Quantifying interleaving of water masses and associated turbulence property in the Kuroshio

• Main Authors: Shih-Hong Wang, 王釋虹
• Other Authors: Sen Jan
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/2fssp7

碩士 === 國立臺灣大學 === 海洋研究所 === 106 === To examine the water masses exchanges in the Kuroshio, thousands of high-resolution CTD profiles (salinity, temperature and depth) from the sea surface down to 1000 m depth where acquired by Seagliders across the Kuroshio off the southeast coast of Taiwan. Results from the observations quantify vigorous layered intrusions of South China Sea Water to North Pacific Water transported by the Kuroshio, resulting in the interleaving of the two water masses, particularly in the intermediate layer. The diapycnal spiciness curvature was used to characterize the magnitude of interleaving, suggests that significant interleaving mostly occurred in the intermediate layer between 400 m and 800 m, and the vertical and horizontal length scales were O(10-100) m and O(10-100) km, respectively. The Turner angle, which is a useful parameter for classifying salt fingering and diffusive convection processes, suggests that double diffusion is a dominant process in the interleaving regions. In addition, in order to quantify the turbulence property in the Kuroshio, shipboard hydrographic surveys at the KTV1、KTV2 and KTV3 transect were analyzed. The turbulent kinetic energy dissipation rates (ε) and vertical eddy diffusivity of density (k_ρ) estimated using the Thorpe scale, average value of ε and k_ρ is O(10-7-10-9) W kg-1 and O(10-4-10-3) m2 s-1 at depths between 600 m and 1000 m. This is a plausible cause for the fast mixing of South China Sea Intermediate Water and North Pacific Intermediate Water in the Kuroshio.