Improving Synchronic Maps with Far-Side Active Region Emergence

Abstract:

Synchronic maps (i.e., maps of the Sun’s photospheric magnetic field over the entire surface at a single instant in time) often serve as the inner boundary condition for global coronal magnetic field and solar wind models. Currently, we use a surface flux transport model to construct synchronic maps every 15 minutes with a resolution of 1024 by 512 in longitude-latitude. This model assimilates magnetic data from SDO/HMI full-disk line-of-sight magnetograms and advects the magnetic field with differential rotation and meridional flow profiles taken directly from the motions of the magnetic elements. Rather than using a diffusivity coefficient, this model explicitly incorporates well-resolved cellular convective flows with spatial and temporal characteristics that match observations, thus retaining the magnetic network structure observed on the Sun.

While this model accurately transports the active regions that are observed on the near-side of the Sun, active regions that emerge on the far-side are neglected until they appear in the observations. Far-side active regions will obviously have a substantial impact on the global coronal field configuration and must be included in useful synchronic maps. We will discuss our attempts to incorporate far-side active region emergence into our flux transport model. We will also illustrate the impact of these improvements.