Abstract:

In order to make an acquaintance about application of the C-band weather radar data in  heavy rainfall processes, Tianshui Doppler radar data was used to research different radar echoes characteristics. A low-quality heart echo precipitation process occurring on July 8, 2013 and a high-quality heart echo precipitation process on August 1, 2013 in Tianshui of Gansu were selected as rainfall processes example. Firstly, based on the consideration of radar system bias, the precipitation was estimated quantificationally by the weather radar. Secondly, the relationship of derived winds, echoes and precipitation during the two rainfall processes were compared, and the echoes were extrapolated according to the water content conservation equation,  the derived winds and reflectivity were used to examine the early warning condition for hail and short time heavy rain occurrence. The result of radar quantitative precipitation estimation showed that the different Z-I relationship for different type precipitation was obviously superior to the default Z-I relationship, and due to signal attenuation of radar echoes, it was needed to revise observed echo before using it. A comparison between the derived winds, echoes and the precipitation of these two processes showed that there was a good agreement between the echo intensity and the precipitation area.For the low-quality heart echo precipitation, the position of the observed and extrapolated echoes was coincident, but the intensity of the extrapolated echo was stronger. For the high-quality heart echo precipitation process,  the extrapolated echo was slower than the observed echo. After considering radar system calibration, some characteristic relations of hail and flash heavy rain conformed to the warning conditions.

Key words: heavy precipitation, radar, retrieval, quantitative precipitation estimation, forecasting and warning

摘要：

利用甘肃省天水市C波段多普勒雷达资料，选取2013年7月8日和8月1日2次强降水过程，在考虑雷达系统标定偏差的基础上用雷达定量估计降水，对比2次降水过程的雷达反演风场、回波与降水之间的关系，并利用雨水含量守恒方程对回波进行外推，利用反演结果检验发生冰雹和大风等强对流天气过程的预警条件。结果表明：不同降水类型采用不同Z-I关系估计的降水效果明显优于雷达默认的Z-I关系，并且由于C波段雷达回波信号的衰减，在使用前需对观测回波进行衰减订正；2013年7月8日的降水过程为低质心回波降水过程，2013年8月1日的降水过程为高质心回波降水过程，2次降水过程的回波强度与降水范围有很好的对应；对于低质心回波降水过程，外推回波与观测回波位置较为吻合，但强度偏强。对于高质心回波降水过程，外推回波较观测回波位置偏后，且强度偏强；考虑雷达系统标定偏差后，冰雹和短时强降水对应的一些特征量关系符合相关预警条件。

关键词: 强降水, 雷达, 反演, 定量降水估计, 预报预警