THREE-DIMENSIONAL MHD SIMULATION OF INTERPLANETARY MAGNETIC FIELD CHANGES AT 1 AU CAUSED BY A SIMULATED SOLAR DISTURBANCE AND A TILTED HELIOSPHERIC CURRENT/PLASMA SHEET |
| |
| Authors: | Wu Chin-Chun Dryer Murray |
| |
| Institution: | (1) Institute of Space Science, National Central University, Chung-Li, Taiwan, ROC;(2) NOAA Space Environment Center, Boulder, CO, 80303, U.S.A. |
| |
| Abstract: | A fully three-dimensional (3D), time-dependent, MHD interplanetary model has been used, for the first time, to study the relationship between one form of solar activity and transient variations of the north–south component, Bz, of the interplanetary magnetic field (IMF) at 1 AU during the active period of a representative solar cycle. Four cases of initial steady-state solar wind conditions, with different tilt angles of the heliospheric current sheet/plasma sheet (HCS/HPS) which is known to be inclined at solar maximum, are used to study the relationship between the location of solar activity and transient variations of the north–south IMF Bz component at 1 AU. We simulated the initialization of the disturbance as a density pulse at different locations near the solar surface for each case of initial steady-state condition and observed the simulated IMF evolution of B (= –Bz) at 1 AU. The results show that, for a given density pulse, the orientation of the corresponding transient variation of Bz has a strong relationship to the location of the density pulse and the initial conditions of the IMF. A recipe for prediction of the initial Bz turning direction is also presented in this study.In previous studies that used this recipe with only a flat HCS/HPS that was coincident with the solar equatorial plane, we found a prediction accuracy of 83% from a data set of 73 events during solar maximum. The present study that incorporates more realistic HCS/HPS tilt angles confirms the earlier work.Our study leads us to suggest that significant Bz values, associated with substantial post-shock temporal periods of hours at 1 AU, could be achieved if large energies (say, 10 32–10 33 erg) were released at the Sun in a flare or helmet de-stabilization process. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
