海洋切变波成长及发展的一个模式

本文从准地转涡度方程出发利用伪谱方法对存在于大洋西边界流强剪切区中的切变波的形成过程进行了直接数值模拟。据K-H不稳定性理论,适当选取的初始扰动从平均运动中吸取能量而迅速成长。得到的等涡线的变化反映了涡对通过合并或撕裂方式成长为大涡的过程,而物质线的演化过程形象地再现了暖水回流和冷水入侵所形成的倒卷结构,与卫星照片显示的结果非常相似。非线性作用使能量在不同尺度的运动间相互传输,值得注意的是,随着扰动振幅的增大能量将从扰动运动返回平均运动,这相当于雷诺应力为负值。     

全球气候变化对海洋声吸收系数的影响研究

基于地球系统模式FIO-ESM(The First Institute of Oceanography-Earth System Model),研究了在最高排放RCP8.5情景下1851—2100年海水温度、盐度和酸度的变化规律,综合考虑三者得到了声吸收系数的变化规律。FIO-ESM模式输出结果表明,1851—2100年间大部分区域的海水温度出现不同程度地上升,海洋酸化现象明显,北极地区附近的海水盐度出现较大程度的下降。利用Francaais-Garriso经验公式计算海洋声吸收系数发现,如果只考虑酸度对声吸收系数的影响,声吸收系数的预报误差将达到40%以上。综合计算结果表明,随着全球气候变化的演进,全球海洋声吸收系数出现不同程度的下降,最大可达70%,即未来的海洋对于声波更加"透明"。     

地球系统模式FIO-ESM v2.0对北太平洋年代际气候变化的模拟评估

数值模拟方法在研究长时间的气候变化上扮演着重要角色。一直以来,数值模式模拟年代际气候变化如太平洋年代际震荡（PDO）的位相转换存在巨大挑战。本文利用自然资源部第一海洋研究所研发的地球系统模式（First Institute of Oceanography-Earth System Model Version 2,FIO-ESM v2.0）145年（1870–2014年）历史气候模拟试验结果,结合再分析资料和另外两个地球系统模式结果,分析评估了该模式对太平洋年代际振荡的模拟能力。研究发现,FIO-ESM v2.0能够再现历史时期PDO的空间模态分布特征,其PDO指数具有10～30年的周期变化特征,同时于1960年以后能刻画出与再分析数据结果相近的PDO位相转变特征。研究表明,FIO-ESM v2.0能够较为准确地模拟出PDO的位相转变特征。另外,本文还评估了该模式对大气环流模态的模拟能力及其与PDO之间的关系,以及该模式模拟PDO的可能机制。该模式的PDO与大气环流的阿留申低压模态相关。进一步的分析表明,平流作用和热通量是关键年代际海域海温异常振幅的主要因素,而罗斯贝波西传时间则可能是影响PDO位相转变的关键因素。     

辽东湾海蜇增殖放流模式的建立和应用

基于中国近海浪-流耦合业务化预报系统（OFS-C）和Lagrangian粒子追踪方法,本文首次建立了辽东湾海蜇增殖放流模型。模型中,海蜇用虚拟的粒子表示,具有昼夜垂直运动（DVM）特性。海蜇运动由海流和次网格参数化引起的随机运动驱动。利用航次调查数据对模型结果进行了验证,模式结果可以很好的模拟放流海蜇分布的主要结构。模型分析了物理过程对辽东湾放流海蜇的输运和分布的影响,结果显示海蜇运动主要受海流和间接的风应力的影响。放流地和捕捞地的连通性分析表明,辽东湾海蜇的主要捕捞地集中于湾顶。另外,连通性矩阵表明,瓦房店放流的部分海蜇不能到达捕捞地,因此,相对于其它放流地来说,瓦房店不是理想的放流地。敏感性实验表明了随机游走的重要性,但是对于游走格式并不敏感。海蜇栖息的深度会影响海蜇最终的分布,若海蜇栖息于海底,则在低层环流的影响下,最终分布于辽东湾中部,部分会流出辽东湾,而不能到达湾顶。     

基于CMIP5模式的南海海平面未来变化预估

Future potential sea level change in the South China Sea(SCS) is estimated by using 24 CMIP5 models under different representative concentration pathway(RCP) scenarios. By the end of the 21 st century(2081–2100 relative to 1986–2005), the multimodel ensemble mean dynamic sea level(DSL) is projected to rise 0.9, 1.6, and 1.1 cm under RCP2.6, RCP4.5, and RCP8.5 scenarios, respectively, resulting in a total sea level rise(SLR) of 40.9, 48.6, and 64.1 cm in the SCS. It indicates that the SCS will experience a substantial SLR over the 21 st century, and the rise is only marginal larger than the global mean SLR. During the same period, the steric sea level(SSL) rise is estimated to be 6.7, 10.0, and 15.3 cm under the three scenarios, respectively, which accounts only for 16%, 21% and 24% of the total SLR in this region. The changes of the SSL in the SCS are almost out of phase with those of the DSL for the three scenarios. The central deep basin has a slightly weak DSL rise, but a strong SSL rise during the 21 st century, compared with the north and southwest shelves.     

