基于实时精密单点定位技术的暴雨短临预报

Abstract

提出了一种将实时精密单点定位(Precise Point Positioning,PPP) 技术用于暴雨短临预报的新方法.该方法首先基于GPS连续运行参考站网 (Continuously Operating Reference Stations,CORS) 实时估计的精密卫星钟差完成PPP解算,再以实时获取的对流层延迟(Zenith Tropospheric Delay,ZTD) 及其增量变化为依据进行暴雨短临预报.研究结果表明:一般雷暴天气来临之前的2～6h,ZTD增量表现为先后突破±5mm/5min,且后续记录到的实际降水量大小与ZTD维持在高水平阶段的时间长短有较好的对应关系;就热带气旋而言,在强风作用下,ZTD增量变化表现的异常活跃和复杂,规律性较弱,但对短临预报强降雨仍有一定的指示作用. A new method was proposed for the rainstorm nowcasting based on GPS Real-Time Precise Point Positioning(RT-PPP) technology.Firstly,GPS un-differenced observations of Continuously Operating Reference Stations(CORS) were used to estimate real-time precise satellite clock biases(SCB).Secondly,based on IGU orbit and real-time estimated SCBs,the real-time Zenith Tropospheric Delay(ZTD) and their increments were obtained by using the RT-PPP.Lastly,real-time ZTD and their increments were used for the rainstorms nowcasting.The numerical results show that ZTD increments exceed ±5 mm/5 min several times before the advent of rainstorms 2～6 h,and the subsequent precipitations have a good relationship with the time length of ZTD maintaining at high levels.As to the tropical cyclone,the ZTD increments are too active and complex to show good regularity because of the action of strong wind.But,there are still some indications to the short-term forecasting of heavy rainfalls caused by tropical cyclone.