The compressional beta effect: A source of zonal winds in planets?
The compressional beta effect: A source of zonal winds in planets?
复制标题
压缩贝塔效应：行星中纬向风的来源？
DOI：
10.1016/j.icarus.2014.04.019
复制
发表时间：
2014
期刊：
影响因子：
3.2
通讯作者：
Stellmach
中科院分区：
文献类型：
--
作者：
Verhoeven;Stellmach
木星和土星等巨型行星的表面具有强烈的纬向风模式。尽管在过去几十年中已经提出了几种可能驱动这些喷流的不同机制，但纬向风的起源仍不清楚。在这里，我们探索了行星自转与对流流体的压缩和膨胀的相互作用可以通过压缩莱茵式机制驱动多个深层纬向喷流的可能性，正如 Ingersoll 和 Pollard 最初提出的那样（Ingersoll, AP, Pollard, D.[1982]. Icarus 52 (1), 62–80）。在一定限度内，这种深层机制在数学上类似于可能在云层运行的经典莱茵河机制。预测喷流发生在压缩莱茵河长度 l R=(2 Ω< H ρ-1> v jet-1)-1/2，其中 Ω 是角速度，< H ρ-1> 是平均反密度标度高度，v jet 是典型喷流速度。使用滞弹性近似的二维数值模拟表明，该机制能够稳健地生成预测宽度的射流，并且它通常主导比 O (l R) 更深的系统中的动力学。据观察，位涡阶梯是自发形成的，并且通常伴随着不稳定的分层浮力阶梯。该机构仅在大旋转速率下运行，超过了球壳中深度对流的三维模拟中通常达到的旋转速率。应用于木星和土星时，压缩的莱茵河尺度合理地符合现有的观测结果。有趣的是，即使是微弱的垂直密度变化，例如地核中的垂直密度变化，也可能产生大量喷流，从而导致流动结构与通常在这种情况下使用的 Boussinesq 模型预测的完全不同。
Giant planets like Jupiter and Saturn feature strong zonal wind patterns on their surfaces. Although several different mechanisms that may drive these jets have been proposed over the last decades, the origin of the zonal winds is still unclear. Here, we explore the possibility that the interplay of planetary rotation with the compression and expansion of the convecting fluid can drive multiple deep zonal jets by a compressional Rhines-type mechanism, as originally proposed by Ingersoll and Pollard (Ingersoll, AP, Pollard, D.[1982]. Icarus 52 (1), 62–80). In a certain limit, this deep mechanism is shown to be mathematically analogous to the classical Rhines mechanism possibly operating at cloud level. Jets are predicted to occur on a compressional Rhines length l R=(2 Ω< H ρ-1> v jet-1)-1/2, where Ω is the angular velocity,< H ρ-1> is the mean inverse density scale height and v jet is the typical jet velocity. Two-dimensional numerical simulations using the anelastic approximation reveal that this mechanism robustly generates jets of the predicted width, and that it typically dominates the dynamics in systems deeper than O (l R). Potential vorticity staircases are observed to form spontaneously and are typically accompanied by unstably stratified buoyancy staircases. The mechanism only operates at large rotation rates, exceeding those typically reached in three-dimensional simulations of deep convection in spherical shells. Applied to Jupiter and Saturn, the compressional Rhines scaling reasonably fits the available observations. Interestingly, even weak vertical density variations such as those in the Earth core can give rise to a large number of jets, leading to fundamentally different flow structures than predicted by the Boussinesq models typically used in this context.
登录
查看更多内容
影响因子：
4.6
作者：
W. Park
通讯作者：
W. Park
由上表面纬向喷流驱动的发电机：在巨行星上的应用
影响因子：
3.2
作者：
C. Guervilly;P. Cardin;N. Schaeffer
通讯作者：
N. Schaeffer
巨行星中纬向喷流与发电机作用之间的关系
影响因子：
5.2
作者：
M. Heimpel;Natalia Gómez Pérez
通讯作者：
Natalia Gómez Pérez
土星云层的纬向风
影响因子：
3.2
作者：
A. Sánchez‐Lavega;J. F. Rojas;P. Sada
通讯作者：
P. Sada
快速旋转球壳中与时间相关的 β 对流
影响因子：
4.6
作者：
V. Morin;E. Dormy
通讯作者：
E. Dormy