Relating Agulhas leakage to the Agulhas Current retroflection location

[摘要] The relation between the Agulhas Current retroflection location and themagnitude of Agulhas leakage, the transport of water from the Indian to theAtlantic Ocean, is investigated in a high-resolution numerical ocean model.Sudden eastward retreats of the Agulhas Current retroflection loop arelinearly related to the shedding of Agulhas rings, where larger retreatsgenerate larger rings. Using numerical Lagrangian floats a 37 year timeseries of the magnitude of Agulhas leakage in the model is constructed. Thetime series exhibits large amounts of variability, both on weekly and annualtime scales. A linear relation is found between the magnitude of Agulhasleakage and the location of the Agulhas Current retroflection, both binned tothree month averages. In the relation, a more westward location of theAgulhas Current retroflection corresponds to an increased transport from theIndian Ocean to the Atlantic Ocean. When this relation is used in a linearregression and applied to almost 20 years of altimetry data, it yields a bestestimate of the mean magnitude of Agulhas leakage of 13.2 Sv. The earlyretroflection of 2000, when Agulhas leakage was probably halved, can beidentified using the regression.

[学科分类] 海洋学与技术