Abstract

Helioseismology has revealed an increase in the rotation rate with depth in a thin (\({\sim}30\) Mm) near-surface layer. The normalized rotational shear in this layer does not depend on latitude. This rotational state is shown to be a consequence of the short characteristic time of near-surface convection compared to the rotation period and radial anisotropy of convective turbulence. Analytical calculations within mean-field hydrodynamics reproduce the observed normalized rotational shear and are consistent with numerical experiments on radiative hydrodynamics of solar convection. The near-surface shear layer is the source of global meridional flow important for the solar dynamo.

中文翻译：

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太阳自转近地表剪切层的起源

摘要

日震学揭示了近地表薄层（ \({\sim}30\) Mm）的旋转速率随着深度的增加而增加。该层中的归一化旋转切变不取决于纬度。与对流湍流的旋转周期和径向各向异性相比，这种旋转状态被证明是近地表对流特征时间短的结果。平均场流体动力学中的分析计算再现了观察到的归一化旋转剪切，并且与太阳对流辐射流体动力学的数值实验一致。近地表剪切层是对太阳发电机很重要的全球经向流的来源。