Collaborative Research: Dynamics of Subtropical Humidity

合作研究：副热带湿度动态

• 批准号: 0542388
• 负责人: Joseph Galewsky
• 金额: --
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-02-01 至 2011-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0542388&HistoricalAwards=false
• 关键词: Collaborative; Research; Dynamics; Subtropical; Humidity

The water vapor feedback is the most important mechanism for amplifying the climatic response to increased anthropogenic greenhouse gases. The dry regions of the subtropical free troposphere play an especially important role in determining the strength of this feedback. The humidity in the dry subtropics depends on the temperature at which saturation was last encountered by air parcels at remote locations along the ensemble of trajectories that terminate in the subtropics at a given time. Changes in the water vapor feedback depend on how these statistics of last saturation may change as the climate warms. A tracer-based technique is developed for diagnosing the statistics of last saturation in Global Climate Models (GCMs) and reanalysis data. The research objective of this work is to use these diagnostic techniques to better understand the processes that control the humidity of the subtropics in modern and future climates. Intellectual merit: Completion of this work will result in (1) development of the statistics of last saturation within the modern climate of the subtropics, as recorded in reanalysis data and in GCM simulations, with a focus on seasonal and interannual variability and on the roles of extratropical eddies and the Hadley and Walker circulations in controlling subtropical humidity; (2) further understanding of how the last saturation statistics may change under global warming scenarios; (3) examination of the mechanisms controlling subtropical humidity at a more basic, process-oriented level using idealized GCMs. Broader impacts: The research will provide training to two graduate students in diagnostic analysis of tropical moisture variability and impacts on present and future global climates. The results will aid the broader climate change assessment efforts and will be of potential benefit for societal and policy considerations.

水蒸气反馈是放大气候对人为温室气体增加反应的最重要机制。亚热带自由对流层的干燥区在决定这种反馈的强度方面起着特别重要的作用。干燥亚热带地区的湿度取决于在某一特定时间终止于亚热带地区的轨迹集合上偏远地区的空运包裹最后到达饱和时的温度。随着气候变暖，水蒸气反馈的变化取决于这些最后饱和度的统计数据如何变化。提出了一种基于示踪剂的全球气候模式（GCMs）和再分析数据的最后饱和统计诊断技术。这项工作的研究目的是利用这些诊断技术来更好地了解控制现代和未来气候中亚热带湿度的过程。知识价值：这项工作的完成将导致(1)在再分析数据和GCM模拟中记录的现代亚热带气候中最后饱和的统计数据的发展，重点关注季节和年际变化以及温带涡旋和哈德利和沃克环流在控制亚热带湿度方面的作用；(2)进一步了解全球变暖情景下的末次饱和统计数据的变化；(3)利用理想gcm在更基本的、面向过程的水平上研究控制副热带湿度的机制。更广泛的影响：这项研究将为两名研究生提供培训，对热带湿度变化及其对当前和未来全球气候的影响进行诊断分析。这些结果将有助于更广泛的气候变化评估工作，并将对社会和政策考虑产生潜在的好处。