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首页> 外文期刊>Journal of Physical Oceanography >Measurement of the Rates of Production and Dissipation of Turbulent Kinetic Energy in an Energetic Tidal Flow: Red Wharf Bay Revisited
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Measurement of the Rates of Production and Dissipation of Turbulent Kinetic Energy in an Energetic Tidal Flow: Red Wharf Bay Revisited

机译：高能潮流中湍动能产生和耗散速率的测量：重新研究红码头湾

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Simultaneous measurements of the rates of turbulent kinetic energy (TKE) dissipation (ε) and production (P) have been made over a period of 24 h at a tidally energetic site in the northern Irish Sea in water of 25-m depth. Some ε profiles from ～5 m below the surface to 15 cm above the seabed were obtained using a fast light yoyo (FLY) microstructure profiler, while P profiles were determined from a bottom-mounted high-frequency acoustic Doppler current profiler (ADCP) using the variance method. In homogeneous flow of the kind observed, the turbulence regime should approximate to local equilibrium so that, with no buoyancy forces involved, ε and P are expected to covary with mean values that are equal. The results show a close tracking of ε and P for most of the observational period. For the second tidal cycle, when there was no significant surface wave activity, a mean ratio of ε/P approx= 0.63 +- 0.17 was obtained. Although this is a significant deviation from unity, it is within the range of uncertainty previously reported for the ε measurements. A marked phase lag of between 5 and 20 min between the maximum P and the maximum ε is interpreted using a simple model in terms of the decay rate of TKE. Consideration of inherent instrument noise has enabled an estimate of the lowest P threshold measurable using the variance technique. For the chosen averaging parameters a value of P_(min) ～7 X 10~(-5) W m~(-3) is estimated. Two other significant differences between the two sets of measurements are attributed to errors in the stress estimate. The first is a bias in the estimate of stress resulting from a combination of instrument tilt (1°-3.5°) and surface wave activity. The second are anomalously high stress estimates, covering nearly one-half of the water column at times, which are thought to be due to instrument noise associated with the large wave orbital velocities.
机译：在24小时内，在爱尔兰北部海中潮汐活跃的25 m深度水中，对湍动能（TKE）耗散率（ε）和产气（P）的速率进行了同时测量。使用快速光溜溜（FLY）微结构轮廓仪获得了从海面以下〜5 m到海床以上15 cm的一些ε轮廓，而P轮廓是使用以下方法从底部安装的高频多普勒电流轮廓仪（ADCP）确定的：方差法。在观察到的均匀流动中，湍流状态应近似于局部平衡，因此在不涉及浮力的情况下，预期ε和P的平均值相等。结果表明，在大多数观察期中，ε和P都紧密跟踪。对于第二个潮汐周期，当没有明显的表面波活动时，获得的ε/ P平均比约为0.63±0.17。尽管这与单位制存在显着偏差，但仍在先前针对ε测量报告的不确定性范围内。根据TKE的衰减率，使用简单的模型可以解释最大P和最大ε之间5至20分钟之间明显的相位滞后。考虑到仪器固有的噪声，可以使用方差技术估算出最低的P阈值。对于选择的平均参数，估计值P_（min）〜7 X 10〜（-5）W m〜（-3）。两组测量之间的其他两个显着差异归因于应力估计中的误差。第一个是由于仪器倾斜度（1°-3.5°）和表面波活动的组合而导致的应力估算偏差。第二个是异常高的应力估算值，有时会覆盖近一半的水柱，这被认为是由于与大波浪轨道速度相关的仪器噪声引起的。

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