S波段双线偏振雷达K_(DP)参数计算的初步研究

A primary analysis of different algorithms of K_(DP) based on S band dual-polarization Doppler radar

双线偏振多普勒雷达测量参数KDP在定量估测降雨强度和识别降水粒子相态方面都有着很重要的作用。鉴于雷达实测KDP值来源于S波段双线偏振雷达信号处理器(RVP8)的结果,没有具体的计算过程,不便于进行雷达资料预处理和质量控制,探讨了KDP的3种算法,通过实测数据,将雷达信号处理器(RVP8)观测的KDP作为参考值,进行了对比分析。结果表明:最小二乘法误差最小,精度最高;讨论了沿雷达径向,不同平滑距离对最小二乘法KDP计算的影响。同时研究雷达实测KDP与通过Z-R关系计算的降雨强度之间的关系表明5,km的距离长度既能起到足够的平滑作用,又能保持足够的气象信息,不至于影响测量降水效果;KDP与降雨强度之间存在较好的对应关系,在强降雨阶段尤为显著,可以利用KDP来估算反演降雨强度。

The KDP value detected by dual-polarization Doppler radar plays an important role in measuring rainfall and classifying hydrometeor.The KDP value was directly obtained from S band dual-polarization Doppler radar signal processor（RVP8）and its calculation process was not shown on the technical introduction,thus it was unfavourable to pretreatment and quality control of data.Three methods calculating KDP values were summarized.According to the observational data,the KDP values calculated by three methods were compared with those from signal processor（RVP8）.The results indicate that the error of the KDP value calculated by least square method is the minimum among the three methods.The effects of different smoothness distances along the radar radial on the KDP value with least square method are discussed.The relationship between the KDP value detected by radar and precipitation intensity calculated by Z-R relationship is analyzed.It shows that the smoothness distance to 5 km could retain not only the enough smoothness effect but also the enough meteorological information.Moreover,it does not influence the measurement of precipitation.The relationship between the KDP value and precipitation intensity is significant,especially in strong precipitation phase.Thus,the KDP value could be used to estimate precipitation intensity.