| El Nino事件发生和消亡中热带太平洋纬向风应力的动力作用 II.模式结果分析 |
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| 引用本文： | 严邦良,黄荣辉,张人禾.El Nino事件发生和消亡中热带太平洋纬向风应力的动力作用 II.模式结果分析[J].大气科学,2001,25(2):160-172. |
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| 作者姓名： | 严邦良 黄荣辉 张人禾 |
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| 作者单位： | 中国科学院大气物理研究所,北京 100080 |
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| 基金项目： | 国家重点基础研究发展规划项目G1998040900第一部分和国家自然科学基金资助项目49475254、49635180共同资助 |
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| 摘 要： | 为了分析ElNio事件发生和消亡中热带太平洋纬向风应力的动力作用，建立一个类似于Zebiak的简单热带海洋数值模式，在观测到的风应力异常的强迫下，模拟赤道太平洋地区1971年1月至1998年8月海表温度异常的变化。结果表明，模式对观测的Nio3区海表温度异常(SSTA)有很好的模拟能力。模拟和观测Nio3区SSTA之间的相关系数可达0.90。模式对ElNio事件期间赤道太平洋海表温度异常随时间变化也有较好的模拟能力。为了分析ElNio期间SSTA的空间分布及其随时间变化的动力学机制，还对19861989年ENSO循环期间赤道太平洋地区观测的SSTA的传播特征及其形成机制进行了分析。模式较好地模拟出了观测到的赤道太平洋地区SSTA的传播特征，即从1986年底至1987年4月，SSTA具有向东传播的特征，从1987年6月至1988年2月具有向西传播的特征。动力学分析的结果表明，赤道中西太平洋地区的纬向风应力异常对ElNio事件的发生和消亡具有重要作用。赤道中西太平洋地区的西风异常可强迫出东传的Kelvin波，这个东传的Kelvin波对正SSTA的东传起主要作用，当这个东传的Kelvin波到达东边界，由于东边界的反射作用，在东边界产生西传的Rossby波，这个西传的Rossby波对赤道中东太平洋地区正SSTA的西传起主要作用。东传Kelvin波和反射的Rossby波对ElNio期间赤道东太平洋正SSTA二次峰值的形成具有重要作用。
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| 关 键 词： | ElNino事件 Rossby波 Kelvin波 |
Dynamical Role of Zonal Wind Stresses over the Tropical Pacific in the Occurring and Vanishing of El Nio Part II: Analyses of Modeling Results |
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| Yang Bangliang,Huang Ronghui and Zhang Renhe.Dynamical Role of Zonal Wind Stresses over the Tropical Pacific in the Occurring and Vanishing of El Nio Part II: Analyses of Modeling Results[J].Chinese Journal of Atmospheric Sciences,2001,25(2):160-172. |
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| Authors: | Yang Bangliang Huang Ronghui and Zhang Renhe |
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| Abstract: | A simple tropical numerical ocean model similar to Zebiak′s one is built in order to analyze the dynamical role of zonal wind stresses over the tropical Pacific in the occurring and vanishing of El Ni o events. The model is used to simulate the SSTA variability with time from January of 1971 to August of 1998 by the observed wind stress (FSU) forcing. The results show that the model successfully simulates the variability of SSTA in Ni o3 area with time. The correlation coefficient is 0.9 between observational and modeling SSTA over Ni o3 area. The model can better simulate the horizontal SSTA variability with time during El Ni o events. In order to better understand the mechanism of SSTA spatial distribution with time, as an example, we analyze the SSTA propagating characteristics and its causes in the modeling and observational results over the equatorial Pacific in the ENSO cycle between 1986 and 1989. The model better simulates the observational SSTA propagating characteristics over the equatorial Pacific. That is, the SSTA propagates eastward from the end of 1986 to April of 1987 and westward from June of 1987 to February of 1988. The model results show that the zonal wind stress anomaly over the western and middle equatorial Pacific is very important to the occurring and vanishing of El Ni o events. The wind stress anomaly over the western and middle equatorial Pacific can initiate the eastward Kelvin wave. The eastward Kelvin wave is responsible for the SSTA propagating eastward. When the Kelvin wave reaches the east boundary, the westward propagating Rossby waves are initiated because of east boundary reflection. The westward propagating Rossby waves are responsible for SSTA propagating westward over the equatorial eastern Pacific. The propagating eastward Kelvin wave and the propagating westward Rossby waves from east boundary reflection are responsible for the second peak of SSTA in El Ni o events over the east equatorial Pacific. |
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