Latitudinal shear instability in the solar tachocline
Latitudinal shear instability in the solar tachocline
复制标题
太阳速斜层的纬度剪切不稳定性
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
P. Garaud
中科院分区：
文献类型：
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作者：
P. Garaud
为了解释在太阳辐射区和速跃层观测到的自转廓线，Spiegel & Zahn提出了一个基于各向异性湍流角动量输运的模型。尽管他们的模型在再现太阳速跃层的某些特征方面非常成功，但在未经验证的情况下，他们假设湍流的起源可能是由纬向剪切不稳定性引起的。本文研究了二维剪切不稳定性的弱非线性演化，其中全球旋转廓线与雷诺应力之间的相互作用可以自洽地描述。只要初始的旋转配置文件是足够接近边际稳定（这是太阳速跃层的情况下），不稳定性饱和，并放松到一个边缘稳定的状态，这与所观察到的旋转配置文件非常小。因此，这是可能的，速跃层是在相对于纬向剪切不稳定的边缘稳定的状态，并表明，在速跃层的角动量输送是不太可能引起的剪切诱导湍流。
In an attempt to explain the observed rotation profile in the solar radiative zone and the tachocline, Spiegel & Zahn proposed a model based on anisotropic turbulent angular momentum transport. Although very successful in reproducing some of the features of the solar tachocline, their model assumes without verification that the origin of the turbulence could be caused by latitudinal shear instability. This paper studies the weakly non-linear evolution of two-dimensional shear instability, in which the interaction between the global rotation profile and the Reynolds stresses can be described self-consistently. Provided that the initial rotation profile is sufficiently close to marginal stability (which is the case of the solar tachocline), the instability is shown to saturate and to relax to a marginally stable state, which differs very little from the observed rotation profile. It is therefore likely that the tachocline is in a state of marginal stability with respect to latitudinal shear instability, and shows that angular momentum transport in the tachocline is unlikely to be caused by shear-induced turbulence.