HR: 1330h
AN: SH13A-09    [Abstracts]
TI: Source Surface Models and Their Impact on Solar Wind Research
AU: * Sokolov, I V
EM: igorsok@umich.edu
AF: CSEM, Department of AOSS,University of Michigan , 2455 Hayward Street, Ann Arbor, MI 48109-2143 United States
AU: Roussev, I I
EM: iroussev@umich.edu
AF: CSEM, Department of AOSS,University of Michigan , 2455 Hayward Street, Ann Arbor, MI 48109-2143 United States
AU: Gombosi, T I
EM: tamas@umich.edu
AF: CSEM, Department of AOSS,University of Michigan , 2455 Hayward Street, Ann Arbor, MI 48109-2143 United States
AU: Liu, Y
EM: yliu@quake.stanford.edu
AF: W. W. Hansen Experimental Physics Laboratory , Stanford University, Stanford, CA United States
AB: To perform realistic modeling of the important processes in the solar corona, such as coronal mass ejections, flares, as well as the acceleration of solar particles, one needs to incorporate into the physical models any complicated pattern of the coronal magnetic field. The coronal magnetic field topology is determined by the helmet streamers (with closed field lines), the coronal holes (with open field lines) as well as the fine, but crucially important, details of the small-scale active regions. The standard practice to recover the global 3-D structure of the solar magnetic field from observations is to use the source surface model, in which the field is assumed to be potential, i.e., current-free. This approach ignores any volumetric current there may be present in the corona, and also neglects the existence of the equatorial current sheet, which starts from a height of 3-5 Rs above the solar surface. The fully potential solar magnetic field would have only closed field lines, not allowing for the solar wind to exist. In our Solar Corona model, incorparated into the Space Weather Modelling Framework, the solar magnetic field is split into two constituitive parts: one potential part which is recovered from the magnetic field data (e.g., from WSO, MWO, or MDI data) using the source surface method; and, one other non-potential part. For the potential field, we keep only the spherical harmonics decreasing with distance from the Sun or, equivalently, we use a very large value of the source surface radius. For the non-potential field, we solve the time-dependent induction equation with zero boundary condition at the solar surface. The full set of conservation laws for the MHD system is solved numerically using the BATS-R-US code. To power the solar wind in our model, we use a phenomenological turbulence model described in an earlier paper. The resulting steady-state MHD solution includes the well-resolved current sheet and helmet streamers. The modeled structure of active regions is very close to that recovered from the same magnetic data by assuming the potential magnetic field with a smaller source surface radius (2.5 Rs). The important difference, however, is in theappearance of a strong current loop near the active region being studied,namely AR 10486 on Oct 27, 2003.
DE: 2134 Interplanetary magnetic fields
DE: 7509 Corona
DE: 7524 Magnetic fields
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2005 Joint Assembly