地球系统模式FIO-ESM对ENSO现象模拟能力的评估与分析

发布时间：2018-03-13 11:10

本文选题：ENSO　切入点：地球系统模式FIO-ESM　出处：《国家海洋局第一海洋研究所》2017年硕士论文　论文类型：学位论文

【摘要】：厄尔尼诺-南方涛动(ENSO)是全球最显著的年际海气耦合现象,对全球的天气与气候都有着重要的影响。当前海气耦合数值模式已经成为ENSO模拟与预测的重要工具,然而对参与最近的CMIP5(Coupled Model Intercomparison Project Phase 5)的多模式模拟结果分析表明海气耦合模式对ENSO的模拟仍存在较大的偏差。本文首先与观测对比评估了国家海洋局第一海洋研究所地球系统模式(FIO-ESM)历史实验(Historical)模拟ENSO现象以及热带太平洋基本状态的能力,进而通过上层海洋热收支手段对模式中厄尔尼诺(El Ni?o)和拉尼娜(La Ni?a)现象分别进行了分析,以探究ENSO演变过程中海洋热力学、动力学以及海气耦合的作用。与观测对比分析表明FIO-ESM模式能够较好地模拟出ENSO期间热带太平洋海表面温度、风场、降水变化的基本特征,但仍存在一些模拟偏差,如模拟的热带东太平洋平均海表面温度偏高,信风强度偏弱,ENSO周期的不规则性较弱,振幅偏强,厄尔尼诺事件出现东传的特性,ENSO到达盛期的时间也出现偏差。本文研究表明,纬向、经向、垂向的热量输运和海表面热通量都对ENSO的发展和消亡过程有着突出贡献:FIO-ESM模拟结果中,异常纬向流和平均垂向流导致的热量输运(纬向平流反馈与温跃层反馈)引导着ENSO的成长与衰退,控制ENSO的整个演变过程;由异常垂向流与平均经向流导致的热量输运使ENSO时期异常的海温得到进一步增强,影响着ENSO的强度;海表面热通量与SST异常反位相,对ENSO的成长起着反作用。对上层海洋热收支的进一步分析表明,对赤道太平洋地区海表面平均风场、温度场的模拟偏差会影响到ENSO发生时上层海洋温度场、流场的分布,进而导致模式对纬向、经向、垂向热量输运的模拟出现偏差。FIO-ESM模式模拟热带东太平洋平均SST偏高,在厄尔尼诺期间引发强烈的西风异常。模式对西风异常的模拟偏差增强了温跃层反馈的作用,会加剧ENSO的振荡幅度,减弱其周期的不规则性,并且由温跃层反馈主导的厄尔尼诺事件会出现东传的特征。由于模式模拟的冬季热带太平洋信风减弱、东太平洋冷舌收缩,减弱了冬季纬向平流反馈与温跃层反馈的作用,导致ENSO的季节锁相出现偏差。
[Abstract]:El Nino-Southern Oscillation (ENSO) is the most significant annual air-sea coupling phenomenon in the world, which has an important impact on the weather and climate of the world. At present, the coupled air-sea numerical model has become an important tool for ENSO simulation and prediction. However, the analysis of the results of the multi-model simulation involving the recent CMIP5(Coupled Model Intercomparison Project Phase 5 shows that there is still a large deviation between the air-sea coupling model and the ENSO simulation. This paper first evaluates the first Oceanic Research Institute of the State Oceanic Administration by comparison with observations. The Earth system Model (FIO-ESM) Historical experiment is capable of simulating ENSO phenomena and the basic state of the tropical Pacific Ocean. Then the El Nino El Ni? ) and La Ni? (a) the phenomena are analyzed in order to explore the role of ocean thermodynamics, dynamics and air-sea coupling in the evolution of ENSO. The comparison with observations shows that the FIO-ESM model can well simulate the sea surface temperature and wind field in the tropical Pacific during ENSO. The basic characteristics of precipitation change, but there are still some simulation deviations, such as high mean sea surface temperature in the tropical eastern Pacific, weak trade wind intensity and weak irregular and strong amplitude of ENSO period. The characteristics of eastward propagation of El Nino events and the time of ENSO reaching its peak are also deviated. The results of this paper show that, in zonal and meridional directions, Both vertical heat transport and sea surface heat flux contribute significantly to the development and extinction of ENSO. The anomalous zonal flow and the average vertical flow lead to the heat transport (zonal advection feedback and thermocline feedback) leading to the growth and decline of ENSO and controlling the whole evolution process of ENSO. The heat transport caused by the anomalous vertical current and the average meridional current further strengthens the abnormal SST during the ENSO period, which affects the intensity of the ENSO, and the inverse phase of the sea surface heat flux and the SST anomaly. A further analysis of the upper ocean thermal budget shows that for the equatorial Pacific ocean surface mean wind field, the simulation deviation of the temperature field will affect the upper ocean temperature field and the distribution of the current field when ENSO occurs. This results in the deviation of the model from the zonal, meridional and vertical heat transport. FIO-ESM model simulates the high average SST of the tropical eastern Pacific. Strong westerly anomalies are triggered during El Nino. The simulated deviation of the model for westerly anomalies enhances the thermocline feedback, exacerbates the oscillation amplitude of ENSO and weakens the irregularity of its periodicity. Due to the weakening of the tropical Pacific trade wind in winter and the contraction of the cold tongue in the eastern Pacific Ocean, the effect of latitudinal advection feedback and thermocline feedback on winter latitudinal advection and thermocline feedback is weakened. Causes the ENSO seasonal lock phase to appear the deviation.
【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】：2017
【分类号】：P732

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