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Yu-Lin Eda Chang National Taiwan Normal University

Critical wind condition and current reversals in the Taiwan Strait . Yu-Lin Eda Chang National Taiwan Normal University. Co-author: L.-Y. Oey , Y.-C. Lin, M.-C. Chang, and S. Varlamov. Shipwreck incident near Xiamen. 2012/03/15. Debris were found at Tauyuan. 2012/04/01. 50.

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Yu-Lin Eda Chang National Taiwan Normal University

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  1. Critical wind condition and current reversals in the Taiwan Strait Yu-Lin Eda Chang National Taiwan Normal University Co-author: L.-Y. Oey, Y.-C. Lin, M.-C. Chang, and S. Varlamov

  2. Shipwreck incident near Xiamen 2012/03/15 Debris were found at Tauyuan 2012/04/01 50 Mean Transport : 1.8 Sv Winter:0.9 Sv[Wang et al, 2003] Winter: 0.12Sv [Lin et al, 2005] 200 Why and how could the cross-strait flow occur during northeasterly monsoon ?

  3. Tracer simulation with/without Stoke drift Difference No wave With wave

  4. uo = -(g/f)./y + oy/(fE) • vo = -(g/r)./y + oy/(fE).[1 + fE/(Hr)] • Critical Along-Strait Wind • vo=0, voy ~ -1.2×10-4 (m2 s-2) [~ -10m/s] • uo=0, uoy ~ -0.68×10-4 (m2 s-2) [~ -7m/s] Analytical model: Follow the quasi-steady, depth average: rvA = -g/y + oy/H r ~ 1.6×10-5 (s-1) /y ~ -4.5×10-7

  5. EOF analysis : mode 1 Corr(oy(vo), PC)=0.93 Corr(oy(vo), PC)=0.83 • vo = -(g/r)./y + oy/(fE).[1 + fE/(Hr)]

  6. EOF analysis : mode 2 Corr(oy, PC)=−0.52 Corr(oy, PC)=−0.68 u ~ uPG + uwind + uPG’ vo= -(g/r)./y + oy/(fE).[1 + fE/(Hr)] vm~ vo + voPG Corr(PCη, VoPG)=0.70 Corr(PCuv, VoPG)=0.61

  7. Summary • Flow tends to be southwestward if the Northeasterly wind stress is stronger than |1.2×10-4| m2 s-2 • Flow tends to be northeastward if the Northeasterly wind stress is weaker than |0.68×10-4| m2 s-2 • The model tracer-tracking simulations support such a scenario, and it demonstrates the importance of wave-induced Stokes drift in advecting the debris to the near-coast regions • The first two modes of EOF account for 70~85% total variance. The first mode explains the quasi-steady pressure gradient and wind forced velocity. The second mode is affected by the fluctuating pressure gradient

  8. ATOP - Advanced Taiwan Ocean Prediction System Resolution: 0.1 x0.1 deg x 41 sigma levels Free Running from 1987 to 2011 Forecast: 2012/Jan-present NCEP-GFS wind, -7days hincast~7days forecast (No data assimilation on the shelf) Oey, et al, 2012

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