Rotating annulus experiments to simulate the air motion in the stratified layer

到目前为止，平流层中的空气运动已经得到了理论和数值模拟的研究。然而，实验室模拟对于研究它们的基本动力学结构也是有用的。本项目的目的是在旋转的流体环空上进行实验，研究斜压气流向上层层流的向上传播，并在平流层产生类似极地涡旋的紧闭涡旋。利用水深13-14 cm的环空，成功地在3 cm以下的下层产生了径向温差作用下的斜压流，并通过加热水面使5 cm以上的上层分层。根据大气动力学中的准地转位涡方程，我们得到了以下两个实验结果：(1)根据大气动力学中的准地转位涡方程，塔流体层中产生的正压波的涡度穿透到层结上层，并随高度呈指数衰减；[包围2]如果层结足够深，则在斜压下层中出现定常的轴对称或波流需要较强的层结(垂直温度梯度)。将结果应用于实际大气，特别是臭氧层吸收紫外线并使空气变暖使平流层变暖的结果，被发现对中纬度大尺度对流层风是必不可少的。[圈内1]的结果被描述在论文中，这篇论文被接受发表在流体实验中。这一结果[圈内1]已在提交给《大气科学杂志》的论文中进行了总结。

The air motions in the stratosphere have been so far studied theoretically and by numerical simulations. Laboratory simulations are, however, also useful to investigate their basic dynamical structures. The purpose of this project is to conduct experiments on a rotating fluid annulus to study the upward propagations of the baroclinic flows into the upper stratified layer and to produce the tightly closed vortex such as the polar one in the stratosphere. Using the annulus whose water depth is 13-14 cm, we have succeeded in producing the baroclinic flows in the lower layer imposed the radial temperature difference below 3 cm and making the upper layer above 5 cm stratified by heating the water surface. In this research project, Grant-IN-Aid far Scientific Research, we have gotten the following two experimental results : 【encircled 1】The vorticities of barodinic waves produced in the tower fluid layer penetrate into the stratified upper layer decaying exponentially with height according to the quasi-geostrophic potential vorticity equation in the atmospheric dynamics ; 【encircled 2】If the stratified layer is sufficiently deep, strong stratification (vertical temperature gradient) is necessary for steady axisymmetric or wave flows to emerge in the baroclinic lower layer. Applying the result 【encircled 1】to the real atmosphere, in particular, that the ozone layer absorbs the ultraviolet light and warm up the air to make the stratosphere is found essential for the mid-latitude large-scale tropospheric winds. The result 【encircled 1】 was described in the paper that was accepted for the publication in Experiments in Fluids. The result 【encircled 1】 has been summarized in the paper submitted to Journal of Atmospheric Sciences.