基于四维变分同化方法的南海中尺度涡后报实验     

赵军  高山  王凡 《海洋与湖沼》2021,52(5):1145-1159

海洋中尺度涡在本质上是属于满足准地转平衡的大尺度运动,因此理论上,其在短时间内的运动将主要受到准地转平衡关系的约束,而外部强迫场的影响在短期内不会明显改变其运动特征。基于上述思想,我们提出了一种基于四维变分同化初始场的中尺度涡旋预报方案。为了检验该方案的可行性,本文使用区域海洋模式(regional ocean modeling system, ROMS)和其内建的增量强约束四维变分同化(incremental strong constraint four dimensional variational, I4D-Var)模块,建立了一个南海海洋同化模拟系统。首先,通过I4D-Var方法将AVISO卫星高度计资料同化到海洋数值模拟中,获得了理想的中尺度涡同化模拟结果。同化、模式模拟和观测三者的中尺度涡统计结果表明,该同化系统模拟的南海中尺度涡的路径、半径、海表高度异常和振幅等特征信息与AVISO(Archiving ValidationandInterpolationofSatelliteOceanographicData)观测结果高度吻合,同时在深度上的分析表明,涡旋对应的温度、盐度和密度均得到有效的调整。然后,将该同化系统的模拟结果做为初始场,对某一特定时段的南海中尺度涡进行了后报模拟和结果的定量化分析。通过比较后报模拟与观测资料中对应涡旋的海表面高度异常(sea surface height anomalies, SSHA)相关系数、涡心差距和半径绝对误差,证明该方案的中尺度涡后报时效至少可达10 d以上。后报实验结果验证了该中尺度涡预报方案的可行性,从而为中尺度涡的预报提供一定的理论基础和可行性方案。  相似文献   

Eddies in the northwest subtropical pacific and their possible effects on the South China Sea   总被引：1，自引：0，他引：1  

LIU Qinyu Daniel Souza JIA Yinglai LIU Wei 《中国海洋大学学报(英文版)》2005,4(4):329-333

Based on an analysis of drifter data from the World Ocean Circulation Experiment during 1979-1998, the sizes of the eddies in the North subtropical Pacific are determined from the radii of curvature of the drifter paths calculated by using a non-linear curve fitting method. To support the drifter data results, Sea Surface Height from the TOPEX/POSEIDON and ERS2 satellite data are analyzed in connection with the drifter paths. It is found that the eddies in the North Pacific （18^＊- 23^＊N and 125^＊-150^＊E） move westward at an average speed of approximately 0.098 ms^-1 and their average radius is 176 km, with radii ranging from 98 km to 298 km. During the nineteen-year period, only 4 out of approximately 200 drifters （2%） actually entered the South China Sea from the area adjacent to the Luzon Strait （18^＊-22^＊N and 121^＊-125^＊E） in the winter. It is also found that eddies from the interior of the North Pacific are unlikely to enter the South China Sea through the Luzon Strait.  相似文献   

Numerical study on the summer circulation of the upper South China Sea and its establishment     

CAI Shuqun  SU Jilan  LONG Xiaomin  WANG Shengan  HUANG Qizhou 《海洋学报(英文版)》2005,24(1):31-38

A coupled single-layer/two-layer model is employed to study the South China Sea (SCS) upper circulation and its response before and after the onset of summer monsoon. It is found that, in summer, due to the β effect and the first baroclinic mode of the wind-driven current, a northward western boundary jet current is formed along the Indo-China Peninsula coast, and it leaves the coast at about 13° N and diffuses towards northeast; next to the Indo-China Peninsula, a large anticyclonic  相似文献   

Taiwan Current (Kuroshio) and Impinging Eddies   总被引：16，自引：1，他引：15  

Yih Yang  Cho-Teng Liu  Jian-Hwa Hu  Momoki Koga 《Journal of Oceanography》1999,55(5):609-617

Considerable westward or nothwestward propagating eddies were found east of Taiwan that cross-explains the anomalies in the repeated hydrography, trajectory of drifting buoys and altimetric analyses. The sea level differences (SLD) across the Taiwan Current (Kuroshio) in the East Taiwan Channel (ETC) are utilized in order to examine the possible implication of eddies in the Taiwan Current transport. It is concluded that Taiwan is impinged by both cyclonic and anticyclonic mesoscale eddies at an interval of about 100 days. An approaching anticyclonic eddy will result in a higher SLD across the ETC and a larger mass transport of Taiwan Current, and, vice versa, a reduction of both SLD and the mass transport in the ETC as a cyclonic eddy arrives. The SLD-inferred northward transport in the ETC is highly coherent at the 100-day band with westward propagating eddies that originated in the interior ocean. The generation mechanism of these eddies are, however, still unclear. Leakage of the Kuroshio water to the east of the Ryukyu Islands is suggested due to the presence of cyclonic eddies. This 100-day rate of eddy-impingement invalidates any observation of 4 months or less, whether with direct or indirect measurements, because any conclusions depend on the presence or absence of eddies. To minimize the contamination from eddies, either long-term observations or eddy-removal procedures are required.  相似文献   

对末次间冰期南黄海古冷水团沉积的探讨   总被引：5，自引：1，他引：4  

杨子赓  林和茂 《海洋地质与第四纪地质》1998,18(1):47-58,T001

末次间冰期高海面时期,在南黄海ＱＣ２孔发现了介形类化群中“环北 极种”为其优势种,组合中数量最多的是Ｓａｒｓｉｃｙｔｈｅｒｉｄｅａｂｒａｄｉｉ,其中现代分布范围在我国浅海区十分狭窄,集中在北黄海冷水团控制区,冷水种在整个间冰期化石组合中占７９％以上;有孔虫组合在７０％以上的沉积层段中其优势种和主要成分以不种和喜中为主,如Ｂｕｃｃｅｅｌｌａｆｒｉｇｉｄａ,Ｐｒｏｔｅｌｈｉｄｉｕｍｔｇｕｍｔｕｂｅｒｃ  相似文献   

