Spatiotemporal variations of extreme precipitation events at multi-time scales in the Qinling-Daba mountains region, China

摘要

Global climate change has contributed to frequent occurrence of extreme precipitation events, resulting in more severe natural disasters and restricting regional development. The Qinling-Daba mountains region (Qinba) is a transitional zone in central China with high ecological vulnerability and sensitivity. It is therefore essential to investigate the dynamics of precipitation extremes in the region. In this study, spatiotemporal variations of extreme precipitation events were analyzed at the monthly, seasonal and annual timescales based on long-term daily precipitation dataset at 30 meteorological stations over the Qinba during 1961-2017. The results indicated all of the selected ten extreme precipitation indices exhibited non-significant trends at the annual scales. Seasonally, most of extreme precipitation indices decreased in spring, autumn and winter, and increased in summer, whereas consecutive dry days (CDD) increased in all seasons. At the monthly scales, wet precipitation extremes mostly occurred in July, and upward trends of extreme precipitation events dominated in February, June, July and August except for CDD. Spatially, regionwide increases in extreme precipitation events mainly distributed in the eastern and southern Qinba, whereas the north and west were dominated by decreasing trends. Most of atmospheric circulation indices, especially Arctic Oscillation (AO), Southern Oscillation Index (SOI) and Western Pacific Index (WP) were associated with extreme precipitation events at monthly and annual scales. East Asian Summer Monsoon Index (EASMI) and South China Sea Summer Monsoon Index (SCSSMI) strongly influenced extreme precipitation events in summer over the Qinba. Our results are conducive to understanding the variations of extreme precipitation events at the monthly, seasonal and annual scales, and these will be valuable for formulating the corresponding countermeasures at different timescales over the Qinba.