Title: Resonance-Driven Intermittency and Extreme Events in Turbulent Scalar Transport with a Mean Gradient Show Chinese title

Title: 具有平均梯度的湍流标量传输中的共振驱动间歇性和极端事件

Abstract: We study the statistical properties of passive tracer transport in turbulent flows with a mean gradient, emphasizing tracer intermittency and extreme events. An analytically tractable model is developed, coupling zonal and shear velocity components with both linear and nonlinear stochastic dynamics. Formulating the model in Fourier space, a simple explicit solution for the tracer invariant statistics is derived. Through this model we identify the resonance condition responsible for non-Gaussian behavior and bursts in the tracer. Resonant conditions, that lead to a peak in the tracer variance, occur when the zonal flow and the shear flow phase speeds are equivalent. Numerical experiments across a range of regimes, including different energy spectra and zonal flow models, are performed to validate these findings and demonstrate how the velocity field and stochasticity determines tracer extremes. These results provide additional insight into the mechanisms underlying turbulent tracer transport, with implications for uncertainty quantification and data assimilation in geophysical and environmental applications. Show Chinese abstract

Abstract: 我们研究了具有平均梯度的湍流中被动示踪剂输运的统计特性，重点是示踪剂的间歇性和极端事件。 建立了一个可解析分析的模型，将纬向速度分量和剪切速度分量与线性和非线性随机动力学耦合起来。 通过在傅里叶空间中构建模型，推导出了示踪剂不变统计量的一个简单显式解。 通过该模型，我们识别出导致示踪剂非高斯行为和爆发的共振条件。 当纬向流速和剪切流速的相速度相等时，会导致示踪剂方差峰值的共振条件出现。 针对涵盖不同能量谱和纬向流模型的各种参数范围进行了数值实验，以验证这些发现，并展示速度场和随机性如何决定示踪剂的极端值。 这些结果为进一步理解湍流示踪剂输运背后的机制提供了额外的见解，这对地球物理和环境应用中的不确定性量化和数据同化具有重要意义。