1960~2023年新疆塔城地区汛期极端降水指数年变化特征分析

Analysis of the Annual Variation Characteristics of Extreme Precipitation Indexes during the Flood Season in Tacheng Prefecture, Xinjiang from 1960 to 2023

摘要: 利用近64年(1960~2023年)新疆塔城地区7个气象观测站汛期(5~9月)降水量资料，采用世界气象组织推荐的11个极端降水指数，分别讨论了其气候统计特征、时空变化特征、年变化特征，结果表明：① 近64a塔城地区汛期各极端降水指数空间分布总体呈自北向南逐渐减少的趋势，极值指数中RX1day最大值出现在塔城，RX5day最大值出现在和丰，最小值均出现在裕民；绝对指数中SDII最大值出现在裕民，R10、CDD、CWD最多均出现在托里，R20、R50最多均出现在塔城；相对指数极大值均出现在托里，极小值均出现在沙湾。② 塔城地区汛期各极端降水指数均以负距平为主，年际波动明显，且各站间差异较大，其中极值指数年际变化分为两个阶段，1960~2000年以负距平为主，期间有短暂的正距平，变化较为平稳，2001~2019年以正距平为主，波动起伏较大；绝对指数除CWD正负距平各出现32年外，其它均以负距平为主，且存在明显的年际波动，1960~1991年正负距平最长连续5年，但变化较为平稳，波动较小，1992~2014年变化加剧，2015~2023年变化剧烈，波动较大；相对指数1960~1974年以正距平为主，变化较为平稳，1974~2000年以负距平为主，2001~2019年以正距平为主，波动起伏均较大，2020~2023年以负距平为主，变化趋于平稳。③ 塔城地区汛期各极端降水指数年代际振荡明显，其中极值指数中RX1day最大值出现于21世纪初年，RX5day最大值出现于2000年代，且均在20世纪1990~2000年代经历了“多–多”的变化；绝对指数中R10和R20在20世纪1980~1990年代经历了“多–多”的变化，SDII和CWD在20世纪1980~1990年代经历了“少–多”的变化，R50和CDD在20世纪1990~2000年代~21世纪初年经历了“少–多–多”的变化；相对指数均以21世纪初年最多，1970年代最少，且均经历了“多–少–多–多–少–多”的交替演变。

Abstract: Utilizing precipitation data from the flood season (May to September) over the past 64 years (1960~2023) from seven meteorological observation stations in the Tacheng region of Xinjiang and employing eleven extreme precipitation indices recommended by the World Meteorological Organization (WMO), this study discusses their climatic statistical characteristics as well as temporal and spatial variation features. The results indicate that: ① from May to September in the Tacheng area over the past 64 years, the spatial distribution of extreme precipitation indices generally showed a decreasing trend from north to south. Among the extreme value indices, the maximum RX1day occurred in Tacheng, while the maximum RX5day occurred in Hefeng; the minimum values for both were observed in Yumin. For the absolute indices, the maximum SDII was recorded in Yumin, while the highest values of R10, CDD, and CWD were all found in Tuoli, and the highest R20 and R50 were both in Tacheng. The relative indices reached their maximum values in Tuoli and their minimum values in Shawan. ② The most extreme precipitation indices were dominated by negative anomalies, with significant interannual fluctuations and considerable variation among stations. The interannual variation of extreme value indices can be divided into two phases: there are negative anomalies prevailed from 1960 to 2000, with brief positive anomalies and relatively stable changes from 2001 to 2019, positive anomalies dominated, with larger fluctuations. Among the absolute indices, except for CWD, which had 32 years each of positive and negative anomalies, the others were predominantly negative, with notable interannual variability. From 1960 to 1991, the longest consecutive period of positive or negative anomalies was five years, with relatively stable and minor fluctuations. From 1992 to 2014, changes intensified, and from 2015 to 2023, variations became more drastic with significant fluctuations. For the relative indices, positive anomalies dominated from 1960 to 1974, with relatively stable changes; negative anomalies prevailed from 1974 to 2000, followed by positive anomalies from 2001 to 2019, with substantial fluctuations. From 2020 to 2023, negative anomalies dominated again, and changes tended to stabilize. ③ The extreme precipitation indices in the Tacheng area exhibited clear decadal oscillations. Among the extreme value indices, the maximum RX1day occurred in the early 21st century, while the maximum RX5day appeared in the 2000s, with both experiencing a “high-high” variation during the 1990s~2000s. For the absolute indices, R10 and R20 underwent a “high-high” variation during the 1980s~1990s, while SDII and CWD experienced a “low-high” variation during the same period. R50 and CDD showed a “low-high-high” variation from the 1990s~2000s to the early 21st century. The relative indices all peaked in the early 21st century and were lowest in the 1970s, following an alternating evolution of “high-low-high-high-low-high”.