南海西北部陆架海域内孤立波特征及机理研究

IOCAS-IR > 海洋环流与波动重点实验室

	南海西北部陆架海域内孤立波特征及机理研究
其他题名	Characteristics and Mechanisms of the Internal Solitary Waves over Northwestern South China Sea Shelf
	徐振华
学位类型	博士
	2009-05-25
学位授予单位	中国科学院海洋研究所
学位授予地点	海洋研究所
关键词	内孤立波上凸型第二模态陆架局地产生南海
摘要	关于南海北部内孤立波的研究，现在是一个国际性研究热点，以往对南海北部海域的内孤立波的研究大都集中于南海东北部，即东沙-吕宋海峡海域。对于南海西北部文昌海域的内波现场调查研究几乎是空白。2005年4-10月中科院海洋所对南海西北部陆架海域进行了现场内波观测，获得了到目前为止国内连续观测时间最长、高分辨率、高质量的温度及流场数据。本文使用此次观测所获得的海流和温度资料，主要针对观测海域内孤立波特征及机理进行分析研究，取得了若干有重要科学意义的成果,主要为: 该海域是内孤立波多发地区，其中从2005年4月中旬到6月孤立波频繁出现且振幅较大，而6月中旬到9月中旬，内孤立波的发生频率明显下降，振幅也相对较小; 内孤立波的极性也表现出明显的季节性变化特征。研究发现内孤立波的季节性变化特征是与跃层的深浅和强弱密切相关的。在2005年9月期间观测到了一系列的大振幅内孤立波，其中在同一测站的不同天内分别发现上凸型和下凹型内孤立波。研究表明这些内孤立波极有可能是由陆架坡折处的内潮因非线性和频散效应而局地产生的。这是首次通过现场观测确认南海西北部存在上凸型并且其为局地生成的内孤立波。进一步分析发现在2005年8月21-23日，观测到了第二模态的内孤立波，这些内孤立波是与第二模态的内潮同步发生的，在连续两天内几乎相同的时刻分别观测到第二模态的内孤立波说明这些孤立波是潮致的。在2005年4月22-28日发现长时间的强海流现象，强海流现象发生在当地的天文潮小潮期间，沿岸方向的流速明显大于垂直于岸方向的流速，通过分析表明强海流是由当地的内潮流引起的。根据观测的温、流数据分析了内波场对台风的响应过程及内波谱特征，发现台风对观测站位的温度场和流场结构均有显著的影响。这些在南海西北部的新发现和新认识对推动内孤立波的产生机制和应用技术的研究具有重要的学术价值。
其他摘要	The study of internal solitary waves (ISWs) has become an international hotspot in the northern South China Sea (SCS). Most study of ISWs has been focused on northeastern SCS, while there has been few or no field study of ISWs over northwestern SCS. Field observations were made from April to October 2005 at Wenchang Station on the northwestern shelf of SCS by Institute of Oceanology, Chinese Academic of Science. A complete set of current and temperature data of mooring measurements has been acquired to investigate the characteristics and mechanism of internal solitary waves. Some important scientific achievement has been acquired and summarized as followed: Internal solitary waves were active in this area. ISWs with large amplitude appeared frequently from April to June while less internal solitary waves occurred from July to September and their amplitude was smaller than that from April to June. The polarity of ISWs also displayed apparent seasonal features. The seasonality of ISWs is closely related to the depth and strength of the thermocline. A sequence of large internal solitary wave packets was observed in September 2005, propagating mainly northwest. Both elevation and depression ISWs were observed at the same mooring location in different days during this period. Results indicated that they were probably generated locally from the shelf break by the evolution of the internal tides due to nonlinear and dispersive effects. To our knowledge, this is the first report to confirm the locally generation mechanism of the ISWs based on in-situ measurements in the northwestern South China Sea. We also found mode-2 internal solitary waves accompanied by the mode-2 internal tides during our experiment. Two mode-2 internal solitary waves occurring roughly during the same time in consecutive days suggests that tides are the origin of the waves. Long-time strong current phenomenon was recorded from 22 April to 28 April. This period is during the ebb tides of the mooring site. The current mainly moved along the coastline. The analysis suggests that the strong currents are induced by the internal tide currents. Based on observed current and temperature data, the response of the internal wave to the typhoon and internal wave spectrum were analyzed. The temperature and current field were significantly affected by the typhoon. The new discoveries and knowledge of ISWs over the northwestern SCS have important scientific values for the study of the generation mechanism and technical application for the ISWs.
页数	112
语种	中文
文献类型	学位论文
条目标识符	http://ir.qdio.ac.cn/handle/337002/1485
专题	海洋环流与波动重点实验室
推荐引用方式 GB/T 7714	徐振华. 南海西北部陆架海域内孤立波特征及机理研究[D]. 海洋研究所. 中国科学院海洋研究所,2009.

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