Calculations of the Solar Internal Angular Velocity for 1986--1990

Frequency splitting data obtained at the Big Bear Solar Observatory for the years 1986, 1988, 1989, and 1990 are analyzed by a modified forward calculation in order to find the simplest solutions which embody the essential features of those data. The solutions are used to identify the properties of the Sun's internal angular velocity that are common to all years and to study possible changes from year to year. The common properties include a maximum in the angular velocity at all latitudes just below the surface and a shear zone (negative outward), at high latitudes near the base of the convection zone. Surprisingly, there is no indication of a shear zone at intermediate latitudes, and at low latitudes there is only a weak suggestion of a shear in 1989 and 1990. While there is some evidence of other changes in the internal angular velocity from year to year, they do not appear to be qualitatively significant.