CEDAR: Ground-Based Optical Imaging of Sporadic Sodium Clouds Near the Summer Mesopause, Using Resonantly Scattered Sunlight

研究人员将开发一种新的方法来获取零星的中层钠云的二维图像。这些图像将由来自钠激光雷达和光学光谱仪的数据组合而成，这些数据来自北极夏季的几个月。该项目包括对阿拉斯加Poker Flat的现有仪器进行微小修改，以及开发分析和校准软件，以高可靠性地执行二维成像。中层顶区有中性和电离的金属原子层，这些原子层通过流星的消融来补充。这些金属层可用作中层顶附近的热、化学和动力条件的示踪剂。虽然已经使用各种技术研究了这些层的高度分布，但这些层的水平结构仍然未知。这项研究的目的是利用太阳照射钠原子，并使用灵敏的仪器探测散射的阳光，来观察金属层的二维结构。同时进行的激光雷达测量将提供有关各层高度分布的信息。各种模式表明，中层顶的温度结构可能是全球变化的敏感指标。了解中间层中零星的层的分布对于研究加热和冷却中间大气的过程很重要。

The investigators will develop a new method to obtain two-dimensional images of sporadic clouds of mesospheric sodium. These images will be constructed by combining data from a sodium lidar and an optical spectrometer obtained during arctic summer months. The project involves minor modifications to existing instruments at Poker Flat, Alaska, and the development of analysis and calibration software to perform the two-dimensional imaging with high reliability. The mesopause region hosts persistent layers of neutral and ionized metallic atoms that are replenished by the ablation of meteors. These metal layers can be used as tracers of the thermal, chemical, and dynamical conditions near the mesopause. Although the altitude distribution of these layers have been studied using various techniques, the horizontal structure of the layers remains unknown. This investigation aims to observe the two-dimensional structure of metallic layers using the sun to illuminate sodium atoms, and sensitive instrumentation to detect the scattered sunlight. The simultaneous lidar measurements will provide information about the altitude distribution of the layers. Various models have shown that the temperature structure in the mesopause may be a sensitive indicator of global change. Understanding the distribution of sporadic layers in the mesosphere is important in studying processes that heat and cool the middle atmosphere.