Intraseasonal variations in the tropical Western Hemisphere and the generation mechanism of stratospheric Kelvin waves

热带西半球季节内变化与平流层开尔文波的产生机制

• 批准号: 03640385
• 负责人: ITOH Hisanori
• 金额: $ 0.9万
• 依托单位: Wakayama University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03640385/
• 关键词: Intraseasonal variation; Stratospheric Kelvin wave; Rossby wavetrain; Angular momentum; Tropical-extratropical interaction; プリミティブ・モデル

Four problems about the atmospheric response to tropical heating were tackled using numerical models based on the primitive equations on the sphere. The model heating was given as an external forcing.The first problem is to clarify the role of nonstationarity in the response to stationary heating. For this purpose, time integration and stationary models are constructed. In parameter ranges for which stationary solutions are unstable, results from the both models show a significant difference in anomaly fields. That is, the time mean yielded from the time integration model has larger amplitudes than the stationary solution. Further, Rossby wavetrains radiating from the tropical heat source go through the midlatitude, again returning to the tropics. Thus, wave amplitudes become large even in regions which are far from the heat source.Next, we examine the role of the tropical-extratropical interaction in the intraseasonal variation. Heating in this model moves from 60E to 180ﾟ, having the … More period of 40days. When there is no tropical-extratropical interaction, i.e., the zonal mean flow in midlatitudes is weak, the amplitude of the intraseasonal variation is large only near the heat source centered 120E. In contrast, when the midlatitude westerly is strong, wavetrains starting from the tropics pass through the midlatitude, returning to the tropics. Then, the intraseasonal variation amplifies in the Western Hemisphere.Variations of the atmospheric angular momentum (AAM) are also examined in the same model. It is found that the source of the AAM associated with the intraseasonal variation does not lie in the equatorial region but the subtropics. The equatorial region is the apparent source, since the AAM is transported from the subtropics to the equator. It is also clarified that Rossby wavetrains play an important role in the acquisition and transportation of the AAM.Finally, numerical experiments are performed, in order to examine the hypothesis that stratospheric Kelvin waves are generated from the tropospheric intraseasonal variation in the Western Hemisphere. We have not so far obtained a positive result about this hypothesis. Less

使用基于球体上原始方程的数值模型来解决有关大气反应的四个问题。将模型加热作为外部强迫。第一个问题是阐明非机构性在对固定加热反应中的作用。为此，构建了时间集成和固定模型。在固定溶液不稳定的参数范围内，两种模型的结果均显示出异常场的显着差异。也就是说，从时间积分模型中产生的时间平均值比固定解的放大器更大。此外，从热带热源辐射的Rossby Wavetrain经过中纬度，再次返回热带。这是，即使在远离热源的区域，波浪放大器也会变得很大。隔离，我们检查了热带 - 肠道相互作用在季节内变异中的作用。该模型的加热从60E移动到180 ﾟ，具有40天的时间。如果没有热带界面相互作用，即，中纬度的区域平均流量很弱，季节内变异的放大器仅在以120E为中心的热源附近很大。相比之下，当中纬度西部强大时，从热带开始的波浪形开始，穿过中纬度，返回热带。然后，在同一模型中还检查了西半球的季节内变异放大器。发现与季节内变异相关的AAM的来源不在于等效区域，而在于亚热带。等效区域是明显的来源，因为AAM从亚热带传输到等效性。还可以澄清说，罗斯比波（Rossby Wabetrains）在AAM的采集和运输中起着重要作用。在最终的数值实验上，进行了数值实验，以检查以下假说，即西半球的对流层内变化产生了平流层开晶波。到目前为止，我们还没有对这一假设获得积极的结果。较少的

项目成果

伊藤 久徳: "熱帯熱源による熱帯ー中緯度間相互作用" グロ-スベッタ-. 30. (1992)

Hisanori Ito：“热带热源导致的热带-中纬度相互作用”Grosbetta 30。（1992）