The Sun’s Rotation Near the Interface Between its Convective and Radiative Zones: 1986 to 1990

Abstract

The Sun’s rotation rate near the base of its convection zone might be expected to vary over the solar cycle because of related changes there in the magnetic field. Helioseismic analyses have taught us that much of the Sun’s convection zone rotates with surface-like differential rotation and a transition toward solid body rotation beneath. For a review of what we know about the Sun’s internal rotation, see Goode, et al.(1991). We now have sufficient solar oscillation data to look for changes in the internal rotation near the base of the convection zone. The relevant data are from the 1986, 1988, 1989 and 1990 Big Bear Solar Observatory( BBSO) sets, Libbrecht and Woodard(1992, private communication). These four datasets were gathered at the same site for roughly the same number of days, reduced in the same way and span the same temporal and spatial frequency ranges—the differences between the sets should arise primarily because they were obtained in different years.