双月刊

ISSN 1006-9895

CN 11-1768/O4

川渝地区夏季极端降水日变化特征分析
作者:
作者单位:

1.重庆市气候中心;2.南京大学大气科学学院

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基金项目:

中国气象局创新发展专项(CXFZ2021Z033、CXFZ2021J019、CXFZ2021Z011)、重庆市气象局开放式研究基金(KFJJ-201606)、重庆短期气候数值预测业务平台建设。


Analysis of diurnal variation characteristics of summer extreme precipitation in Sichuan and Chongqing
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Affiliation:

1.Chongqing Climate Center,Chongqing;2.School of Atmospheric Science,Nanjing University,Nanjing

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    摘要:

    利用川渝地区1991-2012年夏季逐小时降水资料,分析该地区总降水、极端降水时空分布特征,特别是极端降水的日变化特征。结果表明,川渝地区受西高东低的地形影响,总降水PA也呈西少东多分布,具体是川西北高原少川西南山地及东部盆地多,盆周山区多盆中丘陵区少;降水频率PF则呈西高东低的相反分布,高原地区PF较高;降水强度PI的分布与PA较为一致,自西向东逐渐增强。极端降水PA、PF、PI的空间分布特征与总降水的空间分布特征相似。东部的四川盆地乐山、雅安地区和达州、广元地区,以及西南山地区的西昌、攀枝花地区的降水量大主要是由于降水强度大。西昌地区北方小部分西南山地区的降水量大主要是由于降水频率大。川西高原区降水量小是因为降水强度小。PA日峰值自西向东递增,PF日峰值呈相反变化趋势,自西向东递减。两者几乎全部都出现在夜间,“夜雨”特征显著。海拔较高的地区日峰值大多出现在前半夜,而海拔较低的地区大多出现在后半夜,自西向东日峰值出现时间逐渐推迟,因此川渝地区的降水系统存在自西向东传播的特征。极端降水日峰值及其出现时间的分布特征都与总降水相似。川渝地区夏季小时极端降水的阈值西低东高,自西向东逐渐增大,极端降水频率占总降水频率的比重几乎都在40%左右,无明显差异。极端降水量占总降水量的比重自西向东呈增大趋势,极端降水量对川渝地区东部总降水量贡献大,对西部贡献较少。总降水时空分布特征和极端降水相似。四类站点的典型形态降水日变化曲线分析表明,川西大部分高原区和部分山地区为类型一,该地区降水量最少,但是降水频率最高;川西南部攀枝花市附近的小部分山地区以及四川盆地的成都、眉山、资阳、内江一带为类型三,该地区降水量较多;四川盆地中东部地区,以及重庆东部边缘地区为类型四,该地区降水量也较多,且具有明显的过渡特征,三个变量的相对大小表现的较为复杂;最后剩下的高原山地区和四川盆地西部为类型二,包括了降水量最大的乐山、雅安地区,该地区夏季降水充沛,且易发生暴雨;区域的海拔越高,夜间PF日峰值就越大;位于高海拔地区的类型一区PI明显偏弱;三个变量的分布都和其空间分布吻合度较高;三者日峰值的出现时间均自西向东从第一天晚上推迟到第二天清晨,极端降水PA、PF日变化均呈现凌晨单峰结构,“夜雨”特征明显,日峰值均出现在凌晨3:00左右,谷值均出现在午后13:00左右,PI则呈锯齿状波动结构,5:00-11:00时较低,其他时间较高。PA谷值主要受PF影响,而峰值则主要受PI和PF都较高的影响。

    Abstract:

    Hourly precipitation data in the summer of 1991-2012 in Sichuan and Chongqing were used to analyze the spatial and temporal distribution characteristics of total precipitation and extreme precipitation, especially the diurnal variation characteristics of extreme precipitation. The results show that the total precipitation PA in Sichuan and Chongqing is mostly distributed like less in the west and more in the east for the influence of the terrain with higher west and lower east. Specifically, there are more precipitation in the eastern Sichuan basin and mountains of southwest of Sichuan, less in plateau of the northwest while more in the mountains around the Sichuan basin and less in the Basin. The precipitation frequency PF was higher in the west and lower in the east inversely, the higher PF in the plateau. The distribution of precipitation intensity PI is likely with that of PA which increases gradually from west to east. The spatial distribution characteristics of PA, PF and PI of extreme precipitation are similar to those of total precipitation. The greater precipitation in the eastern Sichuan basin such as Leshan, Ya"an, Dazhou and Guangyuan and in the mountains of southwest of Sichuan such as Xichang and Panzhihua are mainly due to the greater precipitation intensity. The larger precipitation in a small part of the southwest mountain in the north of Xichang is mainly due to the higher precipitation frequency. The less precipitation in the western plateau of Sichuan is due to the lower precipitation intensity. The daily peak of PA increased from west to east, while the daily peak of PF showed an opposite trend, decreasing from west to east. Almost all of them occur at night, and the "night rain" feature is very prominent. Most of the daily peaks in the higher altitude areas occur in the before midnight while lower altitude areas in the after midnight. The time of the daily peaks in the areas from west to east delays gradually which indicated the precipitation system spreading from west to east in Sichuan and Chongqing. The distribution characteristics of daily peak of extreme precipitation and its occurrence time are similar to the total precipitation. The threshold of hourly extreme precipitation in summer in Sichuan and Chongqing is lower in the west and higher in the east, and gradually increasing from the west to the east. The extreme precipitation frequency accounts for almost 40% of the total precipitation frequency, with no significant difference. The proportion of extreme precipitation in the total precipitation increased from west to east, and extreme precipitation contributed more to the total precipitation in the eastern than western of Sichuan and Chongqing. The spatial and time distribution of total precipitation is similar to that of extreme precipitation. The analysis of the diurnal variation of typical precipitation at four types shows that most plateaus and mountains in the western of Sichuan are type 1, which have the least precipitation but the highest precipitation frequency. A small mountainous area near Panzhihua and Sichuan Basin including Chengdu, Meishan, Ziyang and Neijiang are type 3, which have more precipitation. The central and eastern parts of Sichuan Basin and the eastern edge of Chongqing are type 4, which also have more and obvious transitional characteristics, with complex characteristics of three precipitation variables. Finally, the rest region including plateaus, mountains and the western part of the Sichuan Basin are type 2, which including Leshan and Ya "an areas with the most precipitation and have abundant precipitation and rainstorms in summer. The higher the altitude of the region, the greater the daily peak of PF at night. The PI of the type 1 region with higher altitude is obviously weak. The distribution of the three precipitation variables is in good agreement with the spatial distribution. The occurrence time of the daily peaks of the three variables was postponed from west to east from the first night to the next morning, and the occurrence time of the lower value was postponed from west to east from noon to the evening. The daily changes of extreme precipitation PA and PF all show a single-peak structure in the early morning, and the "night rain" features obviously, the daily peak occurs around 3:00 in the morning, the lower value near 13:00 in the afternoon, the PI shows a jagged structure which is lower between 5:00 and 11:00 and higher at the rest times. The PA lower value is mainly affected by PF while the peak value is mainly affected by higher PI and PF.

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  • 收稿日期:2021-02-18
  • 最后修改日期:2021-08-29
  • 录用日期:2021-12-09
  • 在线发布日期: 2021-12-13
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