Wind-driven South China Sea deep basin warm-core/cool-core eddies   总被引：8，自引：0，他引：8  

Peter C. Chi  Yuchun Chen  Shihua Lu 《Journal of Oceanography》1998,54(4):347-360

The formation of the South China Sea (SCS) deep basin warm-core and cool-core eddies was studied numerically using the Princeton Ocean Model (POM) with 20 km horizontal resolution and 23 sigma levels conforming to a realistic bottom topography. Numerical integration was divided into pre-experimental and experimental stages. During the pre-experimental stage, we integrated the POM model for three years from zero velocity and April temperature and salinity climatological fields with climatological monthly mean wind stresses, restoring type surface salt and heat fluxes, and observational oceanic inflow/outflow at the open boundaries. During the experimental stage, we integrated the POM model for another 16 months under three different conditions: one control and two sensitivity runs (no-wind and no lateral transport). We take the fields of the last 12 months for analysis. The simulation under control run agrees well with earlier observational studies on the South China Sea surface thermal variabilities. In addition, the sensitivity study further confirms that the wind effect is the key factor for generation of the SCS deep basin warm/cool eddy and that the lateral boundary forcing is the major factor for the formation of the strong western boundary currents, especially along the southeast Chinese coast during both summer and winter monsoon seasons.  相似文献   

南海东北部及台湾海峡附近环流的一个耦合模式Ⅱ.模式的试验结果     

蔡树群  黄企洲  麦波强 《热带海洋学报》1998,(4)

利用一个耦合的数值模式对南海东北部及台湾海峡附近的环流进行数值模拟,以研究多种可能的动力机制对该海区的影响。结果表明：当以风应力、黑潮作为驱动机制时,该模式的计算结果大致与正压模式的计算结果相同;风应力促使研究海区流场的结构和强度发生变化,而黑潮才可能是该海区动力机制的主要因子。黑潮人流、入射角及海区层结程度等因素对该海区流态变化的影响较大;文章同时指出摩擦效应对于流场结构产生影响的重要性。  相似文献   

吕宋海峡海洋环流的基本特征   总被引：7，自引：2，他引：5  

李薇  刘秦玉  杨海军 《中国海洋大学学报(自然科学版)》1998,(3)

根据对高分辨率的并行海洋气候模式输出的较长时间序列的海面高度（ＳＳＨ）场的分析,推断在吕宋海峡附近海区常年存在吕宋海峡黑潮流套,该流套出现于吕宋海峡的中部和北部,表现为一个舌状的ＳＳＨ的高值中心自海峡东部的太平洋向西扩展到南海北部,大致到达１１０°Ｅ的位置,但其位置、形状、强度等表现季节变化,年际变化和季节内时间尺度变化的特征。在吕宋海峡东侧的大洋上,经常出现位置和范围时有变化的反气旋涡,与之对应,在ＳＳＨ的月平均经向和纬向剖面上,吕宋海峡东侧的大洋上有永久存在的ＳＳＨ高值中心。另外在１９９５年１～７月期间有一次完整的黑潮流环脱离黑潮主体并在南海北部向西南方向移动的过程。  相似文献   

地形和风速影响下的海气相互作用大涡模拟研究     

叶灿  成泽毅  高宇  宋金宝  李爽 《海洋与湖沼》2023,54(6):1537-1550

当水流经过海洋地形时,水流的不稳定性会引起垂向混合并伴随大量湍流过程。针对传统海气耦合模式缺少在湍流尺度上讨论海洋地形与风速对海气相互作用影响的问题,使用并行大涡模拟海气耦合模式(the parallelized large eddy simulation model, PALM)在5 m/s的背景风场下,引入理想立方体地形,对比有无地形的影响;设置地形边长为L,高为3L (其中大气部分高L), L与水深H之比为L/H=1/2;然后保持地形条件不变。设置5、10和15 m/s三种风速,讨论风速对小尺度海气相互作用的影响。研究表明:地形在大气部分减弱顺风向速度,增强侧风向速度,影响0～5L的高度区域,而对垂向作用较小;无地形条件下湍流垂向涡黏系数K_m在-0.3L时,水深达到最大值0.024 m²/s,有地形条件下K_m在-0.8L时,达到最大值为0.16 m²/s,地形的存在使得上层海洋混合加强, K_m最大值增加1个数量级。随风速增大海洋和大气中的净热通量、淡水通量和浮力通量都相应...  相似文献   

基于水下滑翔机观测数据的西北太平洋混合层特征研究          下载免费PDF全文

杨得厚  郑建华  靖春生  郭绍敬  黄奖  杨华勇 《应用海洋学学报》2023,42(1):100-109

基于水下滑翔机在2019年8至10月观测到的温盐资料,本研究分析了西北太平洋混合层总体的变化情况,并探讨了混合层异常变化的原因。结果表明,混合层温度总体上呈现随季节转换逐渐降低的趋势,混合层深度总体上呈现随季节转换逐渐增大的趋势。进一步的相关性分析得出,该海域混合层温度、混合层深度的变化特征主要是由外部大气强迫场（海面风场和净热通量）所决定的。水下滑翔机还观测到了混合层温度异常降低、混合层深度异常变浅的现象。通过计算混合层热收支发现,垂向夹卷作用是海洋混合层内温度降低和混合层深度变浅的主要原因。通过进一步计算研究海域冷涡的上升速度与海水垂向夹卷速度的变化情况,并结合卫星遥感资料,得出海洋的中尺度涡旋活动主导了混合层异常现象的发生。  相似文献