Time-frequency variability of Kuroshio meanders in Tokara Strait

Abstract

The meander of the Kuroshio path, with periods of 30-90 days, dominates Tokara Strait, Japan. To understand the time-frequency variability of this meander, two Kuroshio indicators were subjected to wavelet analysis for the period 1984-2004. The 30-90 day variance of the position of the Kuroshio in Tokara Strait shows a seasonfixed nature, with larger amplitudes in the period December-July. The amplitude of the variance in this phenomenon is also modulated by interannual variations, with small variance recorded during 1989-1992, large variance during 1993-1998, and a return to small variance from 1999-2003. This interannual variation is positively correlated with that of Kuroshio volume transport in Tokara Strait. The largest variance during February-April precedes the largest volume transport in April-May by about 1 month, suggesting that mesoscale menders are the forcing of the volume transport increase, not the other way around. Copyright 2006 by the American Geophysical Union.