HR: 1340h
AN: SH53A-1072    [Abstracts]
TI: An MHD simulation model of the global solar corona with the time-varying boundary magnetic field driven with the current at the lower corona
AU: * Hayashi, K
EM: keiji@quake.stanford.edu
AF: Stanford University, W.W.Hansen Experimental Phys. Lab., 491 South Service Road Cypress, Stanford, CA 94305-4085, United States
AB: A time-dependent three-dimensional MHD simulation model to treat the response of the solar corona to the temporal variations of the global solar photospheric magnetic field is proposed. In order to avoid the computational difficulties in calculating the vector quantities of the magnetic field and plasma motion on the boundary surface fully matching the measured variations, we assumed the shallow spherical layer at the lowermost corona for which the "differential potential field" is calculated and superimposed to the existing corona. The differential potential field uses differential synoptic map that is calculated by subtracting two successive synoptic maps of the solar photospheric magnetic field measurement data. The radial component of the differential field at the upper sphere set at 1.1 Rs sphere is zero. The differential potential field confined in a shallow spherical layer can be regarded as the proxy of the global variation of the coronal magnetic field during one Carrington rotation period of about 27 days. By gradually adding the differential potential field to the existing numerical coronal magnetic field, we can simulate the continuous coronal variations in the global scale. The potential field is calculated by the spherical harmonics up to 5th term, which corresponds to about 10-degree spatial resolution to treat only the global scale and to neglect the small-scale quick surface variations. This model assumes the strong current at the upper sphere of the shallow spherical layer that we here chose at 1.1 Rs, which may not represent the real corona. It is, however, beneficial to examine a lot of new features numerically obtained, such as the twisted magnetic loops and the mass condensations along the magnetically neutral lines, and the magnetic reconfigurations at the streamer.
DE: 7509 Corona
DE: 7524 Magnetic fields
DE: 7833 Mathematical and numerical techniques (0500, 3200)
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2007 Fall Meeting