HR: 13:50h
AN: SH23C-02 INVITED     [Abstracts]
TI: How Good are Potential Field Source Surface Models? What the MHD Modelers Don't Want you to Know
AU: * Riley, P
EM: pete.riley@saic.com
AF: Science Applications International Corporation, 10260 Campus Point Dr., San Diego, CA 92124 United States
AU: Linker, J A
EM: linkerj@saic.com
AF: Science Applications International Corporation, 10260 Campus Point Dr., San Diego, CA 92124 United States
AU: Mikic, Z
EM: mikicz@saic.com
AF: Science Applications International Corporation, 10260 Campus Point Dr., San Diego, CA 92124 United States
AU: Lionello, R
EM: lionel@iMHD.net
AF: Science Applications International Corporation, 10260 Campus Point Dr., San Diego, CA 92124 United States
AU: Ledvina, S
EM: ledvina@ssl.berkeley.edu
AF: University of California, Berkeley, Space Sciences Lab, 7 Gauss Way, Berkeley, CA 94720-7450 United States
AB: The large-scale, steady-state magnetic field configuration of the solar corona is typically computed using boundary conditions derived from photospheric observations. The two most popular approaches in use today are: (1) potential field, source surface (PFSS) models; and (2) magnetohydrodynamic (MHD) models. The former have the advantage that they are: simple to develop and implement; require relatively modest computer resources; and can resolve global structure on spatial scales beyond those that can be handled by current MHD models. On the other hand, they have been criticized because their basic assumptions (that the field is potential and that a single, spherical source surface exists) are seldom, if ever, met. In addition, PFSS models cannot directly incorporate time dependent phenomena, such as magnetic reconnection. In this study, we assess how well PFSS models can reproduce the large-scale quasi-static magnetic structure of the corona by making detailed comparisons with MHD solutions at different phases in the solar activity cycle. Specifically, we: (1) compute the shape of the source surface as inferred from the MHD solutions; (2) compare the coronal hole boundaries as determined using the two models; and (3) correlate the open flux determined from the models with the magnetic flux observed at 1 AU. Our results suggest that PFSS models compare relatively well with MHD computations of untwisted coronal fields (matched to line-of-sight magnetograms). It remains an open question how well PFSS models compare with MHD models that match vector magnetograms. This question can be addressed once data from SOLIS and Solar-B are incorporated into the MHD models.
DE: 7509 Corona
DE: 7524 Magnetic fields
DE: 7536 Solar activity cycle (2162)
DE: 7827 Kinetic and MHD theory
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2005 Joint Assembly