吕宋海峡不同湍流估算方法的应用对比研究

COMPARATIVE STUDY ON THE APPLICATION OF DIFFETENT TURBULENCE ESTIMATION METHODS IN LUZON STRAIT

由于湍流混合直接观测技术难度大、成本高,很大程度限制湍流混合的研究,所以基于温、盐、流资料估算海洋湍流混合的方法应运而生。本文应用在吕宋海峡观测到的23个自由下降微结构湍流剖面仪观测数据和水文观测数据,首次对目前常用的Gregg-Henyey-Polzin(GHP)细尺度参数化、Mackinnon and Gregg(MG)参数化和Thorpe尺度方法进行比较研究,评估它们的适用性。发现GHP参数化方法能够很好地估算吕宋海峡的湍流混合。虽然GHP参数化方法估算的耗散率总体上要偏弱于观测的结果,但估算和观测的差异在2倍以内的结果占71%,与微结构湍流剖面仪观测到的耗散率在水平分布和垂向分布上呈现出相同的分布特征。基于MG参数化方法发现估算的吕宋海峡西侧1200m以浅的耗散率比观测值大,但总体上呈现出相同的分布特征。另外,MG参数化估算与观测差异在2倍以内的结果占58%。表明相比于GHP参数化方法,MG参数化方法的估算值更偏离观测值。Thorpe尺度方法在估算吕宋海峡的耗散率时,估算和观测的差异在2倍以内的结果仅有30%,70%的估算结果与观测结果相差高出1个量级,空间分布上与观测结果差异较大。对比吕宋海峡湍流混合参数化方法的结果表明GHP参数化方法最优,MG参数化方法其次,Thorpe尺度方法相对GHP和MG参数化方法较差。

Due to the difficulty and high cost of direct observation of turbulence mixing,the study of turbulence mixing is largely limited.Therefore,the method of estimating ocean turbulence mixing based on temperature,salinity,and current data came into being.In this paper,for the first time,we evaluated the applicability of currently used Gregg-Henyey-Polzin(GHP)fine scale parameterization,Mackinnon and Gregg(MG)parameterization,and Thorpe scale methods using data of free-falling microstructural turbulence profilers from 23 observation sites and hydrological observation data in the Luzon strait.It was found that the GHP parameterization method could well estimate the turbulent mixing of Luzon Strait.Although the dissipation rate estimated by the GHP parameterization method is generally weaker than the observation results,the difference between the estimation and observation results within a factor of 2 accounts for 71%,showing the same distribution characteristics with the horizontal and vertical distribution of the dissipation rate observed by the microstructural turbulence profilers.Based on the MG parameterization method,it was found that the dissipation rate of shallow than 1200m on the west side of Luzon Strait was larger than the observed value,but the distribution characteristics were the same on the whole.In addition,the results of MG parametric estimation and observation were within a factor of 2,accounting for 58%.It shows that compared with the GHP parameterization method,the estimated value of MG parameterization method deviates more from the observed value.When the Thorpe scale method was used to estimate the dissipation rate of Luzon Strait,only 30%of the difference between estimation and observation was within a factor of 2,and 70%of the results were more than one order of magnitude,showing the spatial distribution is quite different from the observed results.Comparing the results of turbulent mixing parameterizations in Luzon Strait,showing that the GHP parameterization method is the best,the MG parameterization method is the second,and the Thorpe scale method is inferior to the GHP and MG parameterization methods.