Slow subinertial variations in Antarctic Bottom Water (AABW) are investigated interacting with internal waves and associated turbulent mixing in the Puerto Rico Trench (PRT), northwest Atlantic. Just below the PRT’s top at 5,500 m, a deep-sea mooring was deployed for 14 months. Around 6,100 m, the line held a 200 m long string of 101 high-resolution temperature sensors and a current meter. Around 8,250 m, a similar string held 102 sensors, of which the lowest was 9 m above the bottom. As was measured with shipborne conductivity-temperature-depth profiling down to 7,150 m, PRT waters are very weakly stratified, with local mean buoyancy frequency equaling 1–1.7 times the semidiurnal tidal frequency. The observations show alternating quiescent and relatively turbulent periods that correspond with relatively cooler and warmer AABW, respectively. Over the 2,100 m distance between the two temperature strings, only semidiurnal tidal variations significantly correlate with an average phase difference of 90◦ (3 h) for the entire recording period. This suggests a dominant baroclinic rather than a barotropic coupling. During quiescent periods, the vertical internal wave scale is rather small with out-of-phase tidal motions between the two data sets and vertical excursions of 40 m. During turbulent periods, internal wave motions at all frequencies are close to in phase between the two data sets, suggesting fast vertical propagation with excursions exceeding 200 m. Increased subinertial energy levels, probably reflecting trapped internal waves, are found near the bottom during such periods. It is suggested that internal wave turbulence dominates the deep-sea transport of heat and suspended materials over the entire PRT height and possibly beyond.

中文翻译：

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AABW-传输变化及其对波多黎各海沟顶部和底部之间内部波浪运动的影响

研究了南极底水 (AABW) 的缓慢亚惯性变化与大西洋西北部波多黎各海沟 (PRT) 中的内波和相关湍流混合的相互作用。在 PRT 顶部 5,500 m 的正下方，部署了深海系泊设备 14 个月。在大约 6,100 m 处，这条线路上有 200 m 长的串，由 101 个高分辨率温度传感器和一个电流表组成。在大约 8,250 m 处，一根类似的绳子装有 102 个传感器，其中最低的在底部上方 9 m 处。正如船载电导率-温度-深度剖面测量到 7,150 m，PRT 水域分层非常弱，局部平均浮力频率等于半日潮汐频率的 1-1.7 倍。观测显示交替的静止和相对湍流时期分别对应于相对较冷和较暖的 AABW。在两个温度串之间的 2,100 m 距离内，只有半日潮汐变化与整个记录期间 90°（3 h）的平均相位差显着相关。这表明主要的斜压耦合而不是正压耦合。在静止期间，垂直内波尺度相当小，两个数据集之间存在异相潮汐运动，垂直偏移为 40 m。在湍流期间，两个数据集之间所有频率的内波运动都接近同相，这表明偏移超过 200 m 的快速垂直传播。在此期间，在底部附近发现了增加的亚惯性能级，可能反映了被困的内波。