Abstract The solar filaments obtained from the daily Ca ii K3 observations at the Coimbra Astronomical Observatory, which is now called the Geophysical and Astronomical Observatory of the University of Coimbra (OGAUC), for the period 1929 – 1941 have been digitized and validated, and they are confirmed to be reliable for solar activity studies. We use these filament data to investigate the rotation and differential degree of the solar high chromosphere. The main results are as follows: (1) the rotation profile of filaments is somewhat steeper than the rotation profile for long-lived Hα filaments; (2) the high chromosphere filaments rotate faster than sunspots, the photosphere, and the medium-low chromosphere at middle-low latitudes; (3) solar filaments rotate at a higher rotation rate in the descending phase of the solar cycle than in the ascending phase, and their rotation velocities are relatively faster around the year of solar maximum. The possible explanation for the above results is given.
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