Techniques For The Automated Observation Of Clouds

This report surveys techniques for cloud detection to assess their suitability for meeting the requirements of the Automated Observation System (AOS). A microwave sensor is essential because of the requirements for observing cloud top heights and documenting multiple cloud layers. Wavelengths between 3 cm and 8.6 mm could be used for this application, and a detailed sensor design study is recommended to evaluate the availability, cost, performance, and reliability of components and systems. Pulsed or continuous-wave radars could meet most of the requirements, although measurements of cloud base with high accuracy at low altitude may be difficult with some pulsed systems. Keywords: Cloud base; Ceilometer; Cloud amount; Automated cloud observation; Remote detection; Ka band radar; X band radar; Lidar.