1951-2015年乌鲁木齐市极端升温过程气候变化特征

The Change Characteristics of Extreme Temperature-Rising Process in Urumqi City During 1951-2015

利用乌鲁木齐市气象站1951年1月1日至2015年12月31日逐日最高气温,建立了乌鲁木齐市升温过程数据库。在分析单要素强度指标及升温过程强度排序特征基础上,定义了一个升温过程综合强度指数(IZ),根据百分位排序法,整理出了乌鲁木齐市的极端升温过程,分析了过程的持续日数、发生频数以及强度的气候变化特征。分析结果表明:基于6项单要素强度指标,乌鲁木齐市最强升温过程有6种不同结果。基于IZ,1951—2015年乌鲁木齐市共出现567次极端升温过程,平均每年8.7次,强度最大的一次升温过程出现在2009年3月14—16日。乌鲁木齐市567次极端升温过程持续日数平均3.25 d,持续2 d的最多,占23.1%。1951—2015年,乌鲁木齐市极端升温过程持续日数在春季4月(5.37 d)最长,冬季1月(2.29 d)与12月(2.37 d)最短。65年来持续日数略减少,线性变化趋势不显著。1951—2015年乌鲁木齐市极端升温过程主要集中在冬半年的12—4月,占64.3%,1月最多;7月最少,仅占1.9%。65年来年极端升温过程发生频数呈不显著的线性增加趋势,从20世纪80年代以来基本上处于偏多时期,进入21世纪以来年际间变化幅度加剧。1951—2015年,乌鲁木齐市极端升温过程的综合强度指数无显著线性变化趋势,在20世纪50、60年代强度较强、年际间变率相对较大,之后强度逐渐减弱、年际间变率减小,进入21世纪以来强度增强、年际间变率加剧。

Based on the daily maximum temperature data at Urumqi meteorological station, we established the database of temperature-rising process of Urumqi city during the period of January 1 1951 to December 31 2015. A comprehensive strength index IZ was defned in terms of the intensity values and ranks of the temperature-rising process, and sorted the extreme temperature-rising processes in Urumqi according to IZ index percentile ranking. Thus, the change characteristics of the process sustained days, frequency and intensity were analyzed. The results showed that there were a total of 567 extreme temperature-rising processes in Urumqi during 1951-2015, and the average was 8.7 times per year. The maximum strength of the extreme temperature-rising process occurred in March 14-16, 2009. The average of sustained days was 3.25 d, and the number of sustained 2 d process was the most, accounting for 23.1% of the 567 extreme temperature-rising processes in Urumqi. The longest sustained days of extreme temperature-rising process was in April （5.37 d）, and the shortest was in January （2.29 d） and December （2.37 d） during 1951-2015. The annual sustained days of extreme temperature-rising processes decreased slightly, and the linear trend was not signifcant in the past 65 years. The extreme temperature-rising process was mainly concentrated in the period of December？April, accounting for 64.3%, and the least was only 1.9% in July of Urumqi. In the past 65 years, the frequency of extreme temperature-rising process was not signifcantly increased linearly, more than mean frequency after 1980s and increased in the beginning of 2010s of the inter-annual variability of frequency. Both the intensity and its inter-annual variability of extreme temperature-rising process were more than the average in 1950s and 1960s in Urumqi. The intensity gradually was weakened, and the inter-annual variability was decreased from 1970s to 2010s. Both the intensity and its inter-annualvariability were increased by the beginning of 21 century.