【作者】 黄传江；

【导师】 王伟；

【作者基本信息】 中国海洋大学 ， 物理海洋， 2006， 博士

【摘要】 跨越等密度面的混合(diapycnal mixing,下面简称为混合)控制着海洋中的热盐环流和向极热输送,对全球气候系统的维持和变化有重要影响。海洋中的混合过程是由风和潮汐输入的机械能维持的,这些机械能的变化会导致海洋中混合率的变化。最近一些研究表明,在过去几十年里,全球风输入到海洋中的机械能发生了大的年际到年代际时间尺度的变化,因此海洋中的混合率也应该存在相应的变化。考虑到风输入到海洋中机械能的年际到年代际变化,利用一个大洋环流模式,本文研究了混合率的年际到年代际变化对赤道太平洋的影响。本文采用的模式是Hallberg Isopycnal Model(HIM),这是一个等密度面坐标模式,其优点是可以有效地避免z-坐标模式中水平混合和平流引起的虚假跨密度面混合。本文的模式域是30 o S~30 o N之间的赤道太平洋地区。在本文的实验中,混合率在整个模式域内,或者模式域内的部分地区是周期性变化的。此外,本文还运行了混合率和风应力在模式域内同时变化的实验。本文的研究结果表明,当混合率在整个模式域内周期性变化时,赤道太平洋地区的海表温度和环流系统等都出现了一系列周期性的变化,其中最明显的变化是出现在赤道地区中-东部,特别是Nino3区(5 o S~5 o N,150 oW ~90 oW )的海表温度异常(SSTA)。当混合率呈现正异常时,Nino3 SSTA为负异常;而当混合率呈现负异常时,Nino3 SSTA为正异常。当混合率变化的振幅一定时,Nino3 SSTA的变化幅度随混合率变化周期的增长而增大;而当混合率变化周期一定时,Nino3 SSTA的变化幅度随混合率振幅的增大呈线性增大。在动力学上,模式中Nino3 SSTA的变化是由混合率变化诱发的赤道环流系统的变化以及大尺度波动引起的。当混合率为正异常时,强烈的混合将更多的次表层冷水夹卷到表层,致使表层温度降低。在Nino3区,温跃层较浅,冷水更容易被夹卷到海面,因此那里的SSTA变化最明显。另一方面,海洋上层的冷却导致海平面的降低,进而引起海盆东西方向压强梯度力的变化,这种变化增强了赤更多还原

【Abstract】 Diapycnal mixing process, which control Meridional overturning circulation and polarward heat transport in the oceans, plays a vitally important role in global climate and climate change. Since it is sustained by the wind and tide energy input to the oceans, diapycnal mixing coefficient (DMC) will vary along with the change of external energy input. Recent studies showed that the wind energy input to the global oceans has changed greatly interannually to interdecadally over the past decades, so it will be naturally that the DMC in the oceans would has a great change correspondingly.In view of interannual to interdecadal variability of wind energy input, climate variability in the equatorial Pacific Ocean induced by interannual to interdecadal variability of DMC has been examined. The Hallberg Isopycnal Model (HIM) has been used in this study. HIM is an Oceanic General Circulation Model (OGCM) based on the isopycnal coordinate, whose advantage is that it can effectively avoid artificial diapycnal mixing associated with the horizontal mixing/advection in the z-coordinate model. The model domain covers the equatorial Pacific between 30 o S and 30 o N. In the numerical experiments of this study, DMC oscillates periodically either in the whole model domain or in part of the domain. Moreover, the experiments that both wind and DMC oscillate periodically in the domain are also run.As DMC oscillates periodically, both surface temperature and current system are forced into periodic changes in these experiments, in which the most outstanding one is sea surface temperature anomaly (SSTA) in the central and eastern equatorial Pacific, especially in Nino3 region (5 o S~5 o N, 150 oW ~90 oW ). Nino3 SSTA is in更多还原