PFSS

Potential Field Source Surface Models provide an approximate description of the solar coronal magnetic field based on observed photospheric fields (magnetograms). They were initially developed by Altschuler and Newkirk (Sol. Phys. 9, 131, 1969) and Schatten et al. (Sol. Phys. 6, 442, 1969), and later refined by Hoeksema (1984 Thesis, Stanford University) and Wang and Sheeley (ApJ 392, 310, 1992).

The Potential Field Surface Model calculates the magnetic field of the solar corona using observations of the magnetic field at the sun's surface. This code was written by Janet Luhmann. The model calculates the magnetic field of the corona from the radius of the sun to the source surface radius assuming that there are no currents in this region. The magnetic field in this case satisfies curl B = 0. The source surface radius is the outer boundary and is set by the user. The range of acceptable values is 1.6 - 3.25 solar radii with 2.5 the recommended value.

The code uses spherical harmonic coefficients calculated by Wilcox Solar Observatory using observed photospheric fields (magnetograms) as input. The inner boundary condition assumes that the magnetic field of the sun is nearly radial. At the source surface radius, the magnetic field is assumed to be radial.

Spherical harmonic coefficients for specific date or Carrington rotation and source surface radius.

Magnetic field of the sun from one solar radius to the source surface radius.