Design of MACSIM Cloud Radar for Earth observation Radiation Mission

Based upon results of a pre-phase A study, this paper presents the design of MACSIM Cloud Radar, which is one of the two active instruments of the Radiation Mission. This radar is a 95 or 79 GHz non-scanning instrument which collects echoes reflected by cloud particles. Its main measurement objectives are the altitudes of the cloud top and base with an accuracy of /spl plusmn/250 m and the ice/liquid water content as a function of the altitude of the different cloud layers. As a result of several trade-offs, a nadir looking radar transmitting unmodulated pulses of about 3 /spl mu/s is designed with a primary design objective of improving the sensitivity. In the last section, detection results for a set of typical clouds are summarised which demonstrates the feasibility of a light instrument in compliance with the user requirements.