller than that for southward IMF. Therefore geomagnetic pulsations and aurora activity become relatively quiet. However, it is known that peculiar theta aurora appears along the sun-earth line. Also, though it has been considered that the energy storage in the magnetosphere could be small due to small geomagnetic pulsation and low activity of aurora for northward IMF, it also comes from the facts that observations on the electric current flow and particle precipitation from magnetosphere to ionosphere have been done mainly in the ionosphere. That is, the total energy amount stored in the magnetosphere does not always well known from the observation.

Noon-midnight meridian plane and cross sectional plots of the earth's magnetosphere as the IMF is the north direction. The strength of magnetic field (B) and plasma temperature (T) are displayed by a color code, and the magnetic field and velocity are expressed as vector. The plasma sheet of a tail part is very thick and magnetic field lines become round shape.	Equatorial plane and cross sectional plots of the earth's magnetosphere as the IMF is north direction. The strength of magnetic field (B) and plasma temperature (T) are displayed by a color code, and the magnetic field and velocity are expressed as vector. The cross section in the tail is elongated in morning-evening direction and the temperature is low in the plasma sheet.
Three-dimensional magnetic field structure of the earth's magnetosphere as the IMF is the north direction. Tail part of magnetic field lines become round shape. The magnetic reconnection occurs in the high latitude tail region (rear in the cusp). Since the reconnection in the high latitude tail region occurs simultaneously in south-north symmetry, a closed magnetosphere is formed.	Two dimension distributions of velocity projected on polar region, energy flux, potential, field aligned currents as the IMF is the north direction. Four cell convection pattern appears, and open-closed boundary of magnetic field lines became small and disappeared, and a closed field configuration is formed.

Like this, it is the research of solar wind-magnetosphere interaction to examine how and how much the plasma and energy flow into the magnetosphere, and are stored and suddenly released/consumed depending the solar wind and IMF conditions. Where and what kinds of energy are accumulated and what mechanisms does work to the sudden energy release processes. As an actual problem, the sun and hence solar wind and IMF continuously fluctuate and response of the magnetosphere consequently changes. Thus the actuality is very complicated like this. Therefore, in the study of solar wind-magnetosphere interaction, the method for examing individual response of magnetosphere in proportion to the change of IMF and solar wind as an element has been adopted first of all. It has been used as part of space weather study that 3D global MHD simulation of the solar wind-magnetosphere interaction to use the solar wind and IMF parameters from satellite observations as input was also started in the international cooperation program.

