2005—2017年拉萨小时降水变化特征  

Characteristics of hourly precipitation in Lhasa during 2005—2017

作　　者：多典洛珠 周顺武[1] 郑丹 王传辉[3] 赤曲 Duodianluozhu;ZHOU Shun-wu;ZHENG Dan;WANG Chuan-hui;CHI Qu(Nanjing University of Information Science&Technology,Nanjing 210044,Jiangsu,China;Meteorological Observatory of Tibet Autonomous Region,Lhasa 850000,Tibet,China;Anhui Provincial Meteorological Bureau,Hefei 230061,Anhui,China)

机构地区：[1]南京信息工程大学,江苏南京210044 [2]西藏自治区气象台,西藏拉萨850000 [3]安徽省气象局,安徽合肥230061

出　　处：《干旱区地理》2020年第6期1467-1476,共10页Arid Land Geography

基　　金：国家自然科学基金项目(41175081,91337218,41605039)联合资助。

摘　　要：利用拉萨站2005—2017年汛期(5~9月)逐时地面观测资料,分析了拉萨逐年小时降水(降水量、降水频次和降水强度)的变化特征,结合谐波分析方法讨论了小时降水的日循环信号,最后对比了不同时长和等级的小时降水出现频次及其对总降水的贡献。结果表明:(1)拉萨逐年汛期小时降水以“单峰型”结构为主,峰值出现在夜间。(2)拉萨汛期小时降水变化为全日周期,其中盛夏(7~8月)期间的日循环信号最强。(3)拉萨汛期降水按持续时间可分为:短历时(1~3 h)、中历时(4~6 h)和长历时(>6 h)3种类型,其中短(长)历时降水出现频次最多(少),但其贡献率最小(大),短历时降水的日峰值出现在下午到前半夜,而中历时和长历时降水的日峰值出现在后半夜。(4)各等级小时降水中小雨(3>r≥1)和中雨(r≥3)对降水总量的贡献率明显大于微雨(1>r≥0.1),随着降水等级的上升,夜雨概率增大。Based on the hourly ground observation data of Lhasa station,Tibet,China during flood season(May to September)from 2005 to 2017,the variation characteristics of annual hourly precipitation(total,frequency,and intensity of precipitation)at the station are analyzed,discussing the daily cycle signal of hourly precipitation with harmonic analysis method.The frequency of hourly precipitation and its contribution to total precipitation are compared finally for different durations and grades.Results show that:(1)The diurnal variations of annual hourly precipitation in Lhasa are characterized by a“single peak”distribution,which appears at night.(2)The changes of hourly precipitation in Lhasa during the flood season is a full-day cycle,and the daily cycle signal is the strongest during midsummer(July to August).(3)According to the duration,the flood season in Lhasa can be divided into three types:short duration(1-3 h),medium duration(4-6 h),and long duration(>6 h),in which the short(long)duration of precipitation occurs most frequently(less),but its contribution rate is the smallest(large).Moreover,the daily peak value of short-term precipitation occurs in the afternoon to the middle of the night,while the daily peak value of mid-and long-term precipitation occurs in the second half of the night.(4)The contribution rate of light rain(1≤r<3)and moderate rain(r≥3)to the total precipitation is significantly greater than that of the light rain(0.1≤r<1).As precipitation levels rise,the probability of night rain increases.

关 键 词：小时降水 日变化 谐波分析 降水持续时间 降水等级 

分 类 号：P426.614[天文地球—大气科学及气象学]