摘要
在新疆以往的降水不规则性的研究中常采用标准统计值,如距平值、标准离差和变差系数等来衡量降水对正常格局的偏离。然而,标准统计方法无法全面描述降水变化的不规则性。本文利用一种新的指标——偏差指数对新疆降水的时空不规则性进行分析,结果表明:南疆降水普通偏差指数要明显比其它两个区域高,而天山山区的指数值总体上最低。三个区域的特殊偏差指数存在一定的差异,这种差异性在20世纪90年代早期以前尤其明显,而90年代早期之后,三个区域降水的特殊偏差指数变化趋势大致呈现一致性,说明新疆降水时间变化上呈均匀化态势。天山山区的特殊偏差指数变化的幅度明显小于另外两个区域。北疆的特殊偏差指数在所分析的时段内存在微弱的线性降低趋势,而南疆,尤其是天山山区存在微小的线性增大趋势。降水不规则性指数可以较好地刻画新疆年降水的时空不规则性,该指标可以用于一般框架下的新疆未来降水变化监测。
Irregularity refers to significant changes in the stationary of rainfall phenomena （ e. g. , trend, variability or frequency distribution）. The area of Xinjiang with arid climate is characterized by rainfall irregularity. In the previous studies, standard statistics, such as standard deviation and variation coefficient were applied to describe the irregularity of precipitation in Xinjiang. However, common statistical methods could not give a fully graph of the irregularity and its evolution of the rainfall time series. This paper tries to describe the inter-irregularity of rainfall in Xinjiang based on different statistical techniques, especially the disparity indices. These indices are then applied to annual rainfall series of 51 observation stations over Xinjiang. The proposed indices are mutually complementary. The precipitation cumulative deviation graph is the first easy approach to the analysis of rainfall irregularity, though the main purpose of this method is to show the temporal distribution of dry and wet spells in the series. The cumula- tive deviations of annual precipitation series in three regions of Xinjiang, i. e. , the northern Xinjiang, southern Xinjiang and Tianshan Mountains, discriminate shifts from dry period during 1960s to mid-1980s to wet period thereafter. The evolution of irregularity was also studied by means of the running variation coefficient, calculated for a 5-year period. The results indicate a progressive decrease in variation coefficient of annual rainfall over the north- ern Xinjiang during the period of 1959 - 2008, and obvious increases in variation coefficients of annual rainfall over the northern Xinjiang and Tianshan Mountains in recent years. The general disparity index of annual preeipitation in the southern Xinjiang is obviously larger than that in the northern Xinjiang and dex of the Tianshan Mountains is the lowest. There were different precipitation the Tianshan Mountains, and the in- irregularity patterns among three re- gions before 1990s, thereafter a similar variation trend of rainfall irregularity was observed, demonstrating an evenly temporal evolution of annual precipitation in Xinjiang. The special rainfall disparity index of the Tianshan Mountains was marked smaller in variation scope than other two regions. A tiny linear decreasing trend in the spe- ces of precipitation can better describe the temporal and spatial irregularity of rainfall in Xinjiang. These indices could be employed to monitor future precipitation change in the general framework of climate change research in Xinjiang.
出处
《干旱区地理》
CSCD
北大核心
2010年第6期853-860,共8页
Arid Land Geography
基金
全球变化研究国家重大科学研究计划项目(973)(2010CB95001)
国家科技支撑计划(2007BAC03A0604)资助
关键词
年降水
不规则性
长期演变
新疆
annual precipitation
irregularity
long-term evolution
Xinjiang
