Polarimetric radiometer configurations: potential accuracy and sensitivity

Ocean wind speed and direction can be assessed with a polarimetric radiometer system measuring the full set of Stokes parameters. There are two fundamentally different ways of implementing the polarimetric radiometer system: polarization combining and correlation radiometer systems. Also, within each fundamental category there are significant tradeoffs. This paper discusses the different implementation possibilities. Paramount issues are potential instrument stability and sensitivity as well as the tradeoff between increased microwave hardware complexity and fast digital correlator circuitry. It is concluded that each implementation has its role to play, but for a given application the choice of system configuration is important. Following these considerations, a second-generation airborne, imaging, polarimetric radiometer system, used by the authors for ocean wind vector sensing, is described and discussed.