基于标准化降水蒸散指数的宁夏中部干旱带干旱趋势分析

Analysis of Drought Trend in Arid Zone of Central Ningxia Based on Standardized Precipitation Evapotranspiration Index

基于标准化降水蒸散指数(SPEI),选取1960~2012年宁夏中部干旱带的海原、同心、麻黄山、兴仁、盐池五个气象站的降水和平均气温资料作为代表,计算各站SPEI序列,研究宁夏中部干旱带在不同时间尺度、不同季节尺度下的干湿演变趋势、干旱发生强度和频次变化以及干旱发生范围变化。结果表明:①SPEI中起决定性作用的因素是降水;②SPEI值的变化对不同时间尺度的敏感性不同,时间尺度越小,干湿变化趋势越明显,甚至是正负波动振荡;③宁夏中部干旱带干湿变化明显,不同季节均呈湿润化趋势,且以轻度干旱和中度干旱为主,干旱发生范围和干旱发生强度总体呈缩小趋势。

Based on the standardized precipitation evapotranspiration index( SPEI),the precipitation and average temperature data of Haiyuan,Tongxin,Mahuangshan,Xingren and Yanchi meteorological stations in the arid zone of central Ningxia from 1960 to 2012 were selected as representatives to calculate the SPEI value series of each station,and to analyzed the arid zone of central Ningxia at different time scales and different seasonal scales,the trend of dry and wet evolution,the intensity and frequency of drought occurrence and the change of drought occurrence range are also discussed. The results show as follows.①The precipitation is the decisive factor in the standardized precipitation evapotranspiration index( SPEI).②The change of SPEI value has different sensitivity to different time scales,the smaller the time scale,the more obvious the trend of dry-wet change,even the oscillation of positive and negative fluctuations.③Dry and wet changes are obvious in the arid zone of central Ningxia,with the trend of wetting in different seasons,and mild drought and moderate drought are dominant,and the occurrence range and intensity of drought are generally decreasing.