海南岛夏季不同类型降水特征及其对旱涝的影响

Characteristics of different types of precipitation and their influences on drought and flood over Hainan Island in summer

基于海南岛18个国家地面气象观测站1966—2018年的逐日降水量资料和海南省逐日天气系统日历表,分析了海南岛夏季不同类型降水的特征,以及不同类型降水对夏季旱涝的影响。结果表明:(1)热带气旋降水(TCR)是夏季海南岛最重要的降水类型,占夏季降水(SUMR)的35.6%,其次是热带辐合带降水(ITCZR),占29.4%,西南季风槽降水(SWTR)和副高边缘降水(STHR)分别占15.3%和14.7%。(2)夏季不同类型降水及其对SUMR贡献率的空间分布具有不同的特征。(3)海南岛夏季TCR发生频次最少,但降水强度最大;ITCZR发生频次最多,降水强度为次大。大雨以上的强降水主要由TCR和ITCZR造成。(4)最近53 a,海南岛SUMR呈弱的增加趋势,这主要归功于ITCZR的显著增加,SWTR和STHR对其增加趋势为负贡献。SUMR的发生频次有微弱增加趋势,其中ITCZR的发生频次显著增加,SWTR和STHR的发生频次显著减少,TCR的发生频次微弱减少。SUMR的大雨和暴雨以上频次均为弱的增加趋势,其中ITCZR的相应频次均为显著增加趋势,其余三种类型的相应频次均为弱的减少趋势。(5)TCR和ITCZR对海南岛夏季旱涝有重要影响,它们的降水偏少年份往往出现夏旱,但对涝年的影响存在年代际变化。1990年代以前主要是TCR的显著偏多导致海南岛出现夏涝,1990年代开始TCR和ITCZR共同偏多导致海南岛的夏涝,并使得这一时期SUMR偏多的幅度增大。

Base on daily observational precipitation at 18 stations in Hainan province and the daily weather system in Hainan province during 1966—2018,the characteristics of different types of summer precipitation and its influence on summer drought and flood are analyzed.The result shows:(1)Tropical cyclone precipitation(TCR)is the most important precipitation type in summer over Hainan Island,accounting for 35.6%of summer precipitation(SUMR),followed by tropical convergence zone precipitation(ITCZR)accounting for 29.4%,and southwest monsoon trough precipitation(SWTR)and subtropical high edge precipitation(STHR)account for 15.3%and 14.7%,respectively.(2)The spatial distribution of different types of SUMR and their contribution rate to SUMR have different characteristics.(3)In summer,the frequency of TCR is the smallest,but its intensity is the largest over Hainan Island.The frequency of ITCZR is the largest,but its intensity is the second largest.Heavy rain and above are mainly caused by TCR and ITCZR.(4)In recent 53 years,SUMR in Hainan Island showed a weak increasing trend,which was mainly due to the significant increase of ITCZR.Conversely,SWTR and STHR contributed negatively to its increasing trend.The frequency of SUMR has a weak increasing trend,in which the frequency of ITCZR is significantly increased,the frequency of SWTR and STHR is significantly reduced,and the frequency of TCR is slightly reduced.The frequency of torrential rain and above has a weak increasing trend,the corresponding frequency of ITCZR has a significant increasing trend,and the corresponding frequency of the other three types have weak decreasing trends.(5)TCR and ITCZR have an important influence on the summer drought and flood over Hainan Island.Summer drought often occurs in the years with less TCR and ITCZR,but their influence on the summer flood has inter-decadal change,which results in the occurrence of summer flooding.It also leads to more precipitation in summer flooding years in this period.