北太平洋低纬度西边界流系湍流混合的微观结构测量和参数化方法评估

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中文摘要：湍流混合在调控海洋垂向物质、能量交换以及气候变化中都起着重要作用,尤其是在北太平洋低纬度西边界流系,湍流混合通过调节温跃层及海气相互作用,在西太平洋暖池结构及演化和厄尔尼诺与南方涛动的发生、发展中都起着关键作用.然而,由于湍流观测的高风险性和高费船时特征,直接的湍流观测资料非常稀缺,因此,对该海域的湍流混合认知大多数来自细尺度参数化估计.鉴于湍流的高时变特征及该海域海洋环流结构的复杂性及西边界流区动力环境的特殊性,验证不同细尺度参数化方法对该海域湍流估算的适用性对于我们准确了解该海域的垂向混合特征、提升其在数值模拟的精度具有重要作用.本研究利用2020年9月在北太平洋低纬度西边界流系沿130°E,10°～18°N进行的直接的微结构观测剖面仪和同期获取的细尺度温盐流测量,研究该海域湍流混合的特征及两种常用的参数化方法——GHP(Gregg-Henyey-Polzin)参数化方法、MG(MacKinnon-Gregg)参数化方法在该海域的适用性.观测结果表明,该海域上200 m湍流混合总体较强,直接观测得到的平均湍动能耗散率约为10-8W/kg.在温跃层中,某些站点观测的湍动能耗散率可达10-7W/kg,特别是在14°N附近,24.5 σθ与25.5 σθ之间发现一块强湍动能耗散区,初步分析表明其机制与全日内潮的参数化次谐波不稳定有关.参数化评估结果显示,MG方法与观测值相差0.5个数量级的比例为95％,而基于应变的GHP方法和基于剪切的GHP方法与观测值相差0.5个数量级的比例分别为55％和58％,表明MG方法能较好地估算低纬度西边界流系的湍流混合特征并在水平分布和垂直分布表现出一致的分布特征.该评价结果可为研究人员选择细尺度参数化来探讨北太平洋低纬度西边界流系湍流混合的强度和空间分布提供有益参考.

外文标题：MICROSTRUCTURE MEASUREMENT AND PARAMETERIZATION FOR THE ASSESSMENT OF TURBULENT MIXING IN THE NORTH PACIFIC LOW-LATITUDE WESTERN BOUNDARY CURRENT SYSTEM

外文摘要：Turbulent mixing plays an important role in regulating the oceanic vertical material and energy exchanges as well as climate change,especially in the North Pacific low-latitude Western Boundary Current System,where turbulent mixing plays a key role in the structure and evolution of the Western Pacific Warm Pool as well as in the onset and development of the El Nino and the Southern Oscillation,through the regulation of the thermocline and the air-sea interactions.However,direct turbulence observations are scarce due to the high-risk and high ship-time characteristics of turbulence observations,and thus most of the knowledge of turbulent mixing in this region derives from fine-scale parameterized estimates.In view of the high time-varying turbulence,complex ocean circulation structure,and unique dynamical environment in the western boundary current zone,validating the applicability of various fine-scale parameterization methods for turbulence estimation is crucial for understanding vertical mixing characteristics and improving numerical simulation accuracy.In this study,we applied the direct microstructure observation profiler and the fine-scale thermohaline flow measurements in September 2020 along 130°E at 10°～18°N in the North Pacific low-latitude Western Boundary Current System,to investigate the characteristics of turbulent mixing and the applicability of the two commonly used parameterization methods:the GHP(Gregg-Henyey-Polzin)parameterization and MG(MacKinnon-Gregg)parameterization.Results indicate that the turbulent mixing in the upper 200 m was strong in total,with an average turbulent kinetic energy dissipation rate of about 10-8 W/kg.In the thermocline,the observed turbulent energy dissipation rate reached 10-7 W/kg at some stations,especially near 14°N,and a strong turbulent energy dissipation region was found between 24.5 σθ and 25.5 σθ.Preliminary analysis suggested that the mechanism was related to the parametric subharmonic instability of the diurnal internal tide.The results of the parameterization evaluation show that the proportion of difference by 0.5 orders of magnitude between the MG method and the observations was 95％,while those between the strain-based GHP method and the shear-based GHP method,and the observations were 55％and 58％,respectively,which suggests that the MG method is able to better estimate the turbulent mixing characteristics of the low-latitude Western Boundary Current System and exhibits consistent features in the horizontal and vertical distributions.The results of this study provided a useful reference for researchers to select a fine-scale parameterization to explore the intensity and spatial distribution of turbulent mixing in the low-latitude western boundary current system in the North Pacific Ocean.

外文关键词：

North Pacific low-latitude western boundary current systemmicrostructure observationsGHP parameterizationMG parameterization

作者：

孙斌、周慧、汪嘉宁、杨文龙、刘恒昌、于晓彤、董焕河

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作者单位：

山东科技大学数学与系统科学学院山东青岛 266590

中国科学院海洋研究所山东青岛 266071

中国科学院大学北京 100049

崂山实验室海洋动力过程与气候功能实验室山东青岛 266237

海军研究院天津 300061

地理信息工程国家重点实验室陕西西安 710054

北京应用气象研究所北京 100029

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关键词：

北太平洋低纬度西边界流系微结构观测 GHP参数化方法 MG参数化方法

基金：

国家自然科学基金项目崂山实验室科技创新项目中国科学院战略性优先发展研究计划"一带一路"国际科学组织联盟联合研究合作专项资助国家自然科学基金项目

项目编号：

42276012号LSKJ202202502号XDB42000000号ANSO-CR-KP-2022-08号NORC2020-09

出版年：

2024

DOI：

10.11693/hyhz20231200269

海洋与湖沼

中国海洋湖沼学会中国科学院海洋研究所

海洋与湖沼

CSTPCD北大核心

影响因子：0.737

ISSN：0029-814X

年,卷(期)：2024.55(4)

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