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

在中纬度和极纬度的夏季中间层中存在着各种各样的层，它们的存在是由于水冰颗粒。这些层被称为“夜光云”（NLC）、“极中层云”（PMC）和“极中层夏季回波”（PMSE），它们反映了不同的观测几何或完全不同的物理过程。这些层对温度非常敏感（在较小程度上对水也很敏感），因此最适合用于指示长期和太阳周期的变化。实际上，已经从地面和卫星观测报告了不同层参数（发生频率、层亮度等）在年代际时间尺度上的变化。然而，所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。在这一建议中，我们希望研究极地夏季中层区域的长期（年代际尺度）层的形成，特别是它们对太阳强迫和人为温室气体增加引起的背景条件变化的敏感性。我们调查和补充了现有的地层观测（NLC/PMC/PMSE）和微量气体观测（地面微波和卫星对H2O的观测），并使用LIMA GCM模型进行了模型计算。在SPP的第三阶段，我们希望特别研究冰在大气中形成的反馈机制（例如，通过冷冻干燥）以及与上面和下面的耦合机制。

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.