Research On The Characteristics Of Spatial-temporal Variation Of Sea Level Anomalies And Ocean Currents In The ITF Outflow Region

In this study,the Empirical Orthogonal Function(EOF)are used to analyze the AVISO sea level anomaliesand SODA current data in the outflow region of the Indonesian Throughflow.The results show that there are intraseasonal,semi-annual,annual,interannual and long-term trend variations in the sea level anomalies,while the flow fields are dominated by annual and semi-annual variations.There is significant ascending trend of the sea level anomalies with a value of 0.6 cm/year during 1993 to 2013.The dominant Principal Component(PC1)of the EOF shows interannual variation related to the El Ni?o-Southern Oscillation,with correlation coefficient up to 0.65,suggesting positive/negative sea level anomalies during El Ni?o/La Ni?a events,respectively.The annual cycle of the sea level anomalies is influenced mainly by the South Java Current and the Eastern Gyral Current;and the semi-annual cycle is associated with the eddy that generated by the interaction between the South Java Current and the South Equatorial Current.Analysis also reveals that the sea level anomalies shows distinct intraseasonal variation in the outflow region of the Indonesian Throughflow.The current at the depths of 50 m,100m,200 m,300m,and 500 m in the studyregion show multi-scale variations,which is not only directly affected by the Indonesian Throughflow,but also closely related to the Indian Oceancirculation system,such as the South Equatorial Current,the South Java current and the Leeuwin Current.For the upper layer circulation,the south of Java Island shows the most significant annual variation,while for deeper layer the semi-annual variation becomes dominated.