双线偏振天气雷达零滞后相关系数在临近预报中的应用

Application of zero lag correlation coefficient of dual polarization weather radar in nowcasting

零滞后相关系数作为双线偏振天气雷达特有的一种偏振参量,已开始在短临天气预报和灾害性天气预警中发挥明显作用。为研究零滞后相关系数参量在典型天气过程中的变化特征,利用双偏振雷达相关系数识别非降水回波、降水回波、融化层及冰雹,阐述了相关系数产品在短临天气预报中的应用。结果表明,相比传统单偏振天气雷达,双偏振雷达零滞后相关系数识别回波类型更为直观和准确,可以直接有效地对云中的冰雹区进行判断,且高仰角相关系数产品更能识别出融化层。另一方面,在电磁波穿过连续强回波时,还存在相关系数被衰减,以及在弱信噪比时产品质量下降等局限性,应在实际应用中加以区分。研究为将来双偏振天气雷达在短临天气预报业务中的应用提出了可参考性指标。

As a peculiar polarization parameter to dual polarization radar, correlation coefficient has begun to play an important role in short-term and disastrous weather forecasting. To study the variation characteristics of zero-lag correlation coefficient parameters in typical weather processes, the correlation coefficient of dual polarization radar is used to identify non-precipitation echoes and precipitation echoes, melting layer and hail. The application of correlation coefficient products in nowcasting is expounded. The results show that compared with the traditional single polarization weather radar, the correlation coefficient is more intuitive and accurate in identifying the echo type. It can directly and effectively judge the hail area in clouds, and can better reflect the melting layer with high elevation. On the other hand, the correlation coefficient also has some limitations, such as the attenuation of electromagnetic wave through the continuous strong echo and the degradation of product quality when the signal-to-noise ratio is weak. It should be distinguished in practical application, and a reference index is proposed for the future application of dual polarization weather radar in nowcasting.