西北太平洋环流及其对我国近海环流的影响

【作者】 许东峰；

【导师】 袁耀初；

【作者基本信息】 中国科学院海洋研究所 ， 海洋科学，物理海洋专业， 2000， 博士

【摘要】 本论文介绍了MOM2.0模式的差分格式以及开边界情形的改进，较好地模拟了西北太平洋环流的季节变化和黄海冷水团环流结构。 第三章计算了北太平洋环流的季节变化，模式先从年平均温盐场开始积分，积分8a后基本上达到动力平衡态，再以月平均海表面条件积分4a后达到季节平衡态。结果表明：1）PN断面黑潮流量冬季为29.0×10~6m~3/s（SV），夏季为32.2×10~6m~3/s（SV），这与Sverdrup关系相反，这主要是由于风应力涡度零线随季节变化而导致北赤道流在菲律宾以东的分叉线春夏季偏南而秋冬季偏北。2）由于层化影响，东海黑潮夏季较冬季表层流速明显地强化。3）在台湾以东，黑潮明显地分为黑潮主流与东分支，主流穿过苏澳海脊进入东海，然后经吐噶喇海峡进入日本以南海域，东分支则流向琉球群岛以东海域，然后也进入日本以南海域与前一个分支相汇合。4）与网格相关的Smagorinsky方案要比采用常数更能反映中尺度结构。 第四章采用1997年7月的水文资料，计算了西北太平洋21.875°N～35.125°N、120.875°E～137.125°E范围的环流，主要结果如下：在此期间，1）黑潮在台湾以东并不存在东分支流向琉球群岛以东海域；2）东海黑潮的流量约为30×10~6m~3/s（SV），日本以南黑潮流量最大约为70×10~6m~3/s（SV）；3）在21.875°N～25°N之间大约有15×10~6m~3/s（SV）的流量向西流去。速度分布与流函数分布均表明这一支向西的海流大约在冲绳岛西南分为3支，主要分支转向东北沿冲绳岛以东海域向东北流去；4）琉球海流主要来自上述西向海流。 第五章通过理论分析及数值模拟研究了底边界混合和地形热累积效应对黄海夏季斜压结构的影响。黄海的垂向混合系数为10～100cm~2/s。结果表明：1）不同强度的潮混合，导致黄海冷水团的温度分布完全不同，较强的潮混合造成了海底附近直立型温度分布。黄海的热传导特征时间尺度为几天。2）黄海冷水团的水平环流 9在垂直方向上分为两层，上层为气旋式环流，其流速较强而厚度较厚，下层为反气旋式环流，流速较弱而厚度较簿（约10。20m人 二者的相对强弱与底边界混合的强弱关系不大。垂向积分环流则为气旋式的。3）黄海冷水团环流受温度分布影响，而后者受环流的平流效应的影响则较小。 论文的主要创新有三点： 1．发现 PN断面黑潮流量的夏季略强于冬季的原因主要是因 为风应力涡度零线随季节变化而导致北赤道流在菲律宾以东的 分叉线春夏季偏南而秋冬季偏北。从动力学上阐述了PN断面 黑潮流量季节变化的机制。 2．在 1997年 7月黑潮在台湾以东并不存在东分支流向琉球 ＋ 群岛以东海域：在21．875“＊～25“N之间大约有15x10＿Vs 的流量向西流去。速度分布与流函数分布均表明这一支向西的 海流大约在冲绳岛西南分为3支，主要分支转向东北沿冲绳岛 以东海域向东北流去：琉球海流在此期间主要来自上述西向海 流。 3．不同强度的潮混合，导致黄海冷水团的温度分布完全不 同，较强的潮混髓成了海底附近直立型温度分布。黄海的热 传导特征时间尺度为几天：黄海冷水团的水平环流在垂直方向 上分为两层，上层为气旋式环流，其流速较强而厚度较厚，下， 层为反气旋式环流，流速较弱而厚度较薄哟 10～20m），二者 的相对强弱与底边界混合的强弱关系不大。垂向积分环流则为 气旋式的。黄海冷水团环流受温度分布影响，而后者受环流的 平流效应的影响则较小。更多还原

【Abstract】 The seasonal change of the circulation of Northwest Pacific and the circulation structure of Yellow Sea Cold Water Mass (YSCWS) in summer are studied with Modular Ocean Model (MOM2.O). In Chapter three the seasonal change of the circulation of Northwest Pacific is investigated. The annual forcing are used to integrate the model till 8 years. After that, monthly forcing are used to integrate the model for another 4 years when the seasonal equilibrium has reached for the upper layers. The model results show that: 1) The Volume Transport (VT) of Kuroshio changes in the East China Sea from 29.0 X 106m3/s in winter to 32.2 X I 06m3/s in summer, which is in contrast with the Sverdrup relation. One of the main cause of the seasonal change of VT of Kuroshio in the East China Sea is that there is seasonal changes of position of the zero-line of curl ~ (~ is the wind stress), which then cause the seasonal shift the bifurcation position of North Equator Current in the Phillippine Coast. 2) The comparison between the surface velocity in the East China Sea in summer and winter shows the intensification of the former, which is in consistence with the observation. 3) The Kuroshio east of Taiwan bifiircates into two branches: the main stream and eastern branch. The main stream flows northward into the East China Sea, and the eastern branch flows northeastward to the region east of Okinawa Islands. 4) The Smagorinsky scheme is capable to simulate the mesoscale phenomena. In Chapter four, based on the CTD data during July of 1997 from the cruise of China-Japan Cooperative Study on the Subtropical Circulation and the data of the same period of Global Temperature Salinity Profile Program (GTSPP) Real-time Data Sets, MOM2.0 is used to calculate the circulation for the 5 region of 21.8750 N~-?5.1250 N,120.8750 E~?37.1250 E. Both Diagnostic and Robust Diagnostic simulations are done. The result of Diagnostic simulations is more reliable. The main feature of the circulation 7 pattern in this season is as below: 1) The Kuroshio east of Taiwan does not split into two branches as usual. 2)The VT of Kurosbio in the East China Sea is about 30X 106m3/s. The VT south of Japan is about 70X 106m3/s. 3) There is a westward flow at 21.875 N~-?50 N comes from 137~ E with a VT of 15 X 1 06m3/s(SV). It splits into three branches south of Okinawa Islands, the main branch flows northeastward east of Ry黭y?guntO. 4) The Ry黭y? Current comes mainly from the above westward flow. In Chapter five theoretic solution of one dimensional heat transfer equation and a numerical simulation of 3D baroclinic circulation by MOM2.O are found to analyze the influence of bottom boundary mixing and the Topographic Heat Accumulation Effect (THAE) to the baroclinic structure of the YSCWS in summer. The vertical eddy viscosity of Yellow Sea is about 10條OOcm2/s. Our results show: 1) for different tidal mixing, the YSCWS shows different temperature distribution. Strong bottom boundary mixing makes the doming thermocline. The time scale of heat transfer is about a few days, while the circulation response in a longer time scale. 2) The circulation of YSCWS has a two4ayer structure. The circulation in the upper layer is cyclonic, while it is anticyclonic in the lower layer, and is thinner (about 10?0 meter) and weaker than the upper layer. The vertical integrated circulation is cyclonic. The strength of the bo更多还原