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水下滑翔机观测数据处理及南海北部中尺度涡演变过程个例研究
Alternative TitleUnderwater glider observation data processing and individual case study of mesoscale eddy evolution in the northern South China Sea
褚福硕
Subtype博士
Thesis Advisor庞重光
2022-08-05
Degree Grantor中国科学院大学
Place of Conferral中国科学院海洋研究所
Degree Name理学博士
Degree Discipline物理海洋学
Keyword水下滑翔机 热滞后修正 质量控制 中尺度涡
Abstract

水下滑翔机作为一种新型海洋观测平台,具有低能耗、长航程、运行成本低等优点。随着越来越多不同类型的水下滑翔机应用在海洋中,利用其搭载的多种传感器获取的海洋数据需要进行系统性处理和质量控制。本文利用中国科学院沈阳自动化研究所研制的“海翼”号水下滑翔机,对获取的温度、电导率数据进行处理,并利用质量控制后的水下滑翔机数据开展了南海中尺度涡数据分析工作,结合其他观测资料及模式资料对南海北部中尺度结构和演化特征进行动力学分析。

本文首先研究了水下滑翔机获得的温度、电导率观测数据的处理方法。重新评估了水下滑翔机穿越跃层时导致的热滞后效应,常规修正方法对于大温差和低采样的热滞后修正表明存在过度修正和欠修正现象,根据盐度梯度随深度的变化以及水下滑翔机垂直速度将数据分段,本文分析发现温度偏差导致热滞后修正在不同深度处修正效果不同,因此提出一种基于Morison算法以及海洋物理环境场的优化分段修正算法,改进了大温差、低采样的盐度剖面偏差,在对所有剖面应用优化算法后,典型盐度修正比从1.56改进到2.04,上下行剖面盐度差从0.011降低到0.006。本文介绍了针对“海翼”水下滑翔机的实时质量控制流程,包括时间检查、连续性检查、语法检查、尖峰检查、梯度检查、温盐曲线检查等。通过以上质量等级检查以及数据后处理后,将标记好的数据设定不同的处理级别输出科学格式文件,并以可视化软件展示。

接着本文基于“海翼”水下滑翔机获得的温盐场及卫星定位资料评估了深度平均流,根据船载ADCP误差分析法估算深度平均流误差约为0.036 m/s,并选取南海北部的一组试验对绝对地转流进行评估。本文还分析了另外一个南海北部反气旋涡旋的垂直温盐剖面,气旋涡的影响深度达到了1000 m左右,涡旋的最大温度异常在120 m处;温度异常在50 m以上较小,涡旋的最大盐度异常出现在混合层中。

最后本文结合水下滑翔机数据处理和测流方法,分析了南海北部西沙群岛附近一个气旋涡的演化过程。通过数据订正以及概率密度统计分析,分辨出了一个气旋涡,并呈现出不均匀的温度结构和高盐度值(>34.7)。涡的振幅和半径在其生长阶段持续增加,在穿过西沙群岛后逐渐减弱,并在越南西部迅速消散。水下滑翔机及Argo数据与HYCOM模式数据吻合较好,证明了利用模式数据研究南海中尺度涡的可靠性。VDI(vorticity and deformation index)与OW(Okubo–Weiss)参数结合卫星高度计资料表明涡在到达西沙群岛后涡区仍由涡度场主导。BC(baroclinic)和 BT(barotropic)水平分布结果表明了在涡旋的生成阶段从正压和斜压不稳定中获得能量;在耗散阶段,冷涡北部的BT和BC为负值,坡底阻力加强了平均水平速度切变从而抑制了横向速度扰动的增长;BT在冷涡南部和东部为正值;BC在冷涡东部为正值,表明了由于地形特征导致的不稳定和涡旋的生成,进一步分析发现涡在到达西沙群岛后风应力旋度不是导致涡耗散的原因,EKE能量收支平衡方程与Thorpe尺度参数化定量分析了冷涡在遇到西沙群岛后的涡动能耗散过程主要通过小尺度湍流过程完成。VDI与BT、BC的相关性分析发现在涡旋生长阶段,VDI指数可以指示涡旋的生长; 在涡旋耗散阶段,VDI指数与BC与BT无明显相关性,其主要由于气旋涡在到达西沙群岛后并未发生明显形变过程,VDI指数仍主要受涡度变化影响。

Other Abstract

As a new type of ocean observation platform, underwater glider has the advantages of low energy consumption, long range and low operating cost. As more and more different types of underwater gliders are used in the ocean, the ocean data acquired by the various sensors on board need to be processed and quality controlled systematically. In this paper, we use the underwater glider "Sea-wing" developed by Shenyang Institute of Automation of Chinese Academy of Sciences to process the temperature and conductivity data, and use the quality-controlled underwater glider data to analyze the mesoscale eddy data in the South China Sea, and combine other observations and model data to analyze the mesoscale eddy structure and evolution of the northern part of the South China Sea.

This paper first investigates the processing of temperature and conductivity observations obtained by the underwater glider. The thermal lag effect caused by the underwater glider is re-evaluated, and the conventional correction methods show that there are over-correction and under-correction for the thermal lag correction of large temperature difference and low sampling frequency. This paper presents an optimized segmentation correction algorithm based on Morison's algorithm and the ocean physical environment field, which improves the salinity profile bias for large temperature difference and low sampling. After applying the optimized algorithm to all profiles, the typical salinity correction ratio is improved from 1.56 to 2.04, and the salinity difference between the downside and upside profiles is reduced from 0.011 to 0.006. This paper presents the real-time quality control process for the "Sea-Wing" underwater glider, including time check, continuity check, grammar check, spike check, gradient check, temperature and salt curve check, etc. After checking the above quality levels and post-processing the data, the marked data are output in scientific format with different processing levels and displayed in visualization software.

