摘要
利用拉萨1952-2005年逐月降水量,≥0.1mm、1.0mm、5.0mm和10.0mm年降水日数,分析了近半个世纪拉萨年、季降水量及年降水日数的年际和年代际变化。结果发现:近半个世纪以来,拉萨年降水量表现为前30年呈不显著的减少趋势,减幅为17.8mm/10a;季降水量除夏季呈不显著的减少趋势外,其它各季均表现为增加趋势,以秋季增幅最大;≥0.1mm、≥1.0mm和≥5.0mm年降水日数表现为不同程度的增加趋势。近25年≥10.0mm的年降水日数呈极显著的增加趋势。20世纪50年代至80年代夏季降水量表现为逐年代减少趋势,秋季降水量则呈逐年代增加趋势,而冬季降水量为负距平。各等级年降水日数20世纪80年代偏少,90年代偏多。年降水量异常偏旱年主要出现在20世纪80年代,50年代和60年代的初期各出现一次异常偏涝年,70年代从未出现过异常年份。14年振荡周期可能是影响年降水量的主导周期。
Lhasa is positioned at the South of the Qinghai -Xizang Plateau with a temperate and climate, annual average rainfall of 426.5mm. Summer drought takes place frequently here with a semi-arid plateau distinct precipitation variation, which obviously influences the agricultural production. On the basis of climate diagnosis and analysis methods, this paper presents the detailed study on the characteristics of the interannual - interdecadal variation of precipitation and rainfall day in the recent 50 years. Using the data of monthly rainfall and annual rainy days from 1952 to 2005 in ere analyzed. The results show that the annual rainfall displayed insignific Lhasa of Tibet, the interannual and interdecadal variations of the annual and seasonal rainfall, annual rainy days want decreasing trend in Lhasa in former 30 years（ 1952 - 1980） with a decrease of 17.8mm/10 a, but the significant increase for annual rainfall indicated an increase of 90.6 mm/10 a in the last 25 years（ 1981 -2005 ）. In past 50 years, the trend of seasonal rainfall was increase in all season （except summer）, days of ≥0.1 mm≥1.0 mm and ≥5.0mm were increase in especially in autumn. In addition, the annual rainy past 50 years. The trend of increase for annual rainy days of ≥10.0mm was significant with an increase of 3.6d/10a in the last 25 years. However, from the 1950s to 1980s, the interdecadal variations of rainfall was decreased in summer, increased in autumn, whereas negative a- nomaly in winter. The annual rainy days were less in 1980s, more in the 1990s. The years with exiguous annual rainfall and anomalous drought appeared in 1980s, one anomalous moistness year in both early 1950s and early 1960s, and there were no anomalous years in the 1970s. The annual rainfall in Lhasa during recent 50 years had mainly the oscillation periods of quasi 14 years.
出处
《干旱区地理》
CSCD
北大核心
2008年第3期397-402,共6页
Arid Land Geography
基金
国家自然科学基金项目(40565002)
关键词
降水量
降水日数
年际和年代际变化
异常年份
小波分析
rainfall
rainy days
interannual and interdecadal variations
anomalous years
wavelet analysis
