Detection, Imaging and Characterisation of Fog Fields by Radar

As a significant phenomenon in meteorology, fog has attracted more and more concern from the scientific community, because of its impacts on visibility in air- and road-transportation. E.g., at airports, the frequency of aircrafts taking off and landing has to be reduced during heavy fogs, because in conditions of low visibility the pilots need to have more space between the aircrafts during landing and taxying. In this context, many approaches have been proposed to detect fog with various types of instruments. Among the active remote sensing instruments, radars are well suited for continuous fog observations, and they can satisfy the need for high spatial resolution and sensitivity. Compared to traditional centimeter-wave radars, millimeter-wave radars are more sensitive to minute fog droplets, whereas the gaseous attenuation from oxygen and water vapor is still very small. The trade-off is that the attenuation from fog droplets at millimeter waves is much larger than at centimeter waves. In this thesis, we study the observation of fog with millimeter-wave radars and investigate the feasibility of developing an advanced fog-visibility radar.