Structure of the Indian Ocean Meridional Overturning Circulation and its relationship with the zonal wind stress

We studied the structure of the Indian Ocean (IO) Meridional Overturning Circulation (MOC) by applying a nonlinear inertia theory and analyzed the coupled relationship between zonal wind stress and MOC anomalies. Our results show that the inertia theory can represent the main characteristics of the 10 MOC: the subtropical cell (STC) and cross-equator cell (CEC). The stream function in equatorial and northern TO changes a sign from winter to summer. The anomalies of the zonal wind stress and stream function can be decomposed into summer monsoon mode, winter monsoon mode, and abnormal mode by using the singular vector decomposition (SVD) analysis. The first two modes correlate with the transport through 20 degrees S and equator simultaneously whereas the relationship obscures between the third mode and transports across 20 degrees S and equator, showing the complex air-sea interaction process. The transport experiences multi-time scale variability according to the continuous power spectrum analysis, with major periods in inter-annual and decadal scale.