多普勒天气雷达径向速度产品在预报中的应用

Study on application of radial velocity product of Doppler weather radar to prediction

对江苏南京雷达站四年内降水前多普勒天气雷达径向速度回波及其VWP产品的特征进行了具体的研究。速度回波图的统计结果表明,非降水回波的辐合特征和降水的发生是相关的,对降水过程的发生具有一定的提前量,该预报提前量存在地域差异和季节差异。对VWP产品的统计分析表明,风向随高度顺转且风速随高度增大时,有利于降水系统的维持和发展;同时"ND"厚度和相对湿度在大面积层状云或混合云降水过程中呈反相关,在一定程度上反映了相对湿度的变化,且"ND"厚度的变化对降水的产生也有一定的提前量,对短时预报有指导意义。

In this article the characteristics of the velocity echo images and VWP product before precipitation are deeply analyzed based on the Doppler weather radar in Nanjing, Jiangsu. The statistic resuits of the velocity echo images show that the convergence of the non-precipitation echo is correlative with precipitation, and the appearance of the convergence is ahead of the precipitation, meanwhile, the forecast time fluctuates for different areas and seasons. The statistics of the VWP indicate that it is benefit to maintain and develop the precipitation system when the wind direction turns clockwise and the wind velocity increases with the height; at the same time, ＂ND＂ thickness and relative humidity are anti-correlative under the condition of large scale stratiform cloud precipitation or convective-stratiform mixed cloud precipitation, at a certain extent VWP reflects the relative humidity, then the variation of the ＂ND＂ thickness is also ahead of the precipitation, which gives the instructional significance for forecasting.