Differential rotation of chromosphere and photosphere in the rising phase of N22 cycle of the Sun: torsional oscillations

Abstract

The angular velocities of chromosphere and photosphere are calculated for 1987–1990 on the basis of heliographic coordinates of the chromospheric flares and sunspots (Solar Geophysical Data). The time resolution accepted is 0.25 year. The mean equatorial rotations of chromosphere and photosphere practically coincide. However, the differential coefficients in the chromosphere and photosphere, b, have strongly different behaviour. The value bch – bph change regularly from “+” sign to “−” sign over two-year interval. Thus, the idea of a torsion like oscillations of “chromosphere–photosphere” is supported.