이중편파레이더를 이용한 밝은 띠 연구

Abstract

A bright band means that the intensity of radar echo is more exaggeratedly displayed than the real amount of rain due to the permittivity difference of raindrop at the altitude under the layer of 0℃(melting layer). Echo intensity is used in forecasting the amount of precipitation by using a weather radar. When a bright band appears, which means that a more exaggerated echo appears, the value of the forecast amount of precipitation is exaggeratedly estimated than a real one. But as the amount of precipitation is zero or less than 1.0mm in the regions where the bright band does show up, the error of forecast takes place. This research sought to find a new method to distinguish between bright bands by making use of the radar image materials of the duel polarization radar installed at the weather radar research center. The analysis method was to select the cases where bright bands showed up(on November 1, 7, and 8, 2009) and analyze them by using the ZDR, RHOHV, KDP, and PID images of the duel polarization radar. In analyzing the cases, it was difficult to make a clear distinction of the altitudes on which bright bands appeared on the ZDR image, and the scope with a negative(-) value showed up on the very upper altitude of the altitude on which bright bands appeared. In the RHOHV image, while the correlation coefficient was close to 1 in the peripheral area, the correlation coefficient was lower on the altitude on which bright bands appeared. In the KDP image, its value of the altitude on which bright bands appeared was higher in comparison with that of other altitudes, and the value with the negative(-) value turned up on the upper and lower altitude of the altitude on which bright bands appeared in both altitudes. Finally, in the PID image, the type of raindrop consisting of the altitudes on which bright bands appeared turned up as a form of grain, small hail, and hail. Of all the image materials used in the analysis work, bright bands showed clearly up in the RHOHV and KDP image.