Polar Mesospheric Clouds and Their Atmospheric Environment

本提案下的研究活动将包括理论建模和数据分析相结合。它的主要目标是进一步了解位于50至100公里高度之间的大气区域的能量学和动力学。它将包括对极地中间层云（PMC）的深入研究，PMC是夏季极地中间层顶区域在84公里高度附近的能量学和动力学的突出表现。我们先前开发的用于模拟PMC演化和光学性质的新建模技术将与该大气区域的热和成分结构的现有动态光化学模型相结合。新获得的大气特性卫星测量数据将用于开发该地区热、动力和输送过程的诊断模型。第二个目标将是确定低层大气化学成分的长期人为变化对该区域的热力和动力结构的影响程度。特别是，我们将开发经验和第一性原理建模方法来支持我们最近的假设，即PMC是一个相对较新的现象，是对流层甲烷水平上升的间接结果。

The research activity under this proposal will consist of a combination of theoretical modeling and data analysis. Its primary objective is to gain an increased understanding of the energetics and dynamics of the atmospheric region situated between heights of 50 and 100 km. It will consist of an indepth study of Polar Mesospheric Clouds (PMC), a phenomenon which is a prominent manifestation of the energetics and dynamics in the summertime polar mesopause region near 84 km height. New modeling techniques which we have previously developed for simulating PMC evolution and optical properties will be combined with existing dynamical-photochemical models for the thermal and compositional structure of this atmospheric region. Newly- available satellite measurements of atmospheric properties will be used to develop a diagnostic model of the region's thermal, dynamical and transport processes. A second objective will be to determine the extent to which long-term anthropogenic changes in chemical composition of the lower atmosphere has impacted the thermal and dynamical structure of this region. In particular, we will develop both empirical and first-principles modeling methods to support our recent hypothesis that PMC is a relatively recent phenomenon, an indirect result of rising levels of tropospheric methane.