IOCAS-IR  > 海洋环流与波动重点实验室
黄海暖流黄海冷水团及其春季演变过程研究
刁新源
Subtype博士
Thesis Advisor于非
2015-05-19
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline物理海洋学
Keyword黄海 黄海冷水团 黄海暖流 春季过程
Abstract黄海是连接渤海与外海的重要的陆架海域,该海域也是沿海经济、沿海养殖、海洋渔业、军事活动非常发达的海域,针对黄海典型海洋现象的研究有助于摸清黄海的水文背景特征,这对指导经济建设、渔业生产和提高军事活动安全性都是至关重要的。本文通过十几年来积累的大量的现场调查的温度、盐度和海流资料,开展对黄海典型海洋现象:黄海暖流和黄海冷水团以及春季转换过程的研究,力图揭示它们的基本特征和生成、发展、消亡的机制。
1. 春季黄海暖流存在的直接证据及其原因
冬季源自济州岛西南海域的黄海暖流水舌沿海槽西坡(大致70m等深线附近)从近底层北进,12月其前锋大约达到35°N,流轴处平均速度5-8cm/s,暖流抵达之处底层稳定升高约4°C。在34°N,122°E附近黄海暖流水舌分出一支指向青岛外海。冬季东北季风造成北部沿岸海域(包括渤海在内)失水,海水沿黄海西海岸南下,产生鲁北沿岸流和苏北沿岸流。其结果一方面在黄渤海区域建立了季节时间尺度海平面的南北高度差,形成了稳定的黄海暖流;另一方面寒潮的频繁爆发,造成了黄海暖流流速天气尺度的脉动。春季黄海暖流水前锋仍然可以达到37°N,并逐步失去来自济州岛西南海域高温高盐水的支持,暖流水舌根部出现明显降温(约2°C)、降盐(约1.0),而水舌前部降温、降盐较缓慢,暖流水舌逐步演变成几乎封闭的高温、高盐水块。另一方面,春季黄海暖流的天气时间尺度补偿作用消失,但冬季建立起来的北低南高的海平面,需要在春季得到恢复,因而黄海南部海水必须继续向北补偿,故此,驱使该高温高盐水块继续向北移动。在此过程中黄海暖流源区海水温度下降较明显,而盐度下降较缓慢;但它向北移动的过程,所到之处均出现升温升盐。黄海暖流水消亡的时间存在年际变化,大致在5月份到7月份完全消失;而指向青岛外海的黄海暖流的西北分支,因所处的空间尺度小,4月或4月之前其流和暖水舌已经消失,只留下盐度舌的痕迹。
2. 成山头东南海域中层冷水特性及其形成
春季在成山头东南海域50m等深度线附近出现中层冷水现象,冷水块在10-30m水层里,纬向尺度100km,其中心水温比周边低2°C、比表层低1.5°C、比底层低1.0°C。它是由黄海暖流水、沿岸冷水以及春季升温过程等诸因素在该海域相互作用的结果。首先是南下的成山头外海水带来低温、低盐的海水,这支海流在南下过程中与局地增温的表层海水和底层黄海暖流高盐水相遇,因为密度的原因插入两层海水之间,形成了低温、低盐的中层冷水。
3.黄海冷水团的形成过程
黄海冷水团主要是由冬季残留水形成的,但是其内部也存在弱的水交换。春季,成山头外海的冷水南下,其形成的中层冷水是青岛外海冷水团的主要组成部分,而青岛外海冷水团明显是黄海冷水团的一部分。夏季黄海冷水团存在两个较强的冷中心,一个是青岛外海冷水团,一个是仁川外海冷水团,中间黄海槽的位置则是黄海暖流的残留水。黄海暖流残留水在不同年份强度不一样,如果以底层相对高温、高盐定义黄海暖流残留水,它基本上出现在黄海槽西侧约70m等深线的附近。
4.黄海暖流和黄海冷水团环流的驱动机制
南北黄海存在明显的海表面高度差,冬半年青岛外海与北黄海水位低于南黄海,且初冬青岛外海失水比北黄海早,因此激发了底层黄海暖流的西北向分支,盛冬北黄海失水达到顶峰,因此黄海暖流逐渐转向北向;春季青岛外海与济州岛附近海域水位差快速消失,因此黄海暖流西北向分支快速退却完全转为北向,此时虽然南北黄海水位差趋于平衡,黄海槽西侧仍然存在弱的北向流,黄海沿岸流从成山头沿50m等深线南下,为青岛外海冷水团带来低温、低盐的海水,造成其核心温度的持续降低;夏季,黄海沿岸流持续存在,同时海槽中央西侧70m等深线附近存在弱的南向流,从北黄海带来低温、低盐的海水注入南黄海冷水团,造成了黄海暖流残留水的微弱降温、降盐。
Other AbstractThe Yellow Sea is an important continent shelf region connected Bohai Sea and open sea. The coastal economy, coastal culture, fishery, military activities in this region is very heavy, thus, the research focus on the typical marine phenomenon is very helpful to reveal the hydrological character, and is very important to guard the economy construction, fishery, and military activities safety. Through the temperature, salinity and current data collected in the recent decades, the study of the typical marine phenomenon was made to reveal the basic characteristics and the mechanism of the formation, development and extinction, which include the Yellow Sea warm current and Yellow Sea cold water mass and their transition in spring.
