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Generation and Propagation of M 2 Internal Tides Modulated by the Kuroshio Northeast of Taiwan
Author(s) -
Chang Hang,
Xu Zhenhua,
Yin Baoshu,
Hou Yijun,
Liu Yahao,
Li Delei,
Wang Yang,
Cao Shengshan,
Liu Antony K.
Publication year - 2019
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
eISSN - 2169-9291
pISSN - 2169-9275
DOI - 10.1029/2018jc014228
Subject(s) - internal tide , baroclinity , barotropic fluid , canyon , geology , stratification (seeds) , internal wave , ridge , continental shelf , oceanography , isopycnal , mesoscale meteorology , bathymetry , geomorphology , paleontology , seed dormancy , botany , germination , dormancy , biology
Abstract The variability and energetics of M 2 internal tides during their generation and propagation through the Kuroshio flows 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 M 2 internal tides. The domain‐integrated M 2 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 M 2 internal tide generation is influenced by the horizontally varying, zonally tilting stratification associated with the Kuroshio. In this situation, the conversion rate decreases by ~30% at the I‐Lan Ridge but increases to within ~10% at the Mien‐Hua Canyon and north shelf, in comparison to the simulation initiated with horizontal homogeneous stratification. 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 (TBKC) from the I‐Lan Ridge radiates southward against the northward Kuroshio flows, causing strong vertical displacement, which favorably compares with recently reported field measurements. The M 2 internal tide energy dissipates primarily near the source sites, and the remaining energy radiates outward over limited distances. Complex topographic features and background currents enhance the internal tide dissipation, which induces strong, inhomogeneous diapycnal mixing.