Solar Physics

, Volume 145, Issue 1, pp 1–10 | Cite as

Rotation rates of small magnetic features from two- and one-dimensional cross-correlation analyses

  • R. W. Komm
  • R. F. Howard
  • J. W. Harvey
Article

Abstract

We present results of an analysis of 628 high-resolution magnetograms taken daily with the NSO Vacuum Telescope on Kitt Peak from 1975 to 1991. Motions in longitude on the solar surface are determined by a two-dimensional cross-correlation analysis of consecutive day pairs. We find that the measured rotation rate of small magnetic features, i.e., excluding active regions, is in excellent agreement with the results of the previous one-dimensional analysis of the same data (Komm, Howard, and Harvey, 1993). The polynomial fits show magnetic torsional oscillations, i.e., a more rigid rotation during cycle maximum and a more differential rotation during cycle minimum, but with smaller amplitudes than the one-dimensional analysis. The full width at half maximum of the cross-correlations is almost constant over latitude which shows that the active regions are effectively excluded. The agreement between the one- and two-dimensional cross-correlation analyses shows that the two different techniques are consistent and that the large-scale motions can be divided into rotational and meridional components that are not affected by each other.

Keywords

Active Region Rotation Rate Solar Surface Differential Rotation Rigid Rotation 

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References

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Copyright information

© Kluwer Academic Publishers 1993

Authors and Affiliations

  • R. W. Komm
    • 1
  • R. F. Howard
    • 1
  • J. W. Harvey
    • 1
  1. 1.National Solar ObservatoryNational Optical Astronomy ObservatoriesTucsonUSA

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