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。我的研究推进了我们对中间层和低热层（MLT，~50 - 150 km）的了解，这是地球大气中一个鲜为人知但令人着迷的区域。它是低层/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影响）之间的缓冲。这个区域吸收与向上运动的波（潮汐，重力波和行星波）相关的能量和动量，并将在较高高度吸收的大部分太阳能辐射到太空。我们已经开发出了非常灵敏的光学仪器，可以观察80至100公里范围内自然产生的辐射波长的微小变化（~10（-14）m）（夜光），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要准确和快速，并将用于研究MLT动力学的细节，这在以前是不可能的。计划扩展到白天观测、极光和风洞等应用。我们的一个测风仪器位于极地环境大气研究实验室（尤里卡，80 N），与其他仪器一起，正在研究极地MLT的性质。我们计划在其他MLT观测站安装我们的其他仪器，以扩大这些调查。为了加强我们的地面观测，将分析卫星观测和复杂的全球大气环流模式，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（风振幅超过150公里/小时）和重力波，以及原子氧（夜光的组成部分）的分布。结合本地和全球的观点是确定重要的MLT过程的关键。

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.