Modeled Oceanic Response and Sea Surface Cooling to Typhoon Kai-Tak

  • Author(s): Yu-Heng Tseng, Sen Jan, David E. Dietrich, I-I Lin, Ya-Ting Chang, and Tswen-Yung Tang
  • DOI:

    10.3319/TAO.2009.06.08.02(IWNOP)

  • Keywords: Air-sea interaction, Typhoon, Upwelling

 

Abstract

An ocean response to typhoon Kai-Tak is simulated using an accurate fourth-order, basin-scale ocean model. The surface winds of typhoon Kai-Tak were obtained from QuikSCAT satellite images blended with the ECMWF wind fields. An intense nonlinear mesoscale eddy is generated in the northeast South China Sea (SCS) with a Rossby number of O(1) and on a 50 - 100 km horizontal scale. Inertial oscillation is clearly observed. Advection dominates as a strong wind shear drives the mixed layer flows outward, away from the typhoon center, thus forcing upwelling from deep levels with a high upwelling velocity (> 30 m day-1). A drop in sea surface temperature (SST) of more than 9¢XC is found in both observation and simulation. We attribute this significant SST drop to the influence of the slow moving typhoon, initial stratification and bathymetry-induced upwelling in the northeast of the SCS where the typhoon hovered.

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