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Journal of Oceanography

, Volume 64, Issue 6, pp 937–950 | Cite as

Study of the Kuroshio/Ryukyu Current system based on satellite-altimeter and in situ measurements

  • Magdalena Andres
  • Jae-Hun Park
  • Mark Wimbush
  • Xiao-Hua Zhu
  • Kyung-Il Chang
  • Hiroshi Ichikawa
Original Articles

Abstract

Data from satellite altimeters and from a 13-month deployment of in situ instruments are used to determine an empirical relationship between sea-level anomaly difference (SLA) across the Kuroshio in the East China Sea (ECS-Kuroshio) and net transport near 28°N. Applying this relationship to the altimeter data, we obtain a 12-year time series of ECS-Kuroshio transport crossing the C-line (KT). The resulting mean transport is 18.7 ± 0.2 Sv with 1.8 Sv standard deviation. This KT is compared with a similarly-determined time series of net Ryukyu Current transport crossing the O-line near 26°N southeast of Okinawa (RT). Their mean sum (24 Sv) is less than the mean predicted Sverdrup transport. These KT and RT mean-flow estimates form a consistent pattern with historical estimates of other mean flows in the East China Sea/Philippine Basin region. While mean KT is larger than mean RT by a factor of 3.5, the amplitude of the KT annual cycle is only half that of RT. At the 95% confidence level the transports are coherent at periods of about 2 years and 100–200 days, with RT leading KT by about 60 days in each case. At the annual period, the transports are coherent at the 90% confidence level with KT leading RT by 4–5 months. While the bulk of the Kuroshio enters the ECS through the channel between Taiwan and Yonaguni-jima, analysis of satellite altimetry maps, together with the transport time series, indicates that the effect of mesoscale eddies is transmitted to the ECS via the Kerama Gap southwest of Okinawa. Once the effect of these eddies is felt by the ECS-Kuroshio at 28°N, it is advected rapidly to the Tokara Strait.

Keywords

Kuroshio Ryukyu Current volume transport East China Sea Tokara Strait Kerama Gap eddies inverted echo sounder ADCP satellite altimeter 

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Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  • Magdalena Andres
    • 1
  • Jae-Hun Park
    • 1
  • Mark Wimbush
    • 1
  • Xiao-Hua Zhu
    • 2
  • Kyung-Il Chang
    • 3
  • Hiroshi Ichikawa
    • 4
  1. 1.Graduate School of OceanographyUniversity of Rhode IslandNarragansettUSA
  2. 2.State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of OceanographyState Oceanic AdministrationHangzhouChina
  3. 3.Research Institute of Oceanography/School of Earth and Environmental SciencesSeoul National UniversitySeoulKorea
  4. 4.Institute of Observational Research for Global ChangeJapan Agency for Marine-Earth Science and TechnologyKanagawaJapan

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