TOPEX/POSEIDON-derived space-time variations of the Kuroshio Current: applications of a gravimetric geoid and wavelet analysis

SUMMARY Using TOPEX/POSEIDON (T/P) altimeter data and a gravimetric geoid, we derived 7-year time-series of Kuroshio’s volume transport, axis velocity, width and axis locations northeast and southeast of Taiwan. For northeastern and southeastern Taiwan, the mean volume transports are 19 and 26 Sv, the mean widths are 112 and 96 km and the mean axis velocities are 50 and 82 cm s −1 , respectively. The T/P-derived volume transports agree well with in situ result. Drifter d21160 almost passes through the T/P-derived axes of the Kuroshio. The time-series show intraseasonal, semi-annual, annual and interannual variations but the frequency characteristics at the two locations are different owing to monsoon, bottom topography and other factors. Wavelet analyses show that the amplitudes and phases of the frequency components vary with time. A biennial component is found in almost all time-series and may be excited by the tropical quasi-biennial oscillation of the atmosphere. The volume transport northeast of Taiwan has a positive correlation (0.6) with ENSO with a 1-month lag, and both the volume transport and velocity southeast of Taiwan have a negative correlation (−0.6) with ENSO with a 9‐ 10 months lead.

[1]  S. Chao,et al.  The Kuroshio edge exchange processes (KEEP) study — an introduction to hypotheses and highlights , 2000 .

[2]  Joe Wang,et al.  The exchange of Kuroshio and East China Sea shelf water , 1990 .

[3]  C. Hwang,et al.  Fourier and wavelet analyses of TOPEX/Poseidon-derived sea level anomaly over the South China Sea: A contribution to the South China Sea Monsoon Experiment , 2000 .

[4]  H. Moritz.  Advanced Physical Geodesy , 1980 .

[5]  H. Hurlburt,et al.  Coupled dynamics of the South China Sea, the Sulu Sea, and the Pacific Ocean , 1996 .

[6]  Q. Zheng,et al.  A Numerical Simulation of Wind Stress and Topographic Effects on the Kuroshio Current Path near Taiwan , 1996 .

[7]  R. Rapp,et al.  Preliminary estimates of Gulf Stream characteristics from TOPEX data and a precise gravimetric geoid , 1994 .

[8]  Chang-Kou Tai,et al.  Estimating the surface transport of meandering oceanic jet streams from satellite altimetry : Surface transport estimates for the Gulf Stream and Kuroshio Extension , 1990 .

[9]  B. Tapley,et al.  The Grace Mission: Status And Future Plans , 2001 .

[10]  B. Parsons,et al.  Global derivation of marine gravity anomalies from Seasat, Geosat, ERS-1 and TOPEX/POSEIDON altimeter data , 1998 .

[11]  V. Zlotnicki.  Quantifying time-varying oceanographic signals with altimetry , 1993 .

[12]  Hiroshi Ichikawa,et al.  Temporal and spatial variability of volume transport of the Kuroshio in the East China Sea , 1993 .

[13]  Dongxiao Zhang,et al.  The Kuroshio East of Taiwan: Moored Transport Observations from the WOCE PCM-1 Array , 2001 .

[14]  Henry F. Diaz,et al.  Global climatic anomalies associated with extremes in the Southern Oscillation , 1989 .

[15]  N. K. Pavlis,et al.  The Development of the Joint NASA GSFC and the National Imagery and Mapping Agency (NIMA) Geopotential Model EGM96 , 1998 .

[16]  B. Qiu,et al.  Seasonal and interannual variability of the North Equatorial Current, the Mindanao Current, and the Kuroshio along the Pacific western boundary , 1996 .

[17]  C. Torrence,et al.  A Practical Guide to Wavelet Analysis. , 1998 .

[18]  Gilles Reverdin,et al.  Global high-resolution mapping of ocean circulation from TOPEX/Poseidon and ERS-1 and -2 , 2000 .

[19]  H. Uchida,et al.  Comparison of Kuroshio surface velocities derived from satellite altimeter and drifting buoy data , 1998 .

[20]  P. A. Cross,et al.  Lecture notes in Earth sciences: Vol. 12. S. Turner (Editor), Applied Geodesy VIII, Springer, Berlin, F.R.G., 1987, 393pp, DM78.00, ISBN 3 540 182195 , 1989 .

[21]  Ingrid Daubechies,et al.  Ten Lectures on Wavelets , 1992 .

[22]  C. Hwang.  A study of the Kuroshio's seasonal variabilities using an altimetric-gravimetric geoid and TOPEX/POSEIDON altimeter data , 1996 .

[23]  Cheinway Hwang,et al.  Circulations and eddies over the South China Sea derived from TOPEX/Poseidon altimetry , 2000 .

[24]  H. Mitsudera,et al.  On the western boundary currents in the Philippine Sea , 1998 .

[25]  C. Hwang.  Analysis of some systematic errors affecting altimeter-derived sea surface gradient with application to geoid determination over Taiwan , 1997 .

[26]  A. E. Gill.  Atmosphere-Ocean Dynamics , 1982 .

[27]  B. Qiu.  Seasonal Eddy Field Modulation of the North Pacific Subtropical Countercurrent: TOPEX/Poseidon Observations and Theory , 1999 .

[28]  William E. Johns,et al.  The Kuroshio East of Taiwan: Modes of Variability and Relationship to Interior Ocean Mesoscale Eddies , 2001 .

[29]  Praveen Kumar,et al.  Wavelet Analysis in Geophysics: An Introduction , 1994 .

[30]  P. Chu,et al.  South China Sea isopycnal surface circulation , 2000 .

[31]  Y. Hsueh.  The Kuroshio in the East China Sea , 2000 .

[32]  T. Tang,et al.  The flow pattern north of Taiwan and the migration of the Kuroshio , 2000 .

[33]  Kevin Hamilton,et al.  The quasi‐biennial oscillation , 2001 .

[34]  W. Johns,et al.  Sea surface slope as an estimator of the Kuroshio volume transport east of Taiwan , 2001 .

[35]  E. J. Christensen,et al.  TOPEX/POSEIDON mission overview , 1994 .