Evaluating the Algorithm for Correction of the Bright Band Effects in QPEs with S-, C-and X-Band Dual-Polarized Radars

The bright band, a layer of enhanced radar reflectivity associated with melting ice particles, is a major source of significant overestimation in quantitative precipitation estimation(QPE) based on the Z–R(reflectivity factor–rain rate) relationship.The effects of the bright band on radar-based QPE can be eliminated by vertical profile of reflectivity(VPR) correction. In this study, we applied bright-band correction algorithms to evaluate three different bands(S-, C-and X-band) of dual-polarized radars and to reduce overestimation errors in Z–R relationship–based QPEs. After the reflectivity was corrected by the algorithms using average VPR(AVPR) alone and a combination of average VPR and the vertical profile of the copolar correlation coefficient(AVPR+CC), the QPEs were derived. The bright-band correction and resulting QPEs were evaluated in eight precipitation events by comparing to the uncorrected reflectivity and rain-gauge observations, separately. The overestimation of Z–R relationship–based QPEs associated with the bright band was reduced after correction by the two schemes for which hourly rainfall was less than 5 mm. For the verification metrics of RMSE(root-mean-square error), RMAE(relative mean absolute error) and RMB(relative mean bias) of QPEs, averaged over all eight cases, the AVPR method improved from 2.28,0.94 and 0.78 to 1.55, 0.60 and 0.40, respectively, while the AVPR+CC method improved to 1.44, 0.55 and 0.30, respectively.The QPEs after AVPR+CC correction had less overestimation than those after AVPR correction, and similar conclusions were drawn for all three different bands of dual-polarized radars.     

新一代天气雷达

阐述了双偏振多普勒雷达的理论基础，以ＣＳＵ－ＣＨＩＬＬ Ｓ波段双偏振及多普勒天气雷达为例，介绍了双偏振多普勒雷达的系统结构和工作原理，并以雷达测量的数据处理和分析实例说明了双偏振多普勒雷达在气象学中的应用。