A study of temporal variations of the tachocline

Abstract

Temporal variations of the structure and rotation rate in the solar tachocline region are studied using helioseismic data from the Global Oscillation Network Group (GONG) and the Michelson Doppler Imager (MDI) obtained during the period 1995-2000. We do not find any significant temporal variation in the depth of the convection zone, the position or thickness of the tachocline or the extent of overshoot below the convection zone. We find evidence to suggest that the mean position of tachocline becomes shallower with increase in latitude, strengthening earlier results. The convection zone depth is found to be essentially independent of latitude.