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Magdalena Andres1, Jae-Hun Park1, Mark Wimbush1,

Kyung Il Chang2, Hiroshi Ichikawa3

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1 Graduate School of Oceanography, University of Rhode Island

2 School of Earth and Environmental Sciences, Seoul National University

3 Institute of Observational Research for Global Change, JAMSTEC

May 24, 2007

The 14th PAMS/JECSS Workshop

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Observational highlights of Kuroshio in the ECS

  • Introduce study area and instruments
  • Velocity
    • mean cross-section
    • depth of maximum velocity
    • near-bottom velocity time series
  • Transport:
    • mean
    • time series
    • spectrum

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Study area (Dec. 2002 – Nov. 2004)

East China Sea

Near PN-line

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Study area

East China Sea

Near PN-line

PIES & CPIES

23 months

ADCPs

13 months

(K.I. Chang)

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  • Emits 12 kHz sound pulses at sea floor

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  • Measure (hourly):
    • τ : echo time from surface
    • P: bottom pressure
    • V: deep horizontal current

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  • Calculate:
    • geostrophic shear from τ (using dynamic height inferred from a lookup table)
    • deep geostrophic flow from P
    • reference deep flow with the current, V

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ABSOLUTE VELOCITY AND TRANSPORT

CPIES

( Current- Pressure- sensor-equipped Inverted Echo Sounder)

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Recirculation

Subsurface velocity core

13-month mean absolute velocity

Countercurrent

Schematic Plan view:

Cross-section:

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Depth of maximum velocity

53%

0.4 – 2.0 m/s

47%

0.3 – 1.1 m/s

Bimodal distribution

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Near-bottom velocity

23-month

means:

C1

C6

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Transport component

24.0 Sv

-0.5 Sv

-4.9 Sv

Positive flow,

countercurrent,

recirculation

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28.9 Sv

3.8 Sv

Net transport

18.5 Sv

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Absolute Velocity (m/s)

Net Transport

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Net transport spectrum

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Net transport spectrum

  • 11 day
    • James et al., 1999
    • Fastest growing instability – spectral model

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  • 15 day
    • Johns et al., 2001
    • Inflow east of Taiwan

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  • 64 day
    • K.I. Chang, B.-H. Lim, J.-H. Park
    • Related to winds over ECS

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Summary of Observational highlights

  • Mean velocity cross-section
    • Positive (northeastward flow)
    • Countercurrent (along slope beneath positive flow)
    • Recirculation (off-shore of positive flow)

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  • Near-bottom velocity
    • Positive flow extends to bottom 50-100 km seaward of shelfbreak
    • Persistent countercurrent along slope
    • High frequency variability on the upper slope

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  • Transport
    • Mean:
      • Net: 18.5 Sv (mse = 0.8 Sv; σ = 4.0 Sv)
      • Positive: 24.0 Sv (mse = 0.9 Sv; σ = 4.4 Sv)
      • Recirculation: -4.9 Sv (mse = 0.3 Sv; σ = 1.8 Sv)
    • Range in net transport: 4 – 29 Sv

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  • Spectral characteristics
    • 64, 15, 11 day peaks in transport

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  • Karen Tracey
  • Gerry Chaplin
  • Capt. Sadao Ishida and the crew aboard the R/V Yokosuka of JAMSTEC
  • Capt. Bong-Won Lee and the crew aboard the R/V Onnuri of KORDI
  • Capt. Sunao Masumitsu and the crew aboard the T/V Kagoshima-maru of Kagoshima University
  • Capt. Jeoung Chang Kim and the crew aboard the R/V Tamyang of Pukyong National University
  • CTD data used in the GEM calculations were kindly provided by the Nagasaki Marine Observatory, Japan Meteorological Agency
  • ONR
  • KORDI
  • JAMSTEC
  • NRL
  • URI/GSO
  • PAMS/JECCS Organizing Committee

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Many thanks to the following individuals and organizations…