CEDAR: Continuation to Daytime Potassium Doppler Lidar at Arecibo

这个为期一年的项目旨在完成日间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。 自2001年2月以来，以窄带注入种子翠绿宝石环形激光器为基础的阿雷西博激光雷达已经能够在中间层和低热层区域进行夜间温度和钾密度测量。 通过7年的运行，夜间技术已经成熟，并收集了足够的数据来表征夜间热结构和夜间钾的季节变化。为了提高其测量能力和更好地为高空大气学界服务，2005年提出了一个项目，并获得了为期三年的资金，将阿雷西博激光雷达升级为日间观测能力，并进行广泛的观测，以研究阿雷西博天文台全天周期的热带中层和低热层区域。 激光雷达的改进工作已经进行了三年，但最初打算使用的法拉第滤波器没有达到预期的效果。 以前项目的许多其他技术目标都已实现，如缩小视场、建造法拉第滤波器测试站、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，还获得了构建新型法拉第滤波器所需的光学元件和硬件。 因此，该项目将完成剩余的步骤，以产生一个日光优化的激光雷达，能够在阿雷西博进行全天观测，其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变。

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.