1960~2021年塔城地区汛期降水集中度和集中期变化特征

Variation Characteristics of Precipitation Concentration and Concentration Period in Flood Season in Tacheng Area from 1960 to 2021

利用近62年(1960~2021年)塔城地区7个气象观测站汛期(5~9月)逐日、逐候降水量资料,分别讨论了集中度(PCD)和集中期(PCP)的时空分布特征、变化规律及其影响因子,结果表明:1) 塔城地区汛期PCD波动幅度介于0.26~0.41,平均为0.21;汛期PCP波动幅度介于39~41候,平均为36候。2) 塔城地区汛期PCD年际变化较平缓,呈逐年微弱的增加趋势,线性拟合递增率为0.01/10a,表明年内降水分配趋于均匀化;汛期PCP年际变化大,线性倾向率为−1.05候/10a,呈逐年显著推迟趋势(通过了0.05的显著性水平检验),表明候最大降水量出现时间逐年推迟。3) 塔城地区汛期PCD年代际变化经历了“降低–升高–降低–降低–升高–降低”的交替演变,其中1970年代为最高值,1990年代为最低值;PCP经历了“升高–降低–升高–升高–降低–升高”的交替演变,其中1990年代为最高值,1970年代为最低值。4) 塔城地区汛期PCD序列在1970年代初期、1990年代中期、21世纪中期发生过明显的由多到少和由少到多的突变,2019年为突变点;汛期PCP序列在1970年代初期、1980年代中期、2000年代中期发生过明显的由多到少和由少到多的突变,1990年为突变点。5) 塔城地区多雨年的PCD比少雨年大(或少雨年的PCD较多雨年偏小),多雨年的集中期比少雨年晚(或少雨年的PCP比多雨年早),各站空间分布差异较大。6) 塔城地区PCD和PCP与汛期降水、降水距平、距平百分率均呈正相关,但相关系数较小;比较而言,PCP与汛期降水、降水距平、距平百分率降水量的正相关程度更高,表明当塔城地区汛期降水偏多时,最大候降水出现日期越晚(推迟)。

Based on the daily and hourly precipitation data of 7 meteorological observation stations in Tacheng area during flood season (May to September) in recent 62 years (1960 to 2021), the spatial and temporal distribution characteristics, variation rules and influencing factors of PCD and PCP were discussed respectively. The results show that: 1) The fluctuation range of PCD in flood season in Tacheng area is 0.26~0.41, with an average of 0.21;The fluctuation range of PCP in flood season is 39~41 pentad, with an average of 36 pentad. 2) The interannual variation of PCD in flood season in Tacheng area is relatively gentle, showing a weak increasing trend year by year, and the linear fit-ting increasing rate is 0.01/10a, indicating that the annual precipitation distribution tends to be uniform;The linear tendency rate of PCP in flood season was −1.05 pentad/10a, which showed a significantly delayed trend year by year (passing the significance level test of 0.05), indicating that the occurrence time of the maximum precipitation in monsoon was delayed year by year. 3) The decadal variation of PCD in flood season in Tacheng area experienced the alternating evolution of “down-rise-down-rise-down-decrease”, with the highest value in 1970s and the lowest value in 1990s. PCP experienced the alternating evolution of “up-down-up-up-up-down-down-up-up”, with the highest value in the 1990s and the lowest value in the 1970s. 4) The flood season PCD sequence in Tacheng area had obvious mutations from more to less and from less to more in the early 1970s, the middle of 1990s and the middle of 21st century, and 2019 was the mutation point;The PCP sequence in flood season had obvious changes from more to less and from less to more in the early 1970s, mid-1980s and mid-2000s, and was the mutation point in 1990. 5) PCD in rainy years is larger than that in rain-less years (or PCD in rain-less years is smaller than that in rain-less years), and the concentration period in rainy years is later than that in rain-less years (or PCP in rain-less years is earlier than that in rain-less years). 6) PCD and PCP were positively correlated with precipitation, precipitation anomaly and anomaly percentage in flood season, but the correlation coefficient was small;In comparison, the positive correlation degree of PCP with precipitation, precipitation anomaly and precipitation percentage anomaly is higher, indicating that when there is more precipitation in flood season, the date of the maximum monsoon precipitation appears later (delayed).