2013年Wyrtki急流变异及影响机制分析

发布时间：2018-05-19 16:39

本文选题：Wyrtki急流 + 热带印度洋　；参考：《国家海洋局第一海洋研究所》2016年硕士论文

【摘要】：受西南季风和东北季风转换时期的赤道纬向西风影响,赤道印度洋每年春季和秋季会出现两次东向Wyrtki急流(WJ)。WJ影响着热带印度洋上层海洋的动量、盐度和热量的纬向输送,对印度洋海盆尺度海气相互作用产生影响。WJ存在多时间尺度变化,特别是显著的年际变化。本研究利用观测资料揭示了2013年春季和秋季WJ的异常变化,主要表现为:春季WJ强度强于秋季,并且秋季WJ盛期峰值出现在12月,以上特征与平均态下的WJ演化特征显著不同。在气候平均态情况下,春季WJ强度比秋季弱,并且秋季WJ盛期出现在11月,12月WJ已经逐渐衰弱。进一步分析表明,2013年春季WJ异常与赤道印度洋海表风场变化密切相关,而春季印度洋海表风场的变化主要归因于2013年春季异常增强的季节内振荡(ISO)事件。2013年5月与12月的ISO对流位相是赤道印度洋海表出现强西风异常的主要原因。为更好了解2013年WJ异常现象,我们接下来使用大气风场驱动的POM模式对2013年WJ现象进行了数值模拟。控制实验表明,POM模式可以较好模拟气候态WJ主要特征,敏感性实验结果证明,2013年热带印度洋海表纬向西风的季节内信号对WJ产生了有重要影响。海气耦合模式是我们对未来气候变化进行评估的重要工具,而CMIP模式代表了世界上目前最先进的耦合数值模式,并为我们评估耦合模式对WJ的模拟能力提供了很好的平台。我们使用24个CMIP5模式初步评估了耦合模式对WJ的模拟能力。结果表明,CMIP5模式可以模拟出气候态WJ的空间分布特征和季节演化特征,但是各个模式之间模拟结果有较大的差别。同观测资料相比,一些模式模拟的秋季WJ延迟一个月达到盛期。进一步诊断分析表明,模式模拟得到的热带印度洋海表纬向风对秋季WJ有重要影响。
[Abstract]:Influenced by the equatorial zonal westerly wind during the transition between the southwest monsoon and the northeast monsoon, the equatorial Indian Ocean occurs twice a year in spring and autumn with an eastward Wyrtki jet, WJ. WJ. WJ, which affects the zonal transport of momentum, salinity and heat in the upper tropical Indian Ocean. There is a multi-time scale change in WJ, especially the significant interannual variation. In this study, the anomalous changes of WJ in spring and autumn in 2013 were revealed by using observational data. The results showed that the intensity of WJ in spring was stronger than that in autumn, and the peak value of WJ in autumn appeared in December, which was different from the evolutional characteristics of WJ in average state. The strength of WJ in spring is weaker than that in autumn, and the peak of WJ in autumn appears in November and weakens gradually in December. Further analysis shows that the WJ anomaly in spring 2013 is closely related to the variation of the surface wind field in the equatorial Indian Ocean. The variation of the surface wind field in the Indian Ocean in spring is mainly attributed to the intraseasonal oscillation ISO) event, which is characterized by the enhancement of the anomaly in the spring of 2013. The ISO convective phase in May and December 2013 is the main reason for the strong westerly anomaly on the surface of the equatorial Indian Ocean. In order to better understand the 2013 WJ anomaly, we use the atmospheric wind field driven POM model to simulate the 2013 WJ phenomenon. The control experiments show that the POM model can well simulate the main characteristics of climate WJ, and the sensitivity experiment results show that the intraseasonal signal of the tropical Indian Ocean sea surface zonal westerly in 2013 has an important influence on WJ. The air-sea coupling model is an important tool for us to evaluate the future climate change, while the CMIP model represents the most advanced coupled numerical model in the world, and provides a good platform for us to evaluate the simulation ability of the coupled model to WJ. We used 24 CMIP5 models to evaluate the simulation capability of WJ. The results show that CMIP5 model can simulate the spatial distribution and seasonal evolution of climatic WJ, but the simulation results are quite different among the models. Compared with the observed data, the autumn WJ of some model simulations is delayed by one month to its peak. Further diagnostic analysis shows that the tropical Indian Ocean sea surface zonal wind simulated by the model has an important effect on the autumn WJ.
【学位授予单位】：国家海洋局第一海洋研究所
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P732

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