A Modeling Study of the Intrinsic Variability of the Gulf-Stream and Kuroshio Extension Systems

湾流和黑潮扩展系统内在变异性的模拟研究

• 批准号: 0221516
• 负责人: Francois Primeau
• 金额: --
• 依托单位: University of California-Irvine
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2007-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0221516&HistoricalAwards=false
• 关键词: Modeling; Study; Intrinsic; Variability; Gulf

0221516 PrimeauThe purpose of this project is to test the hypothesis that the observed variability is a manifestation of intrinsic variability associated with the transitions between multiple equilibria. To do this the investigators will apply the recently developed methods of numerical bifurcation analysis to a hierarchy of ocean models with increasing realism to compute the solution branches found in the simpler model. The following clear criteria will be tested. If they are not met, the hypothesis must be rejected. 1. The equilibria with elongated recirculation gyres should be relatively less unstable than the equilibria with elongated gyres to be consistent with the observation that eddy activity decreases during periods of elongated gyres 2. The unstable modes associated with elongated recirculation gyres should have amplitude patterns that dominate in the downstream region of the jet, and those for the contracted recirculation gyres should have amplitude patterns that dominate in the upstream region, to be consistent with the observation that the eddy variability moves downstream during elongated states.3. The mean zonal path of the jet extension should be further north for equilibria with elongated recirculation gyres to be consistent with the observation that the zonal mean path of the Gulf Stream and Kuroshio Extension moves northward during elongated states.Through this study a Ph.D. student will be trained in ocean modeling and in the application of dynamical systems theory to climate problems. In addition a software package to do numerical bifurcation analysis of ocean models will be produced and made available to the community. The possibility that the observed large-scale patterns of low-frequency variability are the result of intrinsic variability is an exciting one because observations show that these current changes are signi?cant contributors to the maintenance sea surface temperature anomalies and thus could contribute to mid-latitude climate variability.

[0221516]本项目的目的是检验这样一个假设，即观察到的变异性是与多个平衡之间的过渡相关的内在变异性的表现。为了做到这一点，研究人员将把最近发展的数值分岔分析方法应用于越来越现实的海洋模型层次，以计算在更简单的模型中发现的解分支。将测试以下明确的标准。如果不满足，则必须拒绝该假设。1. 延长环流的平衡应该比延长环流的平衡相对更不稳定，以符合在延长环流期间涡旋活动减少的观察结果2。与延长的再循环环流相关的不稳定模态应该具有在急流的下游区域占主导地位的振幅型，而与收缩的再循环环流相关的不稳定模态应该具有在上游区域占主导地位的振幅型，以与在延长状态下涡变率向下游移动的观察相一致。在环流拉长的平衡状态下，急流延伸的平均纬向路径应向北移动，这与墨西哥湾流和黑潮延伸在拉长状态下向北移动的平均纬向路径一致。通过这项研究，博士生将在海洋建模和动力系统理论在气候问题中的应用方面得到训练。此外，还将编制一个软件包，对海洋模型进行数值分岔分析，并提供给社区使用。观测到的低频变率的大规模模式是内在变率的结果，这种可能性令人兴奋，因为观测表明，这些当前的变化是显著的。它们对维持海表温度异常有贡献，因此可能对中纬度气候变率有贡献。