石河子地区极端干湿事件变化特征

为探究气候变化下石河子地区极端干湿事件的演变特征，基于石河子地区1961—2012 年逐日气象资料，计算各气象站年和月的地表湿润指数，进行标准化后统计极端干湿事件频次，并进一步分析极端干湿事件的变化特征。结果表明，近52 年来，石河子地区极端干旱事件频次呈减少趋势，速率为-0.45 次/10 a；而极端湿润事件频次呈增加趋势，速率为0.39 次/10 a；夏半年和冬半年极端干旱事件频次均呈减少的趋势，变化速率分别为-0.20 次/10 a、-0.25 次/10 a；而夏半年和冬半年极端湿润事件频次呈增加趋势，速率分别为0.11 次/10 a 和0.12 次/10 a；突变分析表明，石河子地区年极端干旱和极端湿润事件频次分别在1986 年和1967 年发生突变；近52 年来石河子地区年极端干旱事件频次存在12~13 年左右的主周期和2~3 年的次周期，而极端湿润事件频次仅存在6~8 年的小周期。极端干旱事件的减少和极端湿润事件的增加表明气候变化下石河子地区的湿润化趋势。

Variation Characteristics of Extreme Drought and Wet Events in Shihezi Region

In order to investigate variation characteristics of extreme drought and wet events in Shihezi Region,annual and monthly surface humid indexes and the frequency of extreme drought and wet events were analyzed based on the daily data of the 4 meteorological stations in Shihezi Region from 1961 to 2012. The results showed that frequency of the overall trend of extreme drought events was decreasing from 1961 to 2012 with the rate of -0.45 times/10 a, while the frequency of the overall trend of extreme wet events was increasing in the same time range with the rate of 0.39 times/10 a. The frequency of extreme drought events in summer half year and winter half year presented a downward trend with the rate of -0.20 times/10 a, -0.25 times/10 a, respectively. Whereas, an increasing trend was obvious for the variation of the frequency of extreme wet events in summer half year and winter half year (0.11 times/10 a, 0.12 times/10 a). The abrupt change of the frequency of annual extreme drought and wet events happened in 1986 and 1967, respectively. The frequency of extreme drought events had a main cycle of 12-13 years and a second cycle of 2-3 years. However, the frequency of extreme wet events showed no obvious large scale time periods, but presented a small cycle of 6-8 years. The decreasing trend of extreme drought events and the increasing trend of extreme wet events indicated a significant humidification trend in Shihezi Region.