【作者】 白志鹏；

【导师】 鲍献文；

【作者基本信息】 中国海洋大学 ， 流体力学， 2007， 硕士

【摘要】 东中国海温、盐、流结构的长期变化与我国沿岸的气候、生态环境、海上作业等密切相关,认识此变化规律是保障我们进行海上资源开发、改善海洋环境质量的重要科学基础。而大洋中海洋要素的变化及异常信号的传播对我国近海也会产生一定影响。本文利用137°E断面和东海PN、TK断面多年温度、盐度资料,通过统计平均、动力计算、相关分析、线性回归分析、谱分析等手段对断面和PN、TK断面的温度、盐度、地转流量及其长期变化规律进行了初步分析,还初步探讨了大洋中的异常变化对我国东海的影响,主要得出了以下结论:1. 137°E断面冬季28°C等温线北端的平均位置为,其变化的主周期为14年(与暖池表层水的年代际纬向运移的主周期[29]一致),而且以每年0.1个纬距的速度向北移动。2.在厄尔尼诺事件达到峰值前两个月,137°E断面低纬部分温跃层出现抬升运动,导致此区域次表层(100米)出现异常低温现象,而此区域下层300m到400m处(北赤道逆流区下侧)的温度变化与以上低温变化反相位,即在厄尔尼诺发生时该海域等温线倾斜加强,从而北赤道逆流加强,在拉尼娜发生时正好相反。而对于北赤道逆流区的温盐变化,东海PN、TK断面有两年的滞后响应(滞后相关系数分别为0.56和0.57)。oE3.当黑潮发生大弯曲时,137°E断面高纬度部分100米以下会出现大范围异常低温,100-700米的盐度表现为负异常,而700米以深的盐度会出现正异常,即与上层盐度变化反相位。主要是由于黑潮大弯曲时在日本伊豆诸岛西侧伴随生成逆时针涡旋造成深层水的上涌所致。盐度的反相位变化是由于断面盐度的气候分布特征为中层低、上层和底层相对高,所以当水柱上涌时原本的高盐水被低盐水代替,而原本的低盐水被高盐水代替。另外上层海洋盐度有上升趋势,下层海洋盐度有减小趋势,但整体平均的盐度几乎保持不变。4. 137°E断面上次表层高盐度水的强度(中纬区盐度高于35.0的区域面积)和中层低盐水的强度(400米以深盐度低于34.2的区域面积)都有较大的年际变化,次表层高盐水长期变化趋势不明显,而中层低盐水有逐年增强的趋势。5.黑潮大弯曲导致的断面高纬部分低温和低盐(700以浅)现象与PN、TK断面的温盐变化相关性不大,而250米以浅的区域,以上三个断面温度、盐度有显著相关性(0.70以上),表明这三个断面上层的温、盐变化主要由流经它们的黑潮所联系。6.黑潮发生大弯曲时, PN断面的流量增大,断面的黑潮流量减小,主要是因为黑潮发生弯曲时在日本以南黑潮的两侧会出现中尺度环流,这些中尺度涡消耗了一部分黑潮主干的流量。黑潮不弯曲时两断面的流量变化大体一致。PN断面的流量增大对东海有增温的作用,而厄尔尼诺现象对我国东海有降温作用[62],最终结果由二者共同作用确定,其中一个总会对另一个的效果产生抑制作用。更多还原

【Abstract】 The long-term structural changes of temperature, salinity, and current at East China Sea are closely related to the coastal climate, ecological environment, and sea operations of China. Knowing these changes is the scientific basis to safeguard our offshore development activities, environmental quality, and biological sources. And changes of the marine elements in oceans and of the spread of the abnormal signal would also have a certain impact on our coastal waters.In this paper, data along the 137°E and PN,TK section gathered during 1967-2003 were used to study the interannual variability in the northern ECS, through statistical methods such as, linear fit analysis,correlation analysis, dynamic height calculation and wavelet spectrum analysis.The conclusions were drawn as follows:1 Northern mean position of 28°C isotherm along the 137°E section is 8.9°N in winter,it varies with a period of 14 years( This is consistent with the period[29] of the zonal movement of surface warm water in the western Pacific warm pool),and it moved northward with a speed of 10km/a.2 Temperature on the south of the 137°E section is ralated with the vertical displacement of thermocline accompanied by El Nino and La Nina events. In this area at depth of 300m to 400m (NECC range) has negative correlations with this variation so that it strengthens the current of the NECC during El Nino events and weakens it during La Nina events. Temperature and salinity of PN and TK section respond with the variation of NECC range 2 years later.Their correlative coefficient is 0.56 and 0.57.3 When the meander of Kuroshio occurs ,there will be large-scale low-temperature and low salinity anomalies at 100 meters deeper area on the norhern of the 137°E section. However, there is positive anomaly of salinity at 700 meter deeper area, i.e. the salinity changes of this area is anti-phase to that of upper area. It is mainly due to the influence of the large cold water in the west side of Japan Izu islands generated by the meander of Kuroshio. The distribution of salinity in this section relatively low at the middle, and relatively high at the upper and the bottom layers. Therefore, when the water column upwelling happens, the original high salinity water is replaced by low salinity water, while the original low salinity water is replaced by high salinity water, which causes the anti-phase changes above. Moreover, there is an upward trend of upper ocean salinity, whereas a downward trend of lower ocean salinity, nevertheless, the overall salinity remains almost unchanged.4 Distributing of intermediate water and sub-surface saline water has big differences from year to year .Intensity of intermediate water trends bigger,and the sub-surface saline water trends calmly.5 Meander of Kuroshio result in the descension of temperature at the 137°E section.This descension correlates with PN、TK section hardly.But temperature and salinity of these three sections varies in-phase upper 250m layer.So variation of temperature and salinity at these three sections associates by current——Kuroshio. 6 When meander of Kuroshio occurs,the flux of PN section will increase. the nothern of 137°E section varies with negative correlations. if meander of Kuroshio doesn’t occurs ,flux of PN section varies consistently with the 137°E’s.The increasing of flux over PN section is associate with positive temperature anomaly, however negative temperature anomaly is associated with El Nino[62].Temperature is decided by their intensity,the weaker one prevent the effects of the other.更多还原