The author puts forward the layer-by-layer inversion method for one-dimensional wave problem, which is based on the gradient regularization(GR)method for wave equation inversion.

本文在求解波动方程反问题的GR（梯度正则化法）方法基础上提出一种一维波动问题的分层反演方法。

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"An inversion layer is keeping the smoke close to the ground, limiting visibility and reducing helicopter air operations, " Berry said.

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The cold waters mean a large temperature contrast between the land and ocean -- conditions that favor the formation of a strong inversion layer that traps smog over cities, such as the Los Angeles, Calif.

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