1. The direct evidence and cause of the Yellow Sea warm current in spring.
In winter time, the tough of the Yellow Sea warm current from the southwest region of the Cheju island flow northward along the west of the Yellow Sea trough. In November, the front of it reached 35 °N, and the average speed is 5-8cm/s in the axis. The temperature raised about 4°C in the bottom layer at the warm current path. At 34°N,122°E, one branch of the warm current tough is separated and flow to the Qingdao offshore. The winter monsoon cause the water loss in the coastal region in the north Yellow Sea (Bohai Sea included), then the water flow southward along the west coastal and force the Lubei coastal current and the Subei coastal current. Then, the seasonal altitude difference in Yellow Sea region was founded, and the stable Yellow Sea warm current was forced. In the other side, the weather time scale Yellow Sea warm current also exist to compensated the difference. In spring, the front of the Yellow Sea warm current still can reach 37 °N, but lose of the support of the high temperature and salinity Tsushima warm current in Cheju southwestern region, the temperature and salinity decreased clearly (about 2 °C and 1.0)in the root of the warm tough. At the same time, decrease is very slow in the front of the warm tough, then the warm tough turned into the almost closed high temperature and salinity water mass. Although the compensation function of the Yellow Sea warm current was disappeared, but the different in the SSH in winter need to recovery, thus the water in the south Yellow Sea should flow northward, then the high temperature and salinity water keep move to the north. In this progress, the temperature of Yellow Sea warm current decreased very clearly, while the salinity very slowly, but with movement to the north, the temperature and salinity raised in its path. There is an interannual variability in the distinction of the Yellow Sea warm current. And it will disappear within May to July. Because the space scale is very small, the northwest branch of the Yellow Sea warm current is disappeared before April, and only the high salinity tough was left.  
2. The characteristics and formation of the middle layer cold water in the southeast region of Shidao
The middle layer cold water appeared near the 50m isobaths at the southeast region of Shidao in spring. The cold water block exist between 10m and 30m layer, and it is 100km wide in the latitude direction. The temperature in center is 2 °C lower than the around, 1.5 °C lower than the surface, and 1.0 °C lower than the bottom. The formation of it is the interaction of the Yellow Sea warm current water, the coastal cold water and the temperature rising in the surface in spring. The low salinity cold water flows northward from the Chengshantou, and meet the warmer surface water and high salinity Yellow Sea warm current bottom water, because the density of them, the cold water insert the other two water, and form the low temperature and salinity middle layer water.
3. The formation of the Yellow Sea cold water mass in summer
The Yellow Sea cold water mass is mainly formed by the residual water in winter time, but weak water exchange happen inside. In spring, the cold water flow southward from Chenshantou, and become the middle layer cold water which is the main part of the Qindao cold water mass. According to the 10 °C isotherm, the Qingdao cold water mass is obviously the part of Yellow Sea cold water mass. In 36°N section, there are two low temperature center, which are in different place by years. The strength of the one near seashore is a little weak and the range is small too. There is no low salinity center in the same place. While the strength of the one in the west of Yellow Sea trough is strong and the range is big, correspondingly, there is a low salinity center in the same place. While in 35 °N section, there is only one low temperature center, and low salinity center appears correspondingly. There are two strong cold centers in the Yellow Sea cold water mass, one is the Qingdao cold water mass and the other is Inchon cold water mass. In the middle of the Yellow Sea cold water mass is the residual water of the Yellow Sea warm current water in winter. The strength of the residual Yellow Sea warm water is different in various years. If the high salinity center is the sign of the residual Yellow Sea warm water, it appears almost in the same place around the 70m isobaths in different years.
4. The driving mechanism of the Yellow Sea warm current and the Yellow Sea cold water mass.
The obvious differences of the sea level are exist between the southern Yellow Sea and the northern Yellow Sea. In winter time, the sea level in Qingdao is lower than it in the southern Yellow Sea, and this happened early than the sea level reduce in the northern Yellow Sea, thus the northwest branch of the Yellow Sea warm current was forced. In the midwinter, the water losing is the most in the northern Yellow Sea, then the Yellow Sea warm current turns to the northward. In spring, the difference of the sea level quickly disappeared between Qingdao and south Yellow Sea, thus the northwest branch of the Yellow Sea warm current requite and turns to the northward. Although the difference of sea level between the northern Yellow Sea and southern Yellow Sea is become little and little, the weak northward flow still exist in the west of the Yellow Sea trough. In summer, under the southern wind, the sea level of northern Yellow Sea is higher than southern Yellow Sea, and then the southward flow was forced. And the low salinity cold water is carried to the south Yellow Sea cold water mass from the northern Yellow sea, and finally the stable structure of the Yellow Sea cold water mass is formed.
Subject Area海洋环流与波动
Language中文
Document Type学位论文
Identifierhttp://ir.qdio.ac.cn/handle/337002/23279
Collection海洋环流与波动重点实验室
Affiliation中国科学院海洋研究所
First Author AffilicationInstitute of Oceanology, Chinese Academy of Sciences
Recommended Citation
GB/T 7714
刁新源. 黄海暖流黄海冷水团及其春季演变过程研究[D]. 北京. 中国科学院大学,2015.
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