  Using data from the Michelson Doppler Imager (MDI) instrument on board the
Solar and Heliospheric Observatory (SOHO), we study the large-scale velocity
fields in the outer part of the solar convection zone using the ring diagram
technique. We use observations from four different times to study possible
temporal variations in flow velocity. We find definite changes in both the
zonal and meridional components of the flows. The amplitude of the zonal flow
appears to increase with solar activity and the flow pattern also shifts
towards lower latitude with time.
