Dependence of the variation coefficient of nautical radar image sequences on the grazing and azimuth angle and consequences for the calibration

摘要

The significant wave height can be determined over the SNR. The SNR is inversely proportional to the square of the variation coefficient. For the improvement of the calibration of the measuring system the dependence of the variation coefficient on the grazing and azimuth angle is investigated in this paper. It is shown that the variation coefficient grows with shrinking grazing angle. Additionally it has an azimuthal dependence with greater values in downwind and smaller values in upwind direction. For the calibration the distance of the choosen Cartesian area to the antenna and the azimuth angle has to be taken into account. This has to be analysed with a dataset of complete polar radar image sequences including parallely taken wave data gained for example with a wave rider bouy.