Influence of Langmuir Circulation on the Deepening of the Wind-Mixed Layer
Influence of Langmuir Circulation on the Deepening of the Wind-Mixed Layer
复制标题
DOI：
10.1175/2010jpo4494.1
复制
发表时间：
2011-03
影响因子：
3.5
通讯作者：
Y. Noh;Gahyun Goh;S. Raasch
中科院分区：
文献类型：
--
作者：
Y. Noh;Gahyun Goh;S. Raasch
对大涡模拟数据的分析表明，当风应力作用于静止的有分层的混合层时，只有当混合层深度（MLD） h较浅且其浮力跳变ΔB较小时，Langmuir环流（LC）才能显著增强混合层加深。有LC和无LC情况下的夹带速率差随着hΔB/ l2而减小，其中l为LC的速度尺度。对于较大的Rt [=(Nl0/q)2]，有LC与无LC情况下混合长度尺度l的比值接近于1；Rt > ~ 1]，但随着Rt的减小增大到10以上，其中N为Brunt-Vaisala频率，q和10为均匀层湍流的速度尺度和长度尺度。还发现，在LC存在的情况下，分层对垂直混合的影响应该用Rt来参数化，而不是用Ri （=(N/S)2）来参数化，因为速度剪切S不再是旋转的主要来源。
Abstract Analysis of large eddy simulation data reveals that Langmuir circulation (LC) induces a significant enhancement of the mixed layer deepening, only if the mixed layer depth (MLD) h is shallow and the buoyancy jump across it ΔB is small, when simulations are initiated by applying the wind stress to a motionless mixed layer with stratification. The difference in the entrainment rate between the cases with and without LC decreases with hΔB/υL2, where υL is the velocity scale of LC. The ratio of the mixing length scale l between the cases with and without LC is close to 1 for larger Rt [=(Nl0/q)2; Rt > ∼1], but it increases to above 10 with the decrease of Rt, where N is the Brunt–Vaisala frequency and q and l0 are the velocity and length scales of turbulence in the homogeneous layer. It is also found that, in the presence of LC, the effect of stratification on vertical mixing should be parameterized in terms of Rt instead of Ri (=(N/S)2), because velocity shear S is no longer a dominant source of tur...