Data from the series of HAO K-coronameters located at Mauna Loa, Hawaii, are analyzed with an autocorrelation technique for the purpose of defining the variation of synodic rotation period and white-light structure persistence as a function of the solar activity cycle. The time-averaged results yield a rotation law of ω = 14.21-0.57 sin²φ degrees per day, where ω is the sidereal rotation rate at latitude φ. This is equal to the sunspot rotation rate at the equator but is much more rigid than rotational characteristics of photospheric magnetic fields or sunspots. A variation of the rotation rate is observed, with a definite dependence upon the level of solar activity.
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Fisher et al. (1984) studied this question.