A study of possible temporal and latitudinal variations in the properties of the solar tachocline

Abstract

Temporal variations of the structure and the rotation rate of 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 of the tachocline or the extent of overshoot below the convection zone. No systematic variation in any other properties of the tachocline, like width, etc., is found either. Possibility of periodic variations in these properties is also investigated. Time-averaged results show that the tachocline is prolate with a variation by about 0.02R_sun in its position. The depth of the convection zone or the extent of overshoot does not show any significant variation with latitude.Comment: To appear in MNRA