Comparison of structure and turbulent mixing between lateral and leading-edge river plume fronts: Microstructure observations from a T-REMUS AUV
Comparison of structure and turbulent mixing between lateral and leading-edge river plume fronts: Microstructure observations from a T-REMUS AUV
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横向和前缘河流羽流锋之间的结构和湍流混合比较：T-REMUS AUV 的微观结构观察
DOI：
10.1016/j.ecss.2023.108234
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
Cole, Kelly
中科院分区：
文献类型：
--
作者：
Delatolas, Nikiforos;MacDonald, Daniel G.;Goodman, Louis;Whitney, Michael;Huguenard, Kimberly;Cole, Kelly
T-REMUS 自主水下航行器 (AUV) 在不同深度的 10 个交叉前沿横断面中航行，对康涅狄格河羽流的潮汐脉冲的能量前沿区域进行了采样。同步和高分辨率的水文、微观结构、速度和反向散射观测允许在传播锋面的参考系中创建锋面结构和湍流混合的详细视图。锋面的水平密度梯度约为 18.5 kg m−4，水平方向仅 0.7 m，下降流速度为 0.17 m/s。一致地确定了三个连续的区域。第一个 O (10 m) 宽的下降流区域，其中浮力羽流被迫向下，从而形成高能锋头，向下延伸至 6 m 深度，TKE 耗散率 (ε) 为 10−3m2/s3 量级。在下降流区到 O (100 m) 之外，观察到一个过渡区，其特征是大量夹带环境水。该区域具有高振幅和高频率密度异常 (σθ) 变化，与升高但降低的湍流动能耗散率 (ε) 一致，其范围在 10−4 和 10−5m2/s3 之间。距离前方 100 米之外，稳定的分层、高 Ri 值和低 Reb 值抑制了不稳定性的增长并减少了湍流混合。在这个稳定的内部区域，羽流底部浅化至 2 m 深度，ε 进一步下降，从 10−5 降至 10−7m2/s3。在长岛海峡周围水域，ε 的范围在 10−6 和 10−7m2/s3 之间。当锋面从横向边界（羽流主要沿锋面方向）转变为羽流前缘（羽流主要沿横向锋面方向）时，σθ和ε的横向锋面分布没有显着变化。在这两种情况下，由于周围潮汐速度较强，前端出现了明显的辐合。使用与前部下降流区域相关的速度和长度尺度对观察到的 ε 值以及之前四项大型和中型羽流研究中的 ε 值进行无量纲化。有效归一化表明局部动力学主要控制近额叶区域的 ε。
The energetic frontal region of the tidally pulsed Connecticut River plume was sampled with the T-REMUS Autonomous Underwater Vehicle (AUV) which navigated ten cross-front transects at various depths. Synchronous and high resolution hydrographic, microstructure, velocity and backscatter observations allowed the creation of detailed views of frontal structure and turbulent mixing in the reference frame of the propagating front. The front was defined by a sharp horizontal density gradient of ∼18.5 kg m−4across only 0.7 m in the horizontal, and strong downwelling velocities of 0.17 m/s. Three successive zones were consistently identified. The first O (10 m) wide downwelling zone in which buoyant plume water was forced downward, thereby forming a highly energetic frontal head that extended down to 6 m depth and had TKE dissipation rates (ε) of order 10−3m2/s3. Beyond the downwelling zone to O (100 m), a transition zone was observed, characterized by substantial entrainment of ambient water. This zone had high amplitude and high frequency density anomaly (σθ) variability consistent with elevated but decreasing turbulent kinetic energy dissipation rates (ε) which ranged between 10−4and 10−5m2/s3. Beyond O (100 m) from the front, stable stratification, high Ri values, and low Rebvalues, suppressed the growth of instabilities and diminished turbulent mixing. In this stable interior region the plume base shoaled to 2 m depth and ε decreased further, from 10−5to 10−7m2/s3. In ambient Long Island Sound waters, ε ranged between 10−6and 10−7m2/s3. The cross-front distributions of σθand ε did not change substantially as the front transformed from a lateral boundary, where plume flow was primarily in the along-front direction, to one that was at the leading edge of the plume, where plume flow was mostly in the cross-front direction. In both cases, a significant convergence was present at the front due to strong ambient tidal velocities. The observed ε values and those from four previous studies of large and mid-sized plumes were nondimensionalized using the velocity and length scales associated with the downwelling region at the front. The effective normalization suggests that local dynamics primarily control ε in the near-frontal region.
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DOI：
--
发表时间：
2019
期刊：
--
影响因子：
--
作者：
R. Lueck
通讯作者：
R. Lueck
河流羽流前沿的相干结构和混合
DOI：
10.1002/9781118527221.ch23
发表时间：
2013
期刊：
Journal of Applied Meteorology
影响因子：
--
作者：
A. Horner‐Devine;C. Chickadel;D. MacDonald
通讯作者：
D. MacDonald
浮力表面羽流中的湍流和夹带
影响因子：
--
作者：
D. Luketina;J. Imberger
通讯作者：
J. Imberger
影响因子：
2.8
作者：
E. Levine;L. Goodman;J. O’Donnell
通讯作者：
E. Levine;L. Goodman;J. O’Donnell
影响因子：
3.7
作者：
G. Jirka;M. Arita
通讯作者：
M. Arita