A2.4 km long deep-sea mooringwas deployed for 14 months in the Puerto Rico Trench, the deepestpart of the Atlantic Ocean. Below its top buoyancy package, the mooring line held a 200 m long stringof high-resolution temperature sensors and a current meter. Over the instrumented range between6,004 and 6,204 m, waters are very weakly stratified, with local buoyancy frequency equaling about1.9 times the semidiurnal tidal frequency. Besides quiescent waters, the detailed observations showregular vertical turbulent overturning associated with periodic warming and driven by internal tidaland inertial waves. During such episodes, the 4-day and 200 m vertically averaged dissipation rateincreases from approximately 10−11 up to 10−9 m2 s−3, and eddy diffusivity increases from 5 ×10−5 up to 4 × 10−3 m2 s−1. No large-scale shear-driven Kelvin-Helmholtz billows are observed,and free convection seems the dominant primary turbulent overturning mechanism affecting materialredistribution and life in the weakly stratified environment.

中文翻译：

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波多黎各海沟内波对流混合

一条 2.4 公里长的深海系泊设备在大西洋最深处的波多黎各海沟部署了 14 个月。在其顶部浮力包下方，系泊缆绳装有一串 200 m 长的高分辨率温度传感器和一个电流表。在 6,004 至 6,204 m 之间的仪器测量范围内，水域分层非常弱，局部浮力频率约为半日潮汐频率的 1.9 倍。除了静止水域外，详细的观测还显示出与周期性变暖相关并由内部潮汐大陆惯性波驱动的定期垂直湍流翻转。在这些事件中，4 天和 200 m 垂直平均耗散率从大约 10−11 增加到 10−9 m2 s−3，涡流扩散率从 5 × 10−5 增加到 4 × 10−3 m2 s− 1.