AN OBSERVATIONAL STUDY OF CORONAL HOLE ROTATION OVER THE SUNSPOT CYCLE

An analysis of the rotation of coronal holes (CHs) spanning 18 years was done based on data from the Catalogue of Coronal Holes (Sanchez-Ibarra and Barraza-Paredes, 1992). A differential rotation of CHs is confirmed for the totality of CHs, but a different behavior was found when those were separated as equatorial or isolated, and polar hole extensions, such as in the Catalogue, Isolated CHs show a typical differential rotation, but polar hole extensions display two different types of behavior: a rotation rate below similar to 40 degrees +/- 5 degrees of heliographic latitude, increasing to the equator, and a rotation rate above the same heliographic latitude but increasing to the poles. Also discussed here is how this last result agrees with other studies that indicate the mostly rigid rotation of the corona at higher latitudes.