华中区域年极端小时降水特征分析

Spatio-temporal distribution characteristics of annual extreme hourly rainfall over central China

利用1981—2017年近37 a华中区域241个气象观测站年最大小时降水资料,分析了该区域年极端小时降水的时空分布特征。结果表明:阈值分别为30~<40 mm·h^-1、40~<50 mm·h^-1和≥50 mm·h^-1的年极端小时降水频次,河南和湖北中东部均较高,湖南则随其阈值增大而降低;年极端小时降水频次日变化特征较为明显,午后至傍晚发生最多,前半夜至凌晨次之,后半夜至早晨、上午至午后明显减少;年极端小时降水平均强度大值区多集中在河南和湖北的中东部地区,湖北最强年极端小时降水大值区主要位于沿江汉平原边缘地带;年极端小时降水频次日峰值主要出现在午后至傍晚和后半夜至早晨,其区域性差异较为明显;不同阈值的年极端小时降水频次均表现出明显的年际和年代际变化特征,1980年代呈波动减小趋势,1990年代呈波动增加趋势,21世纪初期呈现低频波动变化,之后波动加大;不同阈值的极端小时降水频次日变化均表现为明显的单峰型特征,峰值出现在17时前后。

Based on the annual maximum hourly rainfall data at 241 national meteorological stations over central China during 1981-2017,we have conducted an analysis of the spatio-temporal distribution characteristics of annual extreme hourly rainfall in central China.The results indicate that the annual extreme hourly rainfall frequency that the thresholds are respectively equal to 30 mm·h^-1 and less than 40 mm·h^-1,equal to 40 mm·h^-1 and less than 50 mm·h^-1 and greater than or equal to 50 mm·h^-1 is higher in Henan and the central and eastern Hubei,while it decreases with the increase of the thresholds in Hunan.The diurnal variation of annual extreme hourly rainfall frequency is characterized by which is most occurred between afternoon and evening,the second between the first midnight and the morning,and is decreased significantly between midnight and the morning,morning and the afternoon.The high mean intensity of annual extreme hourly rainfall is mostly in the central and eastern parts of Henan and Hubei.The high value centers of annual extreme hourly rainfall in Hubei are mainly located in the edge of the Jianghan Plain.The daily peak of annual extreme hourly rainfall frequency mainly occurs from afternoon to evening and after midnight to morning,and it shows obvious regional difference.The annual extreme hourly rainfall frequency with different thresholds all show obvious interannual and interdecadal variation characteristics,which showed a fluctuating reduction trend in the 1980s,a fluctuating growth trend in the 1990s,and low-frequency fluctuation in the early 21st century and then increased in volatility.The diurnal variation of extreme hourly rainfall frequency with different thresholds all show obvious single-peak structure characteristics,and the peak appears around 17∶00 BT.