Precipitable Water Vapor Retrieval for Rainfall Forecasting using BDS-3 PPP-B2b Signal in the Coastal Region of China

Abstract

Currently, rainfall cannot be accurately forecasted due to poor network communication at ocean. The advantage of the BeiDou Global Navigation Satellite System (BDS-3) PPP-B2b signal, which does not rely on network communication to receive data, can provide Precipitable Water Vapor (PWV) retrieval application services for the open seas in eastern China where communication system is difficult. In this study, the data from the stations in the coastal region of China are used to establish a rainfall forecasting method for monitoring the extreme weather on the sea. Firstly, the service performance of the PPP-B2b is explored. Then, based on 17 Chinese coastal stations, the PWV accuracy is evaluated. Finally, based on the analysis of the relationship between PWV and actual rainfall, a threshold rainfall forecasting method based on sliding window is constructed. The experimental results show that: the PWV accuracy varies slightly depending on the geographic location, in which the mean absolute error (MAE) in the North Sea region is the smallest of 2.1mm, the South China Sea region is the largest of 2.60mm, and the East China Sea region is in the middle of the PWV accuracy of 2.48mm; the optimal predictors of the constructed 12-h sliding-window threshold rainfall prediction method are PWV maximum of 49 mm, PWV increase of 5 mm and PWV increase rate of 1.2 mm/h. The prediction results can reach a Critical Success Index (CSI) value of more than 45%, which has high prediction accuracy and applicability to the coastal region of China in the same period.