Spatial-temporal variations of extreme precipitation indices and their linkage with atmospheric circulation in the middle and lower reaches of the Yangtze River

Abstract

Abstract Under the background of climate change, increasing frequency and intensity of extreme precipitation causes serious impacts and huge losses to society and economy. It is significant to analyze the spatial and temporal variation of extreme precipitation for regional risk assessment. Nine extreme precipitation indices were calculated using the daily precipitation data of the middle and lower reaches of the Yangtze River (MLYR) from 1979 to 2015. Linear trend analysis and the Mann-Kendall trend test were carried out to determine the variation trend of the nine extreme precipitation indices. In addition, the potential influences of anomalous atmospheric circulation factors on extreme precipitation were explored using the wavelet coherence analysis technique. The results show that: (1) the overall wetting trend is detected in the MLYR, and the PRCPTOT and RX1day increased significantly; (2) Extreme precipitation decreased from southeast to northwest in the MLYR, indicating that extreme precipitation events are more prone to occur in the southeast of the MLYR; (3) the Western Pacific Subtropical High (WPSH), the South China Sea high (SCSH) and the East Asian westerly jet (EAJ) all strongly impact on the changes of precipitation in the MLYR, among which the WPSH has the most significant impact, followed by the SCSH, and the EAJ is weaker.