Abstract:
The atmospheric precipitable water vapor (PWV) derived from Global Navigation Satellite System (GNSS) provides new data for monitoring meteorological disasters such as heavy rainfall. In this study, we constructed the monthly Precipitation Efficiency (PE) meteorological drought index from a comprehensive perspective of atmospheric water vapor and precipitation, based on daily PWV and precipitation data from five GNSS stations in Hubei Province during 2011-2022. The characteristics and advantages of the index were verified using the Standardized Precipitation Index (SPI), Meteorological Drought Composite Index (MCI), and Standardized Precipitation Evapotranspiration Index (SPEI). The results are as follows. (1) The variation of atmospheric water vapor in Hubei Province has good spatial consistency, while precipitation shows strong local variation characteristics. Among the five GNSS stations, the correlation coefficients of PWV are all greater than 0.98, while the correlation coefficients of rainfall are between 0.66 and 0.90. A combination of the two factors could reflect the comprehensive variations in large-scale PWV and local precipitation during the drought periods. (2) PE index shows strong correlations with SPI, MCI, and SPEI (with correlation coefficients ranging from 0.56 to 0.85), indicating the effectiveness of PE in monitoring drought, but still existing differences in reflecting the severity grades and spatial distributions. (3) The correlation coefficient of PE between GNSS stations (0.50~0.81) is the smallest among the four indexes, indicating that the PE meteorological drought index can reflect the difference in local drought characteristics. Using the PE meteorological drought index to monitor drought events at GNSS stations in Hubei provinces shows that during 2011-2022, the highest frequency of severe drought appeared in Xiangfan, while the drought events in the Wuhan site frequently occurred in the autumn season and lasted a long time. Results confirmed the effectiveness and advantages of the PE drought indices constructed from GNSS PWV in characterizing drought evolution and spatial distribution.