1961-2017年东帕米尔高原极端升温过程气候变化特征

利用塔什库尔干、吐尔尕特和乌恰3个气象站1961年1月1日至2017年12月31日的逐日最高气温,建立了中巴经济走廊北端东帕米尔高原单站升温过程数据库,用百分位法基于综合强度指标遴选出极端升温过程,对比分析了该区域塔什库尔干等3站的极端升温过程频数、强度气候变化特征。结果表明:(1)1961—2017年,东帕米尔高原塔什库尔干共出现489次极端升温过程,平均每年出现8.6次。塔什库尔干极端升温过程平均持续3.6 d,以持续3 d的最多,占24.7%,吐尔尕特和乌恰以持续2～3 d的极端升温过程为主。塔什库尔干的极端升温过程在7月出现最多,吐尔尕特在5月最多,乌恰在1月最多。(2)塔什库尔干综合强度最强的1次升温过程出现在2008年2月20—21日。东帕米尔高原3站的极端升温过程综合强度均在冬季最强。(3)57 a来,东帕米尔高原塔什库尔干年极端升温过程频数呈显著的线性增加趋势,增加率为0.57次·(10a)~(-1),进入21世纪以来,极端升温过程相对频发,年际间变率加剧。吐尔尕特与乌恰的线性变化趋势不显著。(4)57 a来,塔什库尔干的极端升温过程强度呈显著的线性增强趋势,且近年来年际间变化幅度加剧;乌恰的过程强度略呈下降趋势,近年来年际间变化幅度趋于平缓。总之,塔什库尔干7月的极端升温过程最多,57 a来年极端升温过程频数显著增多、强度显著增强,近年来极端升温过程频数及强度的年际间变化幅度均加剧,造成东帕米尔高原区域融冰(雪)洪水及其衍生地质灾害频发,风险加剧。

Change Characteristics of Extreme Temperature-rising Process in the East Pamirs during 1961—2017

The single-station databases of temperature-rising process at 3 meteorological stations including Tashkurgan, Turgart and Wuqia in the east Pamirs were established using the data of daily maximum temperature from January 1, 1961 to December 31, 2017. The three databases of extreme temperature-rising process were selected using the percentile method of comprehensive intensity. The change characteristics of frequency and intensity of extreme temperature-rising process at the three stations were compared and analyzed. The results showed that: ① There were totally 489 extreme temperature-rising processes, and the annual average was 8.6 times at Taxkorgan Meteorological Station in the east Pamirs from 1961 to 2017. At Taxkorgan, the average duration of extreme temperature-rising process was 3.6 days, the occurring frequency of 3-day duration was the highest and accounted for 24.7% of the total. The 2-3-day duration was dominant at Turgart and Wuqia. The extreme temperature-rising process occurred most frequently in July at Taxkorgan, in May at Turgart and in January at Wuqia; ②The extreme temperature-rising process with the strongest comprehensive intensity at Taxkorgan occurred during February 20-21, 2008. The comprehensive intensity of extreme temperature-rising processes was the strongest in winter at the 3 stations in the east Pamirs; ③ In recent 57 years, the annual frequency of extreme temperature-rising process was in a significant linear increasing trend, and the decadal increase rate was 0.57 times at Taxkorgan. The extreme temperature-rising process was relatively frequent from the beginning of the 21st century, and the interannual variability was intensified. The linear trend of the annual frequency of extreme temperature-rising processes was not significant at Turgart and Wuqia；④In recent 57 years, the intensity of the extreme temperature-rising process was in a significant linear increasing trend, and the interannual variation was intensified in recent years. The intensity of extreme temperature-rising process was slightly decreased, and the range of interannual change was decreased in recent years at Wuqia. In a word, at Taxkorgan, the extreme temperature-rising process occurred most frequently in July. The frequency and intensity of extreme temperature-rising process increased significantly at Taxkorgan in past 57 years, and the interannual variation intensified in recent years. Ice-snow melting floods and their derivative geological hazards occurred frequently along the northern section of the “China-Pakistan Economic Corridor” in the east Pamirs.