CEDAR: Continuation to Daytime Potassium Doppler Lidar at Arecibo

这个为期一年的项目旨在完成白天钾多普勒激光雷达的建造，并在阿雷西博天文台测试其运行情况。阿雷西博激光雷达基于窄带注入种子翠绿宝石环激光器，自2001年2月以来一直能够测量中间层和低热层区域的夜间温度和钾密度。经过七年的运行，夜间技术已经成熟，收集到了足够的数据来表征夜间的热结构和夜间钾素的季节变化。为了加强其测量能力并更好地为大气层服务，2005年提出了一个为期三年的项目，以将阿雷西博激光雷达升级为日间观测能力，并在阿雷西博观测站进行广泛观测，以研究热带中间层和低热层区域的全天周期。过去三年一直在进行激光雷达的修改，但最初打算使用的法拉第滤光器并没有像预期的那样发挥作用。实现了先前项目的许多其他技术目标，如缩小视场、建造法拉第滤光片测试站、实施新的接收器光学斩波器、初步观测测试和实施新的数据处理技术。此外，还获得了构建新的法拉第滤光片所需的光学元件和硬件。因此，该项目将完成剩余的步骤，以生产出能够在阿雷西博进行全天候观测的针对日光进行优化的激光雷达，在那里，它与非相干散射雷达的搭配将使各种科学研究成为可能，例如测量潮汐、重力波、绝对大气密度、金属层化学以及零星原子和离子层的演化。

This one-year project aims to complete construction of a daytime potassium Doppler lidar and to test its operation at Arecibo Observatory. The Arecibo lidar, based on a narrowband injection-seeded alexandrite ring laser, has been able to make nighttime temperature and potassium density measurements in the mesosphere and lower thermosphere region since February 2001. Through seven years of operation, the nighttime technology has matured and sufficient data were collected to characterize the nocturnal thermal structure and nocturnal potassium seasonal variations. To enhance its measurement capability and to better serve the aeronomy community, in 2005 a project was proposed and received funding for three years to upgrade the Arecibo lidar to a daytime observing capability and to conduct extensive observations to study the tropical mesosphere and lower thermosphere region over the full-diurnal cycle at the Arecibo Observatory. The lidar modifications have been underway for the past three years but the Faraday filter originally intended to be used did not perform as expected. Many of the other technical goals of the previous project were achieved, such as narrowing of the field-of-view, construction of the Faraday filter test station, implementation of the new receiver optical chopper, initial observational tests, and implementation of new data processing techniques. In addition, the optical elements and hardware necessary to construct a new Faraday filter were acquired. The project will therefore complete the remaining steps to yield a daylight-optimized lidar capable of making full diurnal observations at Arecibo, where its collocation with the incoherent scatter radar will enable a wide variety of scientific studies, such as measurements of tides, gravity waves, absolute atmospheric density, metal layer chemistry, and the evolution of sporadic atom and ion layers.