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Ocean eddies, fronts, and air-sea exchanges: Observations and high resolution simulations
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Generation and propagation of M2 internal tides modulated by the Kuroshio northeast of Taiwan P-P4-01-S Hang Chang, Institute of Oceanology, Chinese Academy of Sciences Zhenhua Xu* , Institute of Oceanology, Chinese Academy of Sciences Yang Wang, Institute of Oceanology, Chinese Academy of Sciences Baoshu Yin, Institute of Oceanology, Chinese Academy of Sciences Presenter Email: xuzhenhua@qdio.ac.cn |
The variability and energetics of M2 internal tides during their generation and propagation through the Kuroshio background field northeast of Taiwan are investigated using a high-resolution numerical model. The corrugated continental slopes, particularly the I-Lan Ridge and Mien-Hua Canyon, are first identified as the energetic sources of M2 internal tides. The domain-integrated M2 barotropic-to-baroclinic conversion rate under the Kuroshio influence is ~2.35 GW, ~0.9 GW of which is generated at the I-Lan Ridge, ~0.93 GW at the Mien-Hua Canyon and ~0.52 GW at the north shelf. The M2 internal tide generation is influenced by horizontally varying, zonally tilting stratification associated with the Kuroshio, and compared with the ideal simulation initiated with horizontal homogeneous stratification, the conversion rate decreased by ~30% at the I-Lan Ridge but increased within ~10 % at the Mien-Hua Canyon and north shelf. Internal tides from multiple sources interfere to form a three-dimensional baroclinic field. The interference by the internal tides from the Mien-Hua Canyon and north shelf is refracted by the Kuroshio and exhibits a mesoscale gyre pattern, which can explain the frequent occurrence of internal solitary waves. An energetic along-slope tidal beam from the I-Lan Ridge radiates southward against the northward Kuroshio flows with strong vertical displacement in the intermediate layer, which favourably compares with recently reported field measurements. The M2 internal tide energy dissipates primarily near the source sites, and the remaining energy radiates outward over limited distances. Various topographic features and background currents enhance the internal tide dissipation, which induces strong, inhomogeneous vertical mixing. |
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