Solar variability and trend effects in layers and trace gases in the upper atmosphere (SOLEIL)

夏季中极纬地区的中间层中存在着不同的层，这些层的存在归因于水冰颗粒的存在。这些层被称为夜光云(NLC)、极地中球云(PMC)和极地中间层夏季回波(PMSE)，它们反映了不同的观测几何或涉及的完全不同的物理过程。这些层对温度非常敏感(对H2O的敏感性较小)，因此最适合显示长期和太阳周期的变化。实际上，不同层参数(出现频率、层亮度等)在十年时间尺度上的变化。已经从地面和卫星观测中得到报告。然而，其中涉及的物理和光化学过程尚不清楚，一些观察结果与预期相矛盾。在这个方案中，我们想要研究极地夏季中层顶区的长期(十年尺度)层的形成，特别是它们对太阳强迫和温室气体人为增加引起的背景条件变化的敏感性。我们调查和补充了对层(NLC/PMC/PMSE)和痕量气体(地面微波和卫星观测H2O)的现有观测，并用LIMA GCM模式进行了模式计算。在SPP的第三阶段，我们想要特别研究大气中冰形成的反馈机制(例如，通过冷冻干燥)以及上下的耦合机制。

Various layers exist in the summer mesosphere at middle and polar latitudes which owe their existence to water ice particles. These layers are called ‚noctilucent clouds' (NLC), ‚polar meso- sphere clouds' (PMC), and ‚polar mesosphere summer echoes' (PMSE) which reflects different observation geometry or entirely different physical processes involved. These layers are very sen- sitive to temperature (and to a lesser extent to H2O) and are therefore best suited to indicate long term and solar cycle changes. Indeed, variations on decadal time scales of different layer parameters (occurrence frequency, layer brightness etc.) have been reported from ground and satellite based observations. However, the physical and photo-chemical processes involved are not understood and some of the observations contradict expectations. In this proposal we want to study the long term (decadal scale) formation of layers in the polar summer mesopause region, in particular their sensitivity to variations of background conditions caused by solar forcing and anthropogenic increase of greenhouse gases. We investigate and complement the available observations on layers (NLC/PMC/PMSE) and trace gases (ground based microwave and satellite observations of H2O) and perform model calculations with the LIMA GCM model. In the third phase of the SPP we want to study in particular the feed back mechanisms of ice formation on the atmosphere (e. g., through freeze drying) and the coupling mechanisms to above and below.