Variation patterns of extreme precipitation and relation to ocean-atmospheric climate in Sichuan province China from 1961 to 2017

Based on daily precipitation records in the Sichuan province, spatiotemporal changes in extreme precipitation from 1961 to 2017 and the relation to ocean-atmospheric climate were investigated. The trends and their statistical significance were computed with the nonparametric Sen's and Mann-Kendall tests. The characteristics of mutation and period were investigated with heuristic segmentation and continuous wavelet transform. The relations between extreme precipitation and ocean-atmospheric climate were diagnosed by cross-wavelet analysis. The results comprised three aspects. (1) The intensity, frequency, and duration of extreme precipitation increased in the Sichuan plateau, while the intensity and frequency of extreme precipitation decreased, but the duration of extreme precipitation did not change in the Sichuan basin. The contrary trends of extreme precipitation indices may have been influenced by the complex local geography, dramatically increased human activity, and source transportation of water vapor. (2) Temporally, the trends in extreme precipitation indices constituted slight changes in the Sichuan province. The Sichuan province experienced notable climate change because abrupt change points were observed for most of the extreme precipitation indices. Extreme precipitation was a fluctuation process from 1961 to 2017. (3) Because there was a decrease in precipitation during the warm phase periods of El Nino events and an increase during the cool phase periods of La Nina events in the Sichuan province, we show that the El Nino-Southern Oscillation (ENSO) has longer and stronger relations with extreme precipitation than the South Asian Summer Monsoon (SASM) or East Asian Summer Monsoon (EASM). The results of the present study will facilitate better decisions concerning preparedness for extreme precipitation events and management of water hazards in the Sichuan province.