Space Weather Sutdy

Location of satellite for Space Weather Sutdy

*please click to look at enlarged figures

Three-dimensional magnetic field structure of the earth's magnetosphere as the IMF is the south direction. Magnetic field lines become shape of tail extended in the x-direction. The magnetic reconnection occurs in boundary of dayside magnetopause and tail. The closed magnetic field lines are displayed by green, open lines by blue, and lines away from the earth by red.	Three-dimensional magnetic field structure of the earth's magnetosphere as the IMF is the north direction. Tail part of magnetic field lines become round shape. The magnetic reconnection occurs in the high latitude tail region (rear in the cusp). Since the reconnection in the high latitude tail region occurs simultaneously in south-north symmetry, closed magnetosphere is formed.
Noon-midnight meridian plane and cross sectional plots of the earth's magnetosphere as the IMF is the south direction and the tilt of dipole magnetic axis is 30 degrees. The strength of magnetic field (B) and plasma temperature (T) are displayed by a color code, and the magnetic field and velocity are expressed as vector. Since magnetic axis tilts, the north-south asymmetry occurs, and the neutral sheet located on the magnetic equator in the earth vicinity, and it rises in the meridian plane which connects the sun with the earth, it would be paralleled for the direction of flow of solar wind in the tail. In the tail part the plasma sheet is thin, magnetic field lines form antiparallel structure, and the magnetic reconnection occurs. And, the neutral sheet is warped in the tail cross section.	Noon-midnight meridian plane and cross sectional plots of the earth's magnetosphere as the IMF is the north direction and the tilt of dipole magnetic axis is 30 degrees. The strength of magnetic field (B) and plasma temperature (T) are displayed by a color code, and the magnetic field and velocity are expressed as vector. Since magnetic axis tilts, the north-south asymmetry occurs, and in the tail part plasma sheet and magnetic field lines become round shape, and the neutral sheet is thick. In the summer hemisphere, the place where reconnection occurs in the high latitude tail region moves in the sun direction, and in the winter hemisphere, it moves in the tail direction.
Three-dimensional magnetic field structure of the earth's magnetosphere as the IMF is the south direction and the tilt of dipole magnetic axis is 30 degrees. The neutral sheet located on the magnetic equator in the earth vicinity, and it rises in the meridian plane which connects the sun with the earth, it would be paralleled along the flow direction of the solar wind in the tail. There is a bending point of the neutral sheet. Since there is the flow in the region where reconnection occurs on origin, the reconnection rate in near dayside magnetosphere and magnetic equator decreases in comparison with the case in which there is no inclination of the magnetic axis.	Three-dimensional magnetic field structure of the earth's magnetosphere as the IMF is the south direction and the tilt of dipole magnetic axis is 30 degrees. In the tail, it is difficult that the neutral sheet is clarified by doing the shape of magnetic field lines is round. Since magnetic axis tilts, the north-south asymmetry occurs, and in the summer hemisphere, the place where reconnection occurs in the high latitude tail region moves in the sun direction, and in the winter hemisphere, it moves in the tail direction. When there is a inclination in the magnetic axis, open magnetic field lines ( blue ) in which IMF even in the due north direction is formed, and closed magnetosphere is not formed.
Three-dimensional magnetic field structure of the earth's magnetosphere and the distribution of flow and plasma temperature, as the IMF is in the north and dusk direction and the tilt of dipole magnetic axis is 30 degrees. The three-dimensional image described using the VRML, it is viewed from the dusk direction in the parallel projection. Due to inclination of the magnetic axis and the duskward IMF ( By component ) symmetry is not established. The closed magnetic field lines are displayed by green, open lines are displayed by blue. In the northern hemisphere, magnetic reconnection region moves in sun direction and evening direction, and in the southern hemisphere, it moves in tail direction and morning direction.	Three-dimensional magnetic field structure of the earth's magnetosphere and the distribution of flow and plasma temperature, as the IMF is in the north and evening direction and the tilt of dipole magnetic axis is 30 degrees. The three-dimensional image described using the VRML, it is viewed from the sun and north evening direction in the perspective. The plasma temperature is displayed volume rendering. The magnetic reconnection occurs in the northern hemisphere evening side firstly, and blue magnetic field lines of the reconnection covers the magnetopause in the southern hemisphere morning side, and it flows in the tail direction, and reconnection occurs in the tail again.
Three-dimensional magnetic field structure of the earth's magnetosphere and the distribution of flow and plasma temperature, as the IMF is in the south and evening direction and the tilt of dipole magnetic axis is 30 degrees. The three-dimensional image described using the VRML, it is viewed from the evening direction in the parallel projection. Due to inclination of the magnetic axis and dusk direction IMF (By component ), symmetry is not established.	Three-dimensional magnetic field structure of the earth's magnetosphere and the distribution of flow and plasma temperature, as the IMF is in the south and evening direction and the tilt of dipole magnetic axis is 30 degrees. The three-dimensional image described using the VRML, it is viewed from the sun and north evening direction in the perspective. Magnetic reconnection, since it is generated in anti-parallel magnetic field region in the magnetic equator vicinity, magnetic field lines of reconnection which is extended in the north morning direction has severely bent, and the bending loosely increases on magnetic field lines of reconnection which is extended in the south evening direction in the tail direction.

Animation movie of the result of solar wind and three-dimensional global magnetohydrodynamic (MHD) simulation of the interaction of the solar wind with the earth's magnetosphere ( gif format ).

Three-dimensional visualization image file which made solar wind and data of the three-dimensional global MHD simulation of interaction of the solar wind with the earth's magnetosphere using VRML(Virtual Reality Modeling Language). It is possible to observe using VRML Viewer such as CosmoPlayer.

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