Abstract: To investigate the precipitation variation trends and differences between the new and old climate normals in Bengbu,this paper analyzes the differences and changes of precipitation at different time scales （annual,seasonal,monthly,and flood season） under the old and new climate normals based on the daily precipitation data from 4 national basic meteorological stations in Bengbu from 1981 to 2020. Findings reveal that under climate normal P2,the annual average precipitation in Bengbu increased,with the increase mainly concentrated in summer. The annual number of precipitation days remained nearly unchanged,characterized by a decrease in spring and summer and an increase in autumn and winter. Among them,both precipitation amount and precipitation days in Guzhen increased simultaneously. The precipitation changes in various regions were consistent in most months. For example,in June,precipitation increased significantly,while the number of precipitation days decreased,with a notable increase in precipitation intensity and extreme precipitation events. During the flood season,the precipitation amount and number of precipitation days of light rain,moderate rain,and heavy rain decreased,while those of rainstorms increased.

Key words: Bengbu City, new and old climate normals, precipitation regimes