Characteristics of Hourly Extreme Precipitation along the Yangtze River Basin, China during Warm Season

Based on the hourly gauge-satellite merged precipitation data with the spatial resolution of 0.1° × 0.1° during 2008–2016, the characteristics of extreme precipitation (EP) diurnal cycle along the Yangtze River Basin (YRB) and their regional and sub-seasonal differences during warm season have been indicated and revealed in this study. Results show that the EP amount (EPA) over most lower reaches of YRB exhibits two diurnal peaks with one in late afternoon and the other in morning, while the EPA over most eastern Tibetan Plateau (the Sichuan Basin and the northern Yunnan-Guizhou Plateau) generally peaks during late afternoon to midnight (midnight to early morning). The afternoon (morning) EPA diurnal peaks over the areas east to 110°E is mainly resulted from the short (long) duration EP events. However, both the short and long duration EP events lead to the nocturnal diurnal peaks and eastward propagating features of EPA over the regions west to110°E. The EP events over the Sichuan Basin generally begin at midnight and mostly peak around 03:00-04:00 Beijing time, and they start earlier and end later with the duration time increased. However, the EP events with short (long) duration over the lower reaches of YRB frequently start and peak in afternoon (early morning) and typically end at around 18:00 (07:00-08:00) Beijing time, and they start later (earlier) and end later with the duration time increased. Meanwhile, the EP frequency (EPF) diurnal cycles over the lower reaches of YRB exhibit obvious sub-seasonal differences in warm season, which show only a morning peak in the pre-Meiyu period, two comparable peaks with one in afternoon and the other in morning during the Meiyu period, and a predominant afternoon peak and a secondary morning peak in the post-Meiyu period, respectively. While the EPF over Sichuan Basin characterized by only one dominant early morning peak during all periods of the warm season exhibits much smaller sub-seasonal differences in the diurnal phase relative to that over the lower reaches of YRB.