- 期刊
黑潮流經海底山引發的紊流混合與硝酸鹽通量變化
Turbulent Mixing and Nitrate Flux Induced by the Kuroshio Over a Seamount
摘要
本研究結合紊流剖面儀（vertical microstructure turbulence profiler, VMP）與潛水式紫外線硝酸鹽分析儀（submersible ultraviolet nitrate analyzer, SUNA）同時在綠島西北方水深200公尺的海底山海域量測紊流與硝酸鹽資料。當黑潮流經海底山之後，在海底山山頭上與下游處產生凱文赫姆茲不穩定波（Kelvin-Helmholtz billow），不穩定波會隨著時間演變成紊流，最終紊流扮演消散黑潮動能及混合海洋內部的角色，故觀測到的紊流動能消散率可達O（10^(-4) W kg^(-1)），垂直渦流擴散率達O（10^(-1) m^2 s^(-1)），強烈的紊流混合造成向表層傳輸之硝酸鹽通量增加至O（10^4 mmol m^(-2) day^(-1)），使下游處（P6站）的硝酸鹽濃度相較於上游處（P1站）大2.7倍。
並列摘要
A vertical microstructure turbulence profiler (VMP) integrated with a submersible ultraviolet nitrate analyzer (SUNA) was deployed to measure turbulence and nitrate concentration simultaneously above a seamount northwest of Green Island. The current shear ensued from the Kuroshio flowing over the seamount triggered trains of Kelvin-Helmholtz billows above the seamount that would extend toward downstream. Kelvin-Helmholtz billows would facilitate turbulent mixing that dissipated energy with turbulent kinetic energy dissipation rates in an order of about O (10^(-4) W kg^(-1)). Moreover, the vertical eddy diffusivity of density can reach O (10^(-1) m^2 s^(-1)), resulting in a high upward vertical nitrate flux of O (10^4 mmol m^(-2) day^(-1)), which makes the nitrate concentration downstream of the seamount (station P6) 2.7 times larger than upstream (station P1).