Observing and Understanding the Dynamics of the Mesosphere and Lower Thermosphere

了解太阳/地球系统是很重要的，这样我们就可以预测和计划未来我们生活的环境的变化。我的研究提高了我们对中间层和低层热层（MLT， ~50 -150公里）的认识，这是地球大气中一个知之甚少但很有吸引力的区域。它在低层/中层大气（一种能够进行多种运动的流体）和近地空间环境（一种电离介质，其运动受到与太阳有关的外部影响的限制和直接强迫）之间起缓冲作用。这个区域吸收与向上移动的波（潮汐、重力波和行星波）相关的能量和动量，并将在较高海拔吸收的大部分太阳能辐射到太空。具体是如何实现的尚不清楚。我们已经开发了非常灵敏的光学仪器，可以观察80到100公里范围内（夜光）自然发射的波长的微小变化（~10(-14)m），以测量风（多普勒效应）。这些变化的测量比世界上任何其他气辉仪器都更准确、更快速，并将用于研究MLT动力学的细节，这在以前是不可能的。计划将其扩展到日间观测、极光和风洞等应用。我们的一种风力仪器位于极地环境大气研究实验室（Eureka, 80N），与其他仪器相结合，正在研究极地MLT的性质。我们计划将我们的其他仪器安置在其他MLT天文台，以扩大这些调查。为了增强我们的地面观测，将分析卫星观测和复杂的全球大气环流模式，将它们与我们的观测进行比较，并用于提供全球背景。我们特别感兴趣的是大气潮汐（风速超过150公里/小时）和重力波，以及氧原子的分布（夜光的组成部分）。结合本地和全球视角对于确定重要的MLT过程至关重要。

Understanding the Sun/Earth system is important so that future changes to the environment that we live in can be predicted and planned for. My research advances our knowledge of the mesosphere and lower thermosphere (MLT, ~50 -150 km), a poorly understood but fascinating region in the Earth's atmosphere. It acts as a buffer between the lower/middle atmosphere (a fluid capable of many types of motion) and the near-Earth Space Environment (an ionized medium whose movement is constrained and directly forced by external influences associated with the Sun). This region absorbs the energy and momentum associated with upward moving waves (tides, gravity waves and planetary waves) forced below and radiates to space much of the Solar energy absorbed at higher altitudes. The details of how this is accomplished are still unclear.We have developed extremely sensitive optical instruments which observe tiny shifts (~10(-14) m) in the wavelengths of naturally occuring emissions in the 80 to 100 km region (nightglow) to measure winds (the Doppler effect). These shifts are measured more accurately and quickly than is possible with any other airglow instrument in the world and will be used to investigate details of the MLT dynamics previously not possible. Expansion to applications such as daytime observations, aurora and wind tunnels is planned. One of our wind instruments is uniquely located at the Polar Environment Atmospheric Research Laboratory (Eureka, 80N) where in combination with other instruments, the nature of the polar MLT is being investigated. We plan to locate our other instruments at other MLT observatories to expand these investigations.To augment our ground based observations, satellite observations and sophisticated global general circulation models will be analysed, compared with our observations and used to provide a global context. Of particular interest to us are atmospheric tides (wind amplitudes over 150 km/hr) and gravity waves, and the distribution of atomic oxygen (the constituent responsible for nightglow). Combining local and global perspectives is essential for identifying the significant MLT processes.