The large scale tropical circulation, commonly named the Hadley circulation, is a key element in the global heat and moisture transport. Traditionally it is defined as the meridional circulation of the zonally averaged flow in the tropics, but in recent years studies have shown the importance of looking at the decomposition of the three-dimensional atmospheric flow into local meridional and zonal circulations. These studies gave useful analysis on the regionality and variability of the meridional circulation in different time scales, but were mostly limited to examining the regional strengthening/weakening of the circulation. Here we study the interannual variability of the longitudinally-dependent meridional circulation (LMC), with a focus on its zonal shift. We use hierarchical clustering to objectively determine the 5 main modes of the LMC interannual variability, and apply a Lagrangian air parcel tracking method to reveal the detailed patterns of the circulation. We find that the most prominent interannual variability of the LMC is an east-west shift, which plays a dominant role in the overall interannual variability of the tropical circulation. In addition, the LMC variability is found to be strongly related to other atmospheric variables such as the sea surface temperature, precipitation and air temperature. Using multiple linear regression we analyze these dependencies and discuss their implications for the tropical climate system. We also relate the LMC interannual variability to the Madden-Julian Oscillation (MJO) and find that the 2 La-Nina related modes are significantly correlated with 2 different MJO phases.