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

Yong Zhao,Anning Huang,Yang Wu,Xiaojing Yu,Xinning Dong,Shuxin Cai,Menyun Kan,Xindan Zhang

doi:10.1038/s41598-020-62535-5

Abstract

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.

Highlights

Weather and Joint Center for Atmospheric Radar Research of CMA/NJU, School of Atmospheric Sciences, Nanjing University, Nanjing, China, 210023. 3Glarun Technology Co., ltd, Nanjing, China, 211106. 4Chongqing Climate Center, Chongqing, China, 401147. 5Institute of Desert Meteorology, China Meteorological Administration, Urumqi, China, The extreme precipitation (EP) in China is common because of the East Asia monsoon systems and different climate zones due to the large variability of monsoonal climate and the unique distribution of topography with a vast land spanning many degrees of latitude and complex terrain, especially in the Yangtze River Basin (YRB)[9,19], where frequent floods caused by EP in summer inflict considerable loss of economy and human life[20]
We will focus on addressing such issues as follows: (1) How is the diurnal variation of EP with different duration along the YRB in warm season? (2) What is the feature of EP processes with different duration along the YRB during warm season in terms of their start, peak and end time? (3) How are the regional and sub-seasonal differences in the diurnal cycle of EP with different duration along the YRB during warm season? Findings of current study may provide the basic features of EP along the YRB in warm season at hourly time scale, which may be helpful to deepen our understanding of the EP processes and further improve the EP prediction
The diurnal percentage of the total precipitation amount (PA) shows a large center with the magnitude >40% located over the eastern Tibetan Plateau and the western Sichuan Basin, whereas the diurnal percentages in most parts of the middle and lower reaches of YRB are much smaller with the magnitude less than 25% (Fig. 3a)

Summary

Introduction

Weather and Joint Center for Atmospheric Radar Research of CMA/NJU, School of Atmospheric Sciences, Nanjing University, Nanjing, China, 210023. 3Glarun Technology Co., ltd, Nanjing, China, 211106. 4Chongqing Climate Center, Chongqing, China, 401147. 5Institute of Desert Meteorology, China Meteorological Administration, Urumqi, China, The EP in China is common because of the East Asia monsoon systems and different climate zones due to the large variability of monsoonal climate and the unique distribution of topography with a vast land spanning many degrees of latitude and complex terrain, especially in the Yangtze River Basin (YRB)[9,19], where frequent floods caused by EP in summer inflict considerable loss of economy and human life[20]. Recent studies based on the ground gauge observed data have indicated that the hourly EP frequently occurring along the YRB has shown an increasing trend[31,32,33].it is necessary to provide much more detailed information of EP at sub-daily time scales along the YRB. The hourly gauge-satellite merged precipitation product with the spatial resolution of 0.1° × 0.1° in latitude and longitude[35,36] during2008–2016 developed by National Meteorological Information Center of China(http://cdc.cma.gov.cn/home.do) is used in this study This dataset is generated from the gauge observed precipitation at more than 30,000 automatic weather stations in China combined with the CMORPH satellite precipitation product using the improved probability density function-optimal interpolation (PDF-OI) methods originally[37,38]. The cross-validation results suggest that this merged gauge-satellite precipitation product over China generated by the improved PDF-OI method shows much smaller bias, root mean square error and higher spatial correlation relative to the original PDF-OI derived precipitation product and good ability in capturing the varying features of hourly precipitation in heavy weather events[39]

Methods

Results

Conclusion