Response of Meiyu process considering the temporal and spatial characteristics of GNSS PWV

This study explores the spatiotemporal characteristics of Global Navigation Satellite System (GNSS) Precipitable Water Vapor (PWV) and its relationship with the Meiyu process. Using multiple sources of atmospheric PWV data and meteorological information, the study quantitatively analyzes PWV's spatiotemporal characteristics and its association with the onset and withdrawal of the Meiyu season. The research findings are as follows: (1)PWV's spatiotemporal evolution provides indications for the Meiyu season. The daily variation of water vapor content generally follows a camelback shape. Before the Meiyu season begins, PWV exhibits an upward trend with content below 40mm. After the onset of the Meiyu season, PWV gradually accumulates during the early Meiyu season with content exceeding 50mm, accompanied by rainfall. In the late Meiyu season, water vapor releases, leading to a decrease in PWV content. After the Meiyu season ends, PWV gradually declines but remains relatively high, linked to moisture transport during the Jianghuai flood season. (2)Anomaly analysis reveals that water vapor activity is highest during the Meiyu season, showing good correspondence with special Meiyu years. This provides new insights for monitoring and forecasting abnormal Meiyu events. (3)Spatially, PWV distribution during the Meiyu season exhibits a pattern of more water vapor in southern regions and less in northern areas. This pattern is influenced by the stronger atmospheric water storage capacity in low-latitude areas and the gradual weakening of monsoon water vapor during northward and westward transport.