Low-Frequency Variability of Troposphere-stratosphere Coupling

对流层-平流层耦合的低频变化

• 批准号: 9405448
• 负责人: Mark Baldwin
• 金额: $ 22.38万
• 依托单位: NorthWest Research Associates, Incorporated
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-06-15 至 1997-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9405448&HistoricalAwards=false
• 关键词: Low; Frequency; Variability; Troposphere; stratosphere

9405448 Baldwin On timescales from a week through interannual there is considerable variability of tropospheric flow patterns. This study will focus on understanding how much of the low-frequency variability of the stratosphere can be accounted for by stationary wave patterns in the troposphere. The general approach will be to identify patterns in the mid-troposphere that are linked with stratosphere flow. Particular attention will be paid to the possible influences of El Nino/Southern Oscillation (ENSO) on the stratosphere that may be communicated through modulation of the extratropical tropospheric flow. The PI will use empirical orthogonal function (EOF) analysis and singular value decomposition (SVD) analysis of the tropospheric height field together with correlations, composites and spectral analysis to identify modes which, on interannual and interseasonal timescales, seem to have a significant stratospheric influence. The complementary nonlinear technique of cluster analysis will also be used. A series of experiments using a GCM with simplified physics will be used to study the response of the middle atmosphere to tropospheric circulation anomalies. The experiments will be designed to determine the model's stratospheric response to tropospheric anomaly patterns. Comparing the response of the model's winter stratosphere with the resultq of the data analysis should provide a valuable method of identifying the contribution to winter stratospheric interannual variability from tropospheric anomalies. As part of this study the PI will use gridded ECMWF data analyses in conjunction with rawinsonde data, to determine tropical tropospheric horizontal wave structure to better elucidate the different types of synoptic-scale disturbances that exist in the tropical troposphere and their vertical coupling, if any, to the stratosphere. The focus is specifically on organized, westward- traveling, synoptic-scale waves in the tropical lower atmosphere that may be involved in the excitation of Rossby-gravity waves. Disturbances in both lower and upper troposphere will ne investigated, as will any vertical coupling between the two layers. This research is important because it should enhance our understanding of important climate processes related to stratospheric-tropospheric dynamics.

小行星9405448 从一周到年际的时间尺度上，对流层流型有相当大的变化。 这项研究的重点是了解对流层中的驻波模式可以解释多少平流层的低频变率。 总的办法是查明与平流层气流有关的对流层中部的模式。 将特别注意厄尔尼诺/南方涛动对平流层可能产生的影响， 通过对流层外对流层气流的调制进行通信。 PI将使用对流层高度场的经验正交函数分析和奇异值分解分析，以及相关性、合成物和谱分析，以确定在年际和季节间时间尺度上似乎对平流层有重大影响的模式。 还将使用聚类分析的补充非线性技术。 将利用具有简化物理学的大气环流模式进行一系列实验，研究中层大气对对流层环流异常的响应。 实验的目的是确定模型的平流层对对流层异常模式的反应。 将模式的冬季平流层响应与数据分析的结果进行比较，应提供一种有价值的方法，以确定对流层异常对冬季平流层年际变率的贡献。 作为这项研究的一部分，PI将使用网格ECMWF数据分析结合rawinsonde数据，以确定热带对流层水平波结构，以更好地阐明热带对流层中存在的不同类型的天气尺度扰动及其与平流层的垂直耦合（如果有的话）。 重点是在热带低层大气中有组织的，向西行的，天气尺度的波，可能参与激发的Rossby重力波。 对流层低层和高层的扰动以及两层之间的任何垂直耦合都将受到研究。 这项研究之所以重要，是因为它将增进我们对与平流层-对流层动力学有关的重要气候过程的了解。