近45年长江中下游地区汛期极端强降水事件分析  

Analysis of Extreme Heavy Precipitation Event over the Mid-Lower Reaches of Yangtze River in Flood Season During Last 45 Years

作　　者：张天宇[1] 程炳岩[1] 刘晓冉[1] 

机构地区：[1]重庆市气候中心,401147

出　　处：《气象》2007年第10期80-87,共8页Meteorological Monthly

基　　金：中国气象局气候变化专项(CCSF2007-24)

摘　　要：利用长江中下游地区1960—2004年78个台站汛期(4—9月)逐日降水资料,首先定义了不同台站的极端强降水阈值,然后统计出了不同台站近45年逐年汛期极端强降水事件的发生频次,并进行了时空分布特征分析。结果表明:长江中下游汛期极端强降水事件发生频次的多寡很大程度上影响着汛期总降水量的多少。一致性异常分布特征是长江中下游地区汛期极端强降水事件发生频次的最主要空间模态;长江中下游地区汛期极端强降水事件发生频次的空间分布可分为5个主要区域。通过最大熵谱估计分析表明,Ⅰ区显著周期为2～4年;Ⅱ区和Ⅳ区的主要显著周期是基本一致的,显著周期为2～3年和6.3年;Ⅲ区显著周期为14.7年的年代际变化;Ⅴ区显著周期为22年的年代际变化和4～5年的年际变化。各分区代表站中岳阳(Ⅰ区)表现为很显著的增长趋势,10年增长率为1.0次;南岳(Ⅱ区)和南京(Ⅳ区)增长趋势相对较弱;衢州(Ⅴ区)增长趋势相对最弱;而洪家(Ⅲ区)近45年来汛期极端强降水事件发生频次则表现为很弱的减少趋势。Based on the daily precipitation data of flood season （from April to September） in 1960 - 2004 from 78 stations over the Midower Reaches of Yangtze River, the extreme heavy precipitation threshold values for every station was firstly determined, then the extreme heavy precipitation event frequency in flood season was counted and their temporal and spatial characteris tics are analyzed. The results show that the extreme heavy precipitation event frequency greatly affects the amount of total precipitation in flood season. The consistent anomaly distribution is the main spatial model of extreme heavy precipitation event frequency over the Mid-Lower Reaches of Yangtze River. The spatial distribution of extreme heavy precipitation event frequency can be divided into five main regions. The maximum entropy spectral estimation analysis shows that 2- 4 years period is significant in region Ⅰ; the major notable cycle is basically the same in regions Ⅱand Ⅳ, including significant periods of 2 - 3 years and 6.3 years; 14.7 years period of interdecadal variation is notable in region Ⅲ; 22 years period of inter-decadal variation and 4 - 5 years period of inter-annual variation are significant in region Ⅴ. In all of the representative stations, Yueyang （region Ⅰ） reveals a very significant growth trend, i.e. once per 10a; Nanyue （region Ⅱ） and Nanjing （region Ⅳ） have a rather weak growth trend; the growth trend of Quzhou （region Ⅴ） is weakest; and Hongjia （region Ⅲ） shows a weak decline trend in the last 45 years.

关 键 词：长江中下游 汛期 极端强降水事件 频次 

分 类 号：P457.6[天文地球—大气科学及气象学]