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pure and applied geophysics

, Volume 63, Issue 1, pp 196–204 | Cite as

The longitudinal proper motion of sunspots and the solar rotation rate

  • Fred Ward
Article

Summary

The longitudinal proper motion of sunspot groups has been shown to be a function of their size and relative extension in longitude. Two theories are proposed to explain these effects, which theories assume that the wind circulation of the spots and the wind field surrounding the spots are intimately connected, and dynamically interact. The retardation in the motion of large spot groups is hypothesized to be due to the effect of the latitudinal variation of the Coriolis parameter (on a rotating spherical body) and an assumed vortical circulation around the spots. The more rapid longitudinal motion of extended spot groups is suggested to be the result of the preferential occurrence and development of such groups in regions of above-average horizontal wind and wind shear. If these theories are essentially correct, the real solar rotation rate—i.e., the longitude- and time-averaged fluid motion field—should be derived from the motions of small spot groups, and is 1% to 11/2% higher than the usually accepted rate whichNewton andNunn derived.

Keywords

Wind Field Wind Shear Fluid Motion Horizontal Wind Sunspot Group 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Birkhäuser Verlag 1966

Authors and Affiliations

  • Fred Ward
    • 1
  1. 1.Air Force Cambridge Research LaboratoriesBedfordUSA

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