Abstract The dissipation of acoustic–gravity waves in the thermosphere due to molecular viscosity and thermal conductivity based on a modified system of hydrodynamic equations is studied. A modification of the system of equations consists in additional taking into account in the linearized Navier–Stokes equations and heat transfer additional terms describing the transfer of momentum and energy due to the background density gradient, except for the usually taken into account velocity gradient. Using these modified equations, the local dispersion equation of acoustic–gravity waves in an isothermal dissipative atmosphere is obtained. On this basis, new general expressions for the attenuation rates in time and in space for both acoustic and gravity waves in the entire spectral range are derived in the paper. The relationship between the rates of AGW temporal and spatial attenuation is analyzed. The results obtained are consistent with satellite-based observations of AGW at the heights of the thermosphere, indicating filtering of the wave spectrum due to viscosity and thermal conductivity.

中文翻译：

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地球热层中声引力波的耗散

摘要 基于流体动力学方程的修正系统，研究了由于分子粘度和热导率引起的热层中声重力波的耗散。方程组的修改包括额外考虑线性纳维-斯托克斯方程和热传递附加项，描述由于背景密度梯度引起的动量和能量转移，除了通常考虑的速度梯度。使用这些修正方程，可以得到等温耗散大气中声-重力波的局部色散方程。在此基础上，本文推导了声波和重力波在整个光谱范围内的时间和空间衰减率的新通用表达式。分析了AGW时空衰减率之间的关系。获得的结果与基于卫星的热层高度处的 AGW 观测结果一致，表明由于粘性和导热性对波谱进行了过滤。