Forcing Space: An Alternative to Regime Diagrams for Predicting Characteristics of Turbulence in the Ocean Surface Mixing Layer
Forcing Space: An Alternative to Regime Diagrams for Predicting Characteristics of Turbulence in the Ocean Surface Mixing Layer
复制标题
强迫空间：预测海洋表面混合层湍流特征的区域图的替代方法
DOI：
10.1175/jpo-d-21-0145.1
复制
发表时间：
2022
影响因子：
3.5
通讯作者：
Gargett, Ann E.
中科院分区：
文献类型：
--
作者：
Gargett, Ann E.
各种形式的状态图已成为确定海洋表层湍流强迫的主要类型的公认手段。然而，所有拟议的表格都有一些共同的问题，在此表明，这些问题使它们成为实现这一目的的不完美工具。相反，我建议强迫空间组成的表面浮力通量（通常占主导地位的表面热通量）和增长率定义为逆的理论时间尺度增长的朗缪尔环流在非分层水柱。使用沿海的数据，它表明，强迫条件大致恒定的几个小时，在上半平面的强迫空间的位置预测的组织特征的观察到的湍流的范围之间的系统的方式的“纯”对流和那些全深度朗缪尔环流。在这个上半平面中，存在对流尺度速度，并且可以计算表面斯托克斯漂移速度，允许计算斯托克斯尺度速度，两个尺度速度的线性组合提供了对观测到的均方根湍流垂直速度的一致估计。然而，时间依赖性是海洋表层强迫的一个常见特征，如果仅仅是因为表面热通量的日变化（通常很大）。结果表明，近地层湍流响应时变强迫的时间尺度取决于主要的变化是由于风/波或浮力强迫。建议进行相关的建模研究。
Various forms of regime diagrams have become an accepted means of identifying the dominant type of forcing of turbulence in the ocean surface layer. However, all of the proposed forms share a number of issues, demonstrated here, that make them an imperfect tool for this purpose. Instead, I suggest a forcing space consisting of surface buoyancy flux (usually dominated by surface heat flux) and a growth rate defined as the inverse of a theoretical time scale for growth of Langmuir circulations in an unstratified water column. Using coastal data, it is demonstrated that, provided forcing conditions are roughly constant for several hours, location in the upper half-plane of this forcing space predicts organizational characteristics of observed turbulence that range in a systematic way between those of “pure” convection and those of full depth Langmuir circulations. In this upper half-plane, where a convective scale velocity exists and the surface Stokes drift velocity can be computed, allowing calculation of a Stokes scale velocity, a linear combination of the two scale velocities provides a consistent estimate of observed rms turbulent vertical velocity. Time dependence is nevertheless a frequent characteristic of ocean surface layer forcing, if only because of the (usually large) diurnal variation in surface heat flux. It is shown that the time scale of response of surface layer turbulence to time variable forcing depends on whether the major change is due to wind/wave or buoyancy forcing. Relevant modeling studies are suggested.