Dipolarization of the earth magnetic field and charge particles precipitation from the magnetic flux tube
During the expansion phase of the substorm in the nightside magnetosphere enhancement of the magnetic field and decrease the plasma pressure is observed simultaneously. Enhancement of the magnetic field is recorded at first in the tail of the magnetosphere, and then at more closer distances from the Earth. This process takes a few minutes and covers the region in the magnetosphere of 10 Earth radii. One of possible explanations of this phenomenon is associated with cooling magnetic flux tubes caused by the precipitation of the energetic particles in the ionosphere. We have made evaluation of the effectiveness of this mechanism.
1. Runov A., Angelopoulos V., Sitnov M. I. et al. THEMIS observations of an earthward-propagating dipolarization front // Geophysical Research Letters. 2009. Vol. 36.
2. Birn J., Raeder J., Wang Y. L. et al. On the propagation of bubbles in the geomagnetic tail // Ann. Geophys. 2004. №22. P. 1773—1786.
3. Volkov M. A., Namgaladze A.A Models of field-aligned currents needful to simulate the substorm variations of the electric field and other parameters observed by EISCAT // Annales Geophysicae. 1996. Vol. 14, № 12. P. 1356—1361.
4. Knight S. Parallel electric fields // Planet. Space Sci. 1973. №21.
5. Vaivads A. et al. What high altitude observations tell us about the auroral acceleration: A Cluster/DMSP conjunction // Geophysical Research Letters. 2002. Vol. 30.Iss. 3. P. 6—1.
6. Tsyganenko N. A. Modeling the Earth's Magnetospheric Magnetic Field Confined Within a Realistic Magnetopause // J. Geophys. Res. 1995. №100. P. 5599—5612.
7. Liou K., Meng C.-I., Lui A. T. Y. et al. Magnetic dipolarization with substorm expansion onset // J. Geophys. Res. 2002. 107(A7).
8. Marklund G., Sandahl I., Opgenoorth H. A study of the dynamics of a discrete auroral arc // Planet. Space. Sci. 1982. Vol. 30. P. 179.