西双版纳勐仑地区降雨特征及变化趋势分析

AN ANALYSIS OF THE CHARACTERISTICS OF RAINFALL AND LINEAR TREND IN THE MENGLUN AREA OF XISHUANGBANNA,SW CHINA

关键词:  西双版纳  降雨量  降雨日数  变化趋势

Key words:  Xishuangbanna  rainfall  rainy days  linear trend

摘要:

为分析我国内陆热带地区的降雨特征及变化规律,利用中国科学院西双版纳热带森林生态系统定位研究站(西双版纳,勐仑)12年(1992~2003年)的雨量观测资料,对勐仑地区的降雨特征及趋势进行了分析。结果表明,勐仑地区1992~2003年间多年平均降雨量为1 555.1 mm,干、雨季分别占全年降雨量的15.8%和84.2%;降雨量在各月的分配为典型的单峰型曲线;昼、夜雨量相当,干季夜雨量略占优势,而降雨量较大的6、7月份则昼雨更占优势,6~8月的14~18时为全年降雨量的高值中心;年平均雨日为147 d,雷暴日为96 d;降雨强度分布的季节差异较大,干季以小强度降雨为主,而大雨基本集中在雨季,<25 mm/d的中小型降雨占了全年总雨日的91%。从12年的变化趋势来看,年、干季和雨季的降雨量、雨日及夜雨量都呈现不同程度的上升趋势,而昼雨量趋于平稳;除干季外,年、雨季的雷暴日都有所下降。可以认为,西双版纳地区降雨既有热带季风气候的特征,也有其自身的特点,由此带来的森林水文生态效应值得探讨。

Abstract:

In order to analyze the characteristics and development trend of rainfall of inland tropical area in China,rainfall in the Menglun area were studied based on the 12-year observations of Xishuangbanna tropical rainforest ecosystem research station of CERN.Data on rainfall was collected both automatically on an hourly basis and artificially on a daily basis from 1992 to 2003.During the research period,the annual gross rainfall was 1555.1mm with 15.8% in dry season and 84.2% in rainy season,and the monthly variation of rainfall during a year presented a single-peak pattern.There was no clear difference between annual night and daytime rainfall,and night rainfall was slightly more than daytime rainfall in dry seasons,but daytime rainfall was more dominant in June and July.There was a peak value of rainfall during the afternoon from June to August.The mean annual rain day was 147d and thunderstorm day was 96d.The distributions of rainfall intensity were greatly different between two seasons,and the light rain was dominant in dry seasons and heavy or torrential rain was dominant in rainy seasons.Light and moderate rain(<25mm) accounted for 91% of annual rain days.In terms of change of rainfall from 1992 to 2003,rainfall,rain day and night rainfall in both dry and rainy seasons ascended to various extents,but daytime rainfall presented no clear ascending or descending trend.The thunderstorm day in dry seasons kept ascending while that in rainy seasons was descending.As a result,the rainfall in Xishuangbanna have the not only characteristics of tropical monsoon climate,but also its own traits,so it is necessary to research on eco-hydrological effect in local forest ecosystem due to the input of rainfall.