Magdalena%20Andres1,%20Jae-Hun%20Park1,%20Mark%20Wimbush1,

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Observations of Kuroshio Variability in the East
China Sea
May 24, 2007 The 14th PAMS/JECSS Workshop

• Magdalena Andres1, Jae-Hun Park1, Mark Wimbush1,
• Kyung Il Chang2, Hiroshi Ichikawa3
• 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

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

• Emits 12 kHz sound pulses at sea floor
• Measure (hourly)
• t echo time from surface
• P bottom pressure
• V deep horizontal current
• Calculate
• geostrophic shear from t (using dynamic height
  inferred from a lookup table)
• deep geostrophic flow from P
• reference deep flow with the current, V
• ABSOLUTE VELOCITY AND TRANSPORT

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13-month mean absolute velocity
Cross-section
Schematic Plan view
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Depth of maximum velocity
Bimodal distribution
53 0.4 2.0 m/s
47 0.3 1.1 m/s
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Near-bottom velocity
23-month means
C1
C6
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Transport component
Positive flow,
countercurrent,
recirculation
24.0 Sv
-0.5 Sv
-4.9 Sv
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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
• 15 day
• Johns et al., 2001
• Inflow east of Taiwan
• 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)
• 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
• Transport
• Mean
• Net 18.5 Sv (mse 0.8 Sv s 4.0 Sv)
• Positive 24.0 Sv (mse 0.9 Sv s 4.4 Sv)
• Recirculation -4.9 Sv (mse 0.3 Sv s 1.8
  Sv)
• Range in net transport 4 29 Sv
• Spectral characteristics
• 64, 15, 11 day peaks in transport

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Many thanks to the following individuals and
organizations

• 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