论文标题
表面准确性湍流中的浮力楼梯极限
The buoyancy staircase limit in surface quasigeostrophic turbulence
论文作者
论文摘要
在准真诚液上的表面浮力梯度允许存在被捕获的罗斯比波。这些rossby波与表面准神经性湍流的相互作用导致纬度不均匀混合，在某些条件下，在某些条件下，在表面浮力楼梯中达到顶点：一种子午浮力谱：由锋利的浮力梯度组成，由锋利的浮力梯度组成，其锋利的浮力梯度和较尖锐的处于尖锐的梯度和弱梯度之间。在本文中，我们研究了表面准神经性湍流中这种浮力楼梯极限的出现，并研究了所得动力学对垂直分层的依赖性。过度减少分层[$ \ mathrm {d} n（z）/\ mathrm {d} z \ leq0 $，其中$ n（z）$是浮力频率]，我们获得的交互范围更长（比统一分层）和高度分散的rossby波。在楼梯限制中，我们发现直射流沿喷射波向东繁殖，类似于二维正压$β$ - 平面湍流。相反，通过增加分层[$ \ mathrm {d} n（z）/\ mathrm {d} z \ geq0 $]，我们获得了具有较短相互作用范围和弱分散性rossby wave的流量。在楼梯限制中，我们发现弯曲的喷气机具有大纬度曲折，其形状由于沿射流波的弱色散而向西传播而在及时演变。这些沿射流波比分层增加的幅度更大，而不是过度降低分层，因此，与分层相比，与分层的增加相比，域平均区域与子午速度的比率是小的两到三倍。最后，我们发现，对于给定的莱茵河波数，超过分层的喷射比射流比降低分层更接近。
Surface buoyancy gradients over a quasigeostrophic fluid permit the existence of surface-trapped Rossby waves. The interplay of these Rossby waves with surface quasigeostrophic turbulence results in latitudinally inhomogeneous mixing that, under certain conditions, culminates in a surface buoyancy staircase: a meridional buoyancy profile consisting of mixed-zones punctuated by sharp buoyancy gradients, with eastward jets centred at the sharp gradients and weaker westward flows in between. In this article, we investigate the emergence of this buoyancy staircase limit in surface quasigeostrophic turbulence and we examine the dependence of the resulting dynamics on the vertical stratification. Over decreasing stratification [$\mathrm{d}N(z)/\mathrm{d}z\leq0$, where $N(z)$ is the buoyancy frequency], we obtain flows with a longer interaction range (than in uniform stratification) and highly dispersive Rossby waves. In the staircase limit, we find straight jets that are perturbed by eastward propagating along jet waves, similar to two-dimensional barotropic $β$-plane turbulence. In contrast, over increasing stratification [$\mathrm{d}N(z)/\mathrm{d}z\geq0$], we obtain flows with shorter interaction range and weakly dispersive Rossby waves. In the staircase limit, we find sinuous jets with large latitudinal meanders whose shape evolves in time due to the westward propagation of weakly dispersive along jet waves. These along jet waves have larger amplitudes over increasing stratification than over decreasing stratification, and, as a result, the ratio of domain-averaged zonal to meridional speeds is two to three times smaller over increasing stratification than over decreasing stratification. Finally, we find that, for a given Rhines wavenumber, jets over increasing stratification are closer together than jets over decreasing stratification.
