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/低热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。重点将是太阳变化对50公里以上总信号的贡献，由大气平均流量和太阳强迫的变化介导。分析的基础将是不同季节和各种太阳条件下的一般环流模式积分，将借助从对流层到中间层和热层的潮汐传播的线性模型进行解释和说明。主要的问题将是太阳效应在多大程度上是由纬向平均风、行星波活动、直接热强迫或重力波活动的相关变化引起的。对于后者，将投入特别的努力来改进在稳定的平均大气流量和温度以及潮汐传播的总背景下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.