Planetary Wave Dynamics: Implications of Bimodality

行星波动力学：双峰性的影响

• 批准号: 8721728
• 负责人: Anthony Hansen
• 金额: $ 19.14万
• 依托单位: Control Data Corporation
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1988
• 资助国家: 美国
• 起止时间: 1988-04-01 至 1990-09-15
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8721728&HistoricalAwards=false
• 关键词: Planetary; Wave; Dynamics; Implications; Bimodality

Recent studies of intraseasonal, low frequency variability in midlatitudes of the Northern Hemisphere have strongly suggested that the probability density distributions of the planetary long waves (k = 2 to 4) are significantly bimodal. In contrast, the speed, horizontal and vertical shear of the zonal mean flow possess unimodal probability density distributions. The physical basis for such partitioning has not yet clear. The possibility that the bimodal structures are an artifact of data stratification method or numerical truncation during assimilation has not yet been discounted either. The present study addresses these issues through further dignostic analyses of observational data and numerical model simulations. The Northern Hemisphere data would be examined to delineate the processes involved in transitions between the two modes for the planetary long waves and analysis extended to include the Southern Hemisphere data. Output from selected long integrations of a general circulation model simulations will be analysed to determine the probability density distribution functions of model planetary long waves. The possible influence of bimodality on the predictive skill of global numerical forecasts would be evaluated. This work would contribute to our basic understanding of the dynamical process important in intraseasonal climate variability.

季节内低频变异性的最新研究 在北方半球的中纬度地区， 表明，概率密度分布的 行星长波（k = 2 ~ 4）是显著的双峰型。 在 相反，纬向速度、水平切变和垂直切变 平均流量具有单峰概率密度分布。 这种划分的物理基础尚不清楚。 的 双峰结构可能是数据的伪影 同化过程中分层方法或数值截断 也没有被打折。 本研究报告阐述 这些问题，通过进一步的诊断分析的观察 数据和数值模型模拟。 北方半球 将对数据进行检查，以描述 行星长波两种模式之间的转换 并将分析扩展到包括南半球的数据。 大气环流的选定长积分的输出 将对模型模拟进行分析，以确定 模型行星长波的密度分布函数。 双峰对预测能力的可能影响 将评估全球数值预报。 这项工作将 有助于我们对动力学过程的基本理解 在季节内气候变化中很重要。