Rotation of Doppler features in the solar photosphere

Abstract

The pattern rotation rate for the line-of-sight velocity features in the solar photosphere is determined by cross-correlating Doppler residual coarse arrays from magnetograph observations. From the latitude dependence and the approximately one-day lifetime of the correlation amplitudes, it is concluded that the dominant velocity pattern producing the correlation is the supergranulation network. The rotation rate average over the entire period is determined. The rate at all latitudes is about 2 percent faster than the magnetic and sunspot rates and about 4 percent faster than the Mount Wilson spectroscopic rate. Comparing this coarse array determination with Duvall's (1988) earlier result indicates that the supergranulation pattern may be a very sensitive indicator of large-scale motions at the top of the solar convection zone.