地球系统模式FIO-ESM对北极海冰的模拟和预估

评估了地球系统模式FIO-ESM(First Institute of Oceanography-Earth System Model)基于CMIP5(Coupled Model Intercomparison Project Phase 5)的历史实验对北极海冰的模拟能力,分析了该模式基于CMIP5未来情景实验在不同典型浓度路径(RCPs,Representative Concentration Pathways)下对北极海冰的预估情况。通过与卫星观测的海冰覆盖范围资料相比,该模式能够很好地模拟出多年平均海冰覆盖范围的季节变化特征,模拟的气候态月平均海冰覆盖范围均在卫星观测值±15%范围以内。FIO-ESM能够较好地模拟1979-2005年期间北极海冰的衰减趋势,模拟衰减速度为每年减少2.24×104 km2,但仍小于观测衰减速度(每年减少4.72×104 km2)。特别值得注意的是:不同于其他模式所预估的海冰一直衰减,FIO-ESM对21世纪北极海冰预估在不同情景下呈现不同的变化趋势,在RCP2.6和RCP4.5情景下,北极海冰总体呈增加趋势,在RCP6情景下,北极海冰基本维持不变,而在RCP8.5情景下,北极海冰呈现继续衰减趋势。     

台湾浅滩阻塞作用的初步研究

位于台湾岛西南横跨海峡的台湾浅滩处的水深不足20m(图1),它对于平均水深50m的台湾海峡中的流动有明显的阻塞作用.为了了解台湾暖流在浅滩附近的变化,我们有必要对浅滩阻塞的动力学机制进行深入研究.     

对地球系统模式FIO-ESM同化实验中北极海冰模拟的评估

本文评估了地球系统模式FIO-ESM(First Institute of Oceanography-Earth System Model)基于集合调整Kalman滤波同化实验对1992-2013年北极海冰的模拟能力。结果显示:尽管同化资料只包括了全球海表温度和全球海面高度异常两类数据,而并没有对海冰进行同化,但实验结果能很好地模拟出与观测相符的北极海冰基本态和长期变化趋势,卫星观测和FIO-ESM同化实验所得的北极海冰覆盖范围在1992-2013年间的线性变化趋势分别为-7.06×105和-6.44×105 km2/(10a),同化所得的逐月海冰覆盖范围异常和卫星观测之间的相关系数为0.78。与FIO-ESM参加CMIP5(Coupled Model Intercomparison Project Phase 5)实验结果相比,该同化结果所模拟的北极海冰覆盖范围的长期变化趋势和海冰密集度的空间变化趋势均与卫星观测更加吻合,这说明该同化可为利用FIO-ESM开展北极短期气候预测提供较好的预测初始场。     

Simulation and analysis on seasonal variability of average salinityin the Yellow Sea

The CTD (conductivity, temperature and depth) data collected by six China-Korea joint cruises during 1996-1998 and the climatological data suggest that the seasonal variability of average salinity in the Yellow Sea (Sa) presents a general sinusoid pattern. To study the mechanism of the variability, annual cycles of Sa were simulated and a theoretical analysis based on the governing equations was reported.Three main factors are responsible for the variability: the Yellow Sea Warm Current (YSWC), the Changji-ang (Yangtze) River diluted water (YRDW) and the evaporation minus precipitation (E-P). From December to the next May, the variability of Sa is mainly controlled by the salt transportation of the YSWC. But in early July, the YSWC is overtaken and replaced by the YRDW which then becomes the most important controller in summer. From late September to November, the E-P gradually took the lead. The mass exchange north of the 37癗 line is not significant.     

Wave-induced mixing in the Yellow Sea

Vertical wave-induced mixing parameter Bv expressed in wave number spectrum was estimated in the Yellow Sea. The spatial distributions of By averaged over upper 20 m in 4 seasons were analyzed. It is the strongest in winter because of winter monsoon, and the weakest in spring. Since in summer it plays an important role for circulation of upper layers, its vertical structure was also discussed. Two simulations with and without wave-induced mixing in this season were performed to evaluate its effect on temperature distribution. Numerical results indicate that wave-induced mixing could increase the mixed layer thickness greatly.