Eddy-Jet Interaction and Climate

涡流喷射相互作用和气候

• 批准号: 0750916
• 负责人: Noboru Nakamura
• 金额: --
• 依托单位: University of Chicago
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-02-15 至 2011-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0750916&HistoricalAwards=false
• 关键词: Eddy; Jet; Interaction; Climate

In the context of climate change, detecting long-term modulations in the general circulation and in the global transport of tracers is important, but it is made difficult by the low signal-to-noise ratio. Dr. Nakamura will alleviate this problem by introducing a new partition between the eddies and the background flow and their interaction. Preliminary results using this novel method have been obtained, and a global, multi-year amplification of the eddies and jets, over the period 2001-5 is revealed. This amplification is not detected using traditional methods. This method will be applied to meteorological analyses and to long-term climate-model simulations under global warming scenarios, to measure the frequency and intensity of modulations of the general circulation. Idealized models (shallow water and two-level models) will be employed to explore the dynamics that underlies such modulations.The effects of jets and their modulations on global mixing properties will be studied using a passive tracer subject to advection by the observed large-scale flow together with small-scale diffusivity. The decay rate of the variance of the tracer is a metric of global mixing, and contributions from the jet regions to the decay rate will be quantified with a new diagnostic.The proposed activity will provide a new diagnostic platform for the tropospheric general circulation and transport, suitable for the detection of long-term shifts in the climatic regime. The Lagrangian-mean approach bypasses the complication of eddy-mean flow interaction in the traditional sense, and it allows simpler interpretations in terms of nonconservative processes.The broader impacts of this activity are that the diagnostic framework can be applied to a wide class of flows, including the stratosphere, troposphere, possibly the oceans, and numerical simulations. Two graduate students will be supported.

在气候变化的背景下，探测大气环流和示踪剂全球运输的长期调制是重要的，但由于信噪比较低，这一工作变得困难。Nakamura博士将通过在涡流和背景流及其相互作用之间引入新的分区来缓解这个问题。利用这种新方法已经获得了初步结果，并揭示了2001-5年期间涡旋和喷流的全球多年放大。使用传统方法无法检测到这种扩增。这种方法将应用于全球变暖情景下的气象分析和长期气候模式模拟，以测量大气环流调制的频率和强度。理想化的模型（浅水和两级模型）将被用来探索这种调制背后的动力学。射流及其调制对整体混合特性的影响将使用一种被动示踪剂进行研究，该示踪剂受到观测到的大尺度流动和小尺度扩散的平流的影响。示踪剂方差的衰减率是全球混合的度量，射流区域对衰减率的贡献将通过一种新的诊断来量化。拟议的活动将为对流层环流和运输提供一个新的诊断平台，适合于探测气候制度的长期变化。拉格朗日平均方法绕过了传统意义上的漩涡-平均流相互作用的复杂性，并且它允许在非保守过程方面进行更简单的解释。这项活动的更广泛的影响是，诊断框架可以应用于广泛的流动类别，包括平流层、对流层，可能还有海洋，以及数值模拟。将资助两名研究生。