Kuroshio-Submarine Ridge Interaction: High Frequency Oscillation and Density Overturns.

• Main Authors: Sin-Ya Jheng, 鄭欣雅
• Other Authors: Ming-Huei Chang
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/689a82

碩士 === 國立臺灣海洋大學 === 海洋環境資訊學系 === 101 === Around Taiwan, Kuroshio is an important current with current speed of 1-1.5 m/s. But the effect of islands obstacle to Kuroshio was found to produce recirculation and Vortex Street in the lee of island. From MODIS (Moderate Resolution Imaging Spectroradiometer) image, we found out two signals one is island wake in the lee of Green Island presented by Chang et al. (2013). The other one is surface stripe, which correspond with submarine ridges. In order to understand the interaction between Kuroshio and submarine ridges, we used two moorings to know effect of topography and its background current. And we also had shipboard measurement to connect two sites and measured hydrologic data. The result shown Kuroshio, diurnal tidal current, semi-diurnal tidal current and two-day perturbation in moorings, furthermore, S2 has a high frequency perturbation but S1 didn’t have. We considered that is because of topography. Besides high frequency perturbation, from shipboard measurement we also found out density overturns. It could be observed straightly by density profile. We knew density overturns are relative with turbulence and high frequency perturbation. As inverse Richardson number is large, the density overturns would be there and its dissipation rate of turbulent kinetic energy would be larger which is about O(10-8~10-4), they had good correlation. However, strong density overturns also at high frequency perturbation zone. From above, turbulence and high frequency perturbation is both relative with density overturns, which one is more important factor that is not clear. Finally, we discussed that which factor would interact with topography. Now we consider that Kuroshio is the main factor to interact with topography and generate high frequency perturbation.