We thank Fei-Fei Jin and an anonymous reviewer for their useful comments. Use of freely available data from the TAO/TRITON array (http://www.pmel.noaa.gov/tao/) and from the Ocean Surface Currents Analyses–Real time (OSCAR) dataset (http://www.oscar.noaa.gov/index.html) is gratefully acknowledged. All MSSA and SSA were performed with the SSA-MTM tool kit, which was obtained from http://www.atmos.ucla.edu/tcd/ssa/. We are very grateful to Rong-Hua Zhang for providing the latest version of the ICM. This work was supported by the European projects ENSEMBLES (GOCE-CT-2003-505539) and DYNAMITE (Contract 003903).
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