310 / 2023-10-12 21:54:58

Analysis of a heavy rainstorm process in Henan, China based on multi-source data

heavy rainstorm,GNSS,precipitable water vapor,ERA5,Henan

In July 2021, a heavy rainstorm was sweeping across Henan Province, causing geological disasters such as floods, mudslides, and landslides, which seriously threatened the safety of human life and property. Since precipitable water vapor (PWV) is related to the occurrence and scale of rainfall, so it is greatly significant to study the occurrence process of extremely heavy rain using PWV for early warning. Here based on Global Navigation Satellite System (GNSS) observation and its meteorological file, ERA5 reanalysis data, and weather station data, the relationship between PWV and rainfall was studied. The results show that the average RMSE of air temperature and pressure from GNSS meteorological files are 1.794℃ and 1.71hPa, respectively. During the week before the heavy rain, the temperature drops remarkably and the temperature difference decreases, while the relative humidity increases and the relative humidity difference decreases. Different from the normal rainfall, we found that the PWV variation in Henan rainstorm has a special "charge" period. During the period of heavy rain, ZHNZ station located in the worst-hit area received external PWV transport at a speed of 6.2 times/6h. We also find that the peak rainfall of HAHB station lags one day behind that of ZHNZ station, as well as the maximum of PWV defers one day behind. In this study, the characterization of PWV and meteorological factors during heavy rain are revealed, which could provide a theoretical basis for heavy rain early warning with GNSS and its attached meteorological file in the future.