Then this paper evaluates the depth-averaged flow based on the temperature and salt field obtained by the "Sea-Wing" underwater glider and the satellite positioning data, and estimates the depth-averaged flow error to be about 0.036 m/s according to the shipboard ADCP error analysis method. This paper also analyzes another vertical temperature and salt profile of anticyclonic eddies in the northern South China Sea. The influence depth of the cyclonic eddies reaches about 1000 m, and the maximum temperature anomaly of the eddies is at 120 m; the temperature anomaly is smaller above 50 m, and the maximum salinity anomaly of the eddies appears in the mixed layer.

Finally, this paper analyzes the evolution of a cyclonic eddy near Xisha Islands in the northern part of the South China Sea by combining underwater glider data processing and current measurement methods. A cyclonic eddy was distinguished by data revision as well as probability density statistical analysis, and showed an inhomogeneous temperature structure and high salinity values (>34.7). The amplitude and radius of the eddy continued to increase during its growth phase, gradually weakened after crossing the Xisha Islands, and dissipated rapidly in western Vietnam. The VDI (vorticity and deformation index) and OW(Okubo-Weiss) parameters combined with the satellite altimeter data indicate that the eddy was still composed of a large number of vortices after reaching the Xisha Islands. The horizontal distribution of BC (baroclinic)and BT (barotropic)indicates that the eddy gains energy from the barotropic and baroclinic instability during the eddy generation phase; during the dissipation phase, BT and BC were negative in the northern part of the cold eddy, where the bottom drag enhances the mean horizontal velocity shear and thus suppresses the growth of lateral velocity disturbance; BT was positive in the southern and eastern parts of the cold eddy. The positive values of BT in the southern and eastern parts of the cold eddy and BC in the eastern part of the cold eddy indicated the instability and eddy generation due to the topographic features, and further analysis shows that the wind stress curl was not the cause of eddy dissipation after the eddy reaches the Xisha Islands. The correlation between VDI and BT and BC were found that the VDI index can indicate the eddy growth in the eddy growth phase; in the eddy dissipation phase, the VDI index is not significantly correlated with BC and BT.

Subject Area物理海洋学
MOST Discipline Catalogue理学::海洋科学
Pages108
Funding ProjectNational Key R&D Program of China[2016YFC0301203] ; National Natural Science Foundation of China[41576060]
Language中文
Table of Contents

目 录

目 录. I

第一章 绪论. 

1.1 引言. 

1.2 研究背景. 

1.2.1 国外水下滑翔机发展背景... 

1.2.2 国内水下滑翔机发展现状... 

1.3 研究现状. 

1.3.1 水下滑翔机数据处理研究现状... 

1.3.2 中尺度涡旋观测研究现状... 

1.4 研究目的及意义. 

1.5 本文主要研究内容. 

第二章 高密度水下滑翔机温盐观测数据处理. 

2.1 引言. 

2.2 传感器响应时间修正. 

2.3 热滞后效应修正. 

2.3.1 热滞后效应介绍... 

2.3.2 Morison热滞后效应修正... 

2.3.3 盐度和温度误差... 

2.3.4 分段修正与常规修正... 

2.3.5 分段热滞后修正... 

2.4 水下滑翔机温盐质量控制. 

2.4.1 质量测试标识符... 

2.4.2 实时温盐数据质量测试... 

2.4.3 数据后处理... 

2.5 数据文件处理等级. 

2.6 水下滑翔机数据可视化. 

2.7 本章小结与讨论. 

第三章 中尺度涡观测及测流海洋应用分析. 

3.1 引言. 

3.2 水下滑翔机测流计算方法. 

3.2.1 深度平均流... 

3.2.2 绝对地转流... 

3.3 深度平均流评估. 

3.4 绝对地转流. 

3.5 南海中尺度涡旋观测特征分析. 

3.6 本章小结. 

第四章 基于水下滑翔机观测的南海中尺度涡物理结构及能量分析. 

4.1 引言. 

4.2 南海中尺度涡简介. 

4.3 研究资料和方法. 

4.3.1 水下滑翔机观测资料... 

4.3.2 卫星高度计数据... 

4.3.3 中尺度涡追踪识别方法... 

4.3.4 高精度模式数据... 

4.3.5 研究方法... 

4.4 水下滑翔机观测中尺度涡. 

4.5 卫星高度计追踪和识别涡演化. 

4.6 涡形变与能量分析. 

4.6.1 高精度海洋模式数据验证... 

4.6.2 三维涡旋结构... 

4.6.3 涡旋生成和演化机制分析... 

4.7 本章小结与讨论. 

第五章 全文总结与展望. 

5.1 总结. 

5.2 创新点. 

5.3 展望未来. 

参考文献. 

致 谢. 

作者简历及攻读学位期间发表的学术论文与研究成果. 

Document Type学位论文
Identifierhttp://ir.qdio.ac.cn/handle/337002/179696
Collection海洋环流与波动重点实验室
Recommended Citation
GB/T 7714
褚福硕. 水下滑翔机观测数据处理及南海北部中尺度涡演变过程个例研究[D]. 中国科学院海洋研究所. 中国科学院大学,2022.
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