Solar contribution to the variability of middle atmosphere solar tides in their interaction with zonal-mean-flow variations, planetary waves and gravity waves

拟议项目的目的是彻底了解在不同时间尺度上控制中间层/热层下层太阳潮汐变化的机制，特别是通过它们对下面大气层变化的反应。重点将放在太阳变率对50公里以上总信号的贡献，这是由大气平均气流和太阳强迫的变化所调节的。分析的基础将是不同季节和不同太阳条件的一般环流模式(GCM)积分，这将借助一个从对流层到中间层和热层的潮汐传播线性模式来解释和解释。主要问题将是纬向平均风、行星波活动、直接热力强迫或重力波活动的相关变化在多大程度上造成了太阳效应。对于后者，将特别致力于改进在稳定的平均大气气流和温度以及潮汐传播的总背景下对重力波传播和破裂的描述。

The purpose of the proposed project is a thorough understanding of the mechanisms controlling the variability of solar tides in the mesosphere/lower thermosphere (MLT) on different time scales, especially via their response to variability in the atmospheric layers below. A focus will be on the contribution of solar variability to the total signal above 50 km, mediated by variations in the atmospheric mean flow and in the solar forcing. Basis of the analyzes will be general-circulation-model (GCM) integrations for different seasons and various solar conditions, which shall be interpreted and explained with the help of a linear model for tidal propagation from the troposphere into the mesosphere and thermosphere. Major questions will be how much a solar effect is caused by related variations in the zonal-mean winds, planetary wave activity, direct thermal forcing, or gravity-wave activity. For the latter a special effort will be invested in an improvement of the description of gravity-wave propagation and breaking in the total background of steady mean atmospheric flow and temperature, and propagating tides.