基于CI指数的河南省近40a干旱特征分析

Analysis on Drought Characteristic of He'nan in Resent 40 Years Based on Meteorological Drought Composite Index

基于河南省113个气象站1970-2007实测气象资料,利用气象干旱综合指数对河南省近40a的干旱特征进行了统计分析。首先计算了历史逐日的C I指数,统计近40 a各站点出现的干旱过程、各时段的干旱事件,在此基础上统计了河南省历年各地区干旱发生的频率、覆盖范围,分析了干旱发生范围的年际变化和不同强度干旱的空间分布特征。分析结果表明：河南省伏旱发生频率最高为63.6%,冬季干旱发生频率最低为48.8%,春旱和秋旱发生频率相近,分别为55.4%和56.9%;全省大范围干旱发生的年份春季和秋季较多分别有9 a,冬季最少只有5 a;春季豫北各等级干旱发生天数均较高,夏季和秋季全省易发生大范围轻旱,重旱发生较少,冬季轻旱和中旱呈显著的纬向分布,南少北多,和降水的分布有较好的负相关性。

In this paper, the characteristics of the spatial and temporal variations of drought in He＇ nan province were statistically analyzed based on observed data from 1970 to 2007 of 113 stations by using the meteorological drought composite index. Firstly, the histor- ical day - to - day CI was calculated, and on the basis of the statistics on drought events in each station and each stage in resent 40 years in He＇ nan, the occurrence frequency and coverage area of drought in each station were calculated, then the annual variation of coverage area and spatial distribution of different classification of drought were analyzed. The results show that drought occurred in the highest frequency （63.6%） in summer and the lowest （48.8%） in winner, and in spring and autumn the frequency were 55.4% and 56.9% , respectively ; The large area drought in whole province occurred mostly in spring and autumn hut least in winter during the period of 1970 to 2007 ; In summer and autumn the large area light drought occurred easily in the whole province but the heavy drought occourred little; In winner the light and middle drought occurrence presented obvious latitude distribution with little in south and more in north, which had negative correlation with precipitation distribution.