  The tachocline is believed to be the region where the solar dynamo operates.
With over a solar cycle's worth of data available from the MDI and GONG
instruments, we are in a position to investigate not merely the average
structure of the solar tachocline, but also its time variations. We determine
the properties of the tachocline as a function of time by fitting a
two-dimensional model that takes latitudinal variations of the tachocline
properties into account. We confirm that if we consider central position of the
tachocline, it is prolate. Our results show that the tachocline is thicker at
higher latitudes than the equator, making the overall shape of the tachocline
more complex. Of the tachocline properties examined, the transition of the
rotation rate across the tachocline, and to some extent the position of the
tachocline, show some temporal variations.
