Polarimetric microwave radiometer

a new type of remote sensor

can measure not only the first two Stokes parameters

but also the third and the fourth Stokes parameter of ocean surface radiation. Thus it opens a new field of microwave remote sensing on wind vectors. There is wind direction ambiguity in actually retrieved oceanic wind field using fully polarimetric radiometer data because wind direction signals in Tv and Th are very small comparing with other geophysical parameters

while T3 and T4 are basically two order smaller than those of horizontal and vertical polarization

and meanwhile there are calibration errors in each Stokes parameters. In this paper

we dedicate to improve the calibration accuracy by designing a fully onboard calibrator and reasonably allocating time for calibration and observation during one scan cycle. The theory of polarimetric microwave radiometer calibration is given and the actual considerations of the on-board fully polarimetric calibration standard are demonstrated. An original idea of calibrating polarimetric radiometer on satellite is presented. The relation between scan mode and wind direction retrieval error is analyzed. A new scanning geometry to remove these wind direction ambiguous solutions is devised and modeled. Simulation results show this kind of scanning geometry can remove wind direction ambiguity effectively. The accuracy of wind direction retrieval can be improved to 15°. On the other hand

due to the limited space on satellite

the swath of a single side scan can reach above 760 kilometers.