In the presence of a mean flow, theory and models for internal tide generation at small‐amplitude topography show (a) internal tides produce a net momentum flux that extends to the surface and (b) fluxes are directed preferentially upstream. Here, we observe internal tides propagating into the North Equatorial Countercurrent during two spatial surveys near a submarine ridge. On the second survey during a diurnal spring tide, we note elevated shear upstream of the ridge below 112 m with corresponding low Richardson numbers, which suggests the internal waves are dissipating due to shear instability. Reduced amplitudes are noted above 150 m. Internal tidal motions were isolated by performing a phase average over a wavelength upstream of the topography. Momentum flux convergence and divergence are noted upstream of the ridge, have a similar magnitude to mean flow acceleration terms, and are about 10% of the largest mean flow terms. The internal tides were noted upstream and appeared weaker downstream, but due to the topographic wake similar calculations could not be performed downstream. Tall, steep topography and strong equatorial currents are found throughout the low‐latitude western Pacific, which suggests such infrequently observed internal tide flux divergences may be commonly contributing to the momentum of mean flows.

中文翻译：

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来自帕劳梅里尔岛附近海底海岭北赤道逆流上游内潮的动量通量收敛

在存在平均流量的情况下，小振幅地形上的内部潮汐产生的理论和模型表明：（a）内部潮汐产生的净动量通量延伸到表面，并且（b）通量优先指向上游。在这里，我们在海底山脊附近的两次空间勘测中观察到内部潮汐向北赤道逆流传播。在日春季潮期间进行的第二次调查中，我们注意到山脊上游的剪切力在112 m以下，并具有相应的低Richardson数，这表明由于剪切不稳定性，内部波正在消散。在150 m以上注意到振幅减小。通过在地形上游波长范围内执行相位平均，可以隔离内部潮汐运动。动量通量收敛和发散在山脊的上游，具有与平均流量加速项相似的大小，并且约为最大平均流量项的10％。内部潮汐出现在上游，下游显得较弱，但是由于地形唤醒，下游无法进行类似的计算。在整个低纬度西太平洋地区都发现高大，陡峭的地形和强烈的赤道洋流，这表明这种很少见的内部潮汐通量发散通常可能有助于平均流的动量。