The Dynamics of Westerly Jets

西风急流的动力学西风急流在旋转行星的大气和海洋环流中无处不在。在地球的大气层中，西风急流组织天气，并调解重要的痕量气体的运输。李将研究决定喷流结构及其对气候变化的反应的动力学机制。研究将集中在三个方面的射流：它们与“楼梯”的守恒量的分布，最显着的位涡。在喷流之间存在守恒量的平坦区域--“台阶”。这意味着混合在这些区域是有效的。射流中心具有守恒量的急剧梯度，这意味着射流是混合的障碍。Lee将生成具有不同参数设置和不同喷气配置的模型运行的清单。这些将被分析，以确定控制混合的机制，从而设置staircasesJets的结构是自我维护和自我锐化。 这导致了这样一种可能性，即对于一组给定的气候参数，可能有不止一种可能的射流排列。随着气候的变化，环流可能从一种形态跳到另一种形态。李将开发一个理论的流体动力通量，维持射流。根据这一理论对多重平衡的预测将在数值模式中得到检验。南半球的急流、飓风中的急流以及旋转球体上湍流的理想化模拟都表现出螺旋结构。Lee将使用她的模拟目录，连同沿着的热带加热模拟，来测试关于允许螺旋喷流作为稳定结构存在的条件的假设。更广泛的影响包括培训研究生，并将研究成果纳入PI教授的气候动力学课程。她还计划让本科生参与她的研究。

The dynamics of westerly jetsWesterly jets are ubiquitous in the circulations of atmospheres and oceans on rotating planets. In Earth's atmosphere westerly jets organize the weather and they mediate the transport of important trace gases. Lee will investigate the dynamical mechanisms that determine the structure of jets and their responses to climate change. The research will focus on three aspects of jets: They are associated with "staircases" in the distributions of conserved quantities, most notably the potential vorticity. There are flat regions of conserved quantities - the "steps" - between jets. This implies that mixing is effective in these regions. The centers of jets feature sharp gradients in conserved quantities, implying that jets are barriers to mixing. Lee will generate an inventory of model runs with different parameter settings and with different jet configurations. These will be analyzed to determine the mechanisms that control mixing and thus set the structures of the staircasesJets are self-maintaining and self-sharpening. This leads to the possibility that there can be more than one possible arrangement of jets for a given set of climate parameters. As the climate changes, the circulation may jump from one configuration to another. Lee will develop a theory for the fluid-dynamical fluxes that maintain the jets. Predictions of multiple equilibria from this theory will be tested in numerical models.Jets in the Southern Hemisphere, within hurricanes, and in idealized simulations of turbulence on a rotating sphere, all exhibit spiral structures. Lee will use her catalog of simulations, along with additional simulations with tropical heating, to test hypotheses about the conditions that permit spiral jets to exist as stable structures.Broader impacts include training graduate students and incorporating research results in a course in climate dynamics taught by the PI. She also plans to involve undergraduates in her research.