Magnetic Fields at Mt. Wilson and MDI

Magnetic Fields atMt. Wilson and MDI

The 150-foot Tower Spectrograph Measures 12 line pairs simultaneously

• The long-term program uses 5250.

• The full coverage of 6768 allows modeling of MDI.

• The Na D2 line permits interesting studies of height dependence.

The Fluxtube Magnetic Structure Complicates Interpretation

• This diagram shows the relationship between the magnetic structure and our points of observation.

Comparison between MWO and MDI

• We interpolate and bin the MDI magnetogram to match the temporal/spatial location of MWO pixels. This is MWO as seen by MDI.

• We reconstruct the 6768 line profile and apply model MDI filters to it to find a MWO-modeled field. This is MDI as seen by MWO.

Temporal trends near disk center

• Approximately 1200 MWO/MDI intercomparisons have been constructed to yield a scale factor between MDI and MWO.

• These two are for near disk center areas.

Temporal trends near the limb.

• The outer sections of the solar image have been divided into quadrants. The scatter is much larger here and there are fewer points per image.

Magnetic geometries are not all vertical.

• The potential field solutions used in the Wang-Sheeley model assume the field geometry is vertical at the photosphere. This is demonstrably an inaccurate assumption.

The geometry of the rotating sun and magnetic fields

Solar rotation and magnetic geometry.

Neutral lines and tilt map

Comparison to TRACE