Abstract. We used a nonlinear mechanistic global circulation model to analyze the migrating quarterdiurnal tide (QDT) in the middle atmosphere with focus on its possible forcing mechanisms: the absorption of solar radiation by ozone and water vapor, nonlinear tidal interactions, and gravity wave–tide interactions. We show a climatology of the QDT amplitudes, and we examine the contribution of the different forcing mechanisms to the QDT amplitude. To this end, we first extracted the QDT from the model tendency terms and then removed the respective QDT contribution from the different tendency terms. We find that the solar forcing mechanism is the most important one for the QDT; however, the nonlinear and gravity wave forcing mechanisms also play a role in autumn and winter, particularly at lower and middle latitudes in the mesosphere and lower thermosphere. Furthermore, destructive interference between the individual forcing mechanisms is observed. Therefore, tidal amplitudes become even larger in simulations with the nonlinear or gravity wave forcing mechanisms removed.

中文翻译：

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季潮迁移的强迫机制

摘要。我们使用非线性机械全球环流模型分析了大气中部迁移的四分之一日潮 (QDT)，重点关注其可能的强迫机制：臭氧和水蒸气对太阳辐射的吸收、非线性潮汐相互作用和重力波-潮汐相互作用. 我们展示了 QDT 振幅的气候学，并检查了不同强迫机制对 QDT 振幅的贡献。为此，我们首先从模型趋势项中提取 QDT，然后从不同的趋势项中去除各自的 QDT 贡献。我们发现太阳强迫机制是 QDT 最重要的机制；然而，非线性和重力波强迫机制也在秋冬季起作用，特别是在中层和低热层的低纬度和中纬度地区。此外，观察到各个强迫机制之间的破坏性干扰。因此，在去除非线性或重力波强迫机制的模拟中，潮汐振幅变得更大。