全球变暖给青藏高原三江源地区的降水时空演变带来极大不确定性,为积极应对气候变化,有必要对该地区降水时空演变特征进行分析。果洛州是三江源典型地区之一,依据果洛州境内玛多、达日和班玛3个代表站点1967—2019年的降水观测资料,利用Mann-Kendall趋势检验法、R/S分析法、滑动平均差检测法、Mann-Kendall突变检验法、Morlet小波分析和克里金插值等方法,从趋势性、突变性、周期性和空间分布上综合分析果洛州降水时空演变特征。结果表明,1967—2019年果洛州面平均降水M-K统计量Z值为4.96,线性倾向率为4.01 mm/a,呈显著递增趋势,R/S分析Hurst指数为0.90,表明趋势具有强持续性;1980—1981年存在跳跃突变,该突变使得果洛州年际面平均降水量增大55%;存在以28 a为第一主周期的周期变化特征;面平均降水空间等值线分布自西北293 mm向东南693 mm递增,4 200 m以上海拔地区平均降水量约370 mm,3 500 m及以下海拔、河谷地区平均降水量约560 mm,降水随高程变化差异明显。研究结果可为准确分析三江源地区气候变化原因、水文循环过程提供重要的科学依据。

Global warming has brought about great uncertainty to the temporal and spatial evolution of precipitation in the headwaters of the Three Rivers on Qinghai-Tibet Plateau. The temporal and spatial evolution of precipitation in the headwaters region need to be analyzed in response to climate change. According to observed precipitation data from 1967 to 2019 at three representative stations, namely, Maduo, Dari and Banma in Guoluo Prefecture, a typical region in the headwaters, we investigated comprehensively the temporal and spatial evolution of precipitation from perspective of trend, abrupt change, periodicity and spatial distribution by using Mann-Kendall trend test, R/S analysis, Mann-Kendall abrupt change test, moving average difference detection, wavelet analysis and Kriging interpolation. Results unveiled that the M-K statistic Z value of areal average precipitation from 1967 to 2019 in Guoluo reached 4.96, and the linear tendency rate 4.01 mm/a, showing a significant increasing trend; Hurst index amounted to 0.90, indicating that the trend was strong. Abrupt change occurred in 1980-1981, which raised the interannual areal average precipitation in Guoluo by 55%. A periodic variation of 28 a was detected as the first major period. The spatial contour of areal average precipitation saw a progressive increase from 293 mm in the northwest to 693 mm in the southeast. Moreover, precipitation varied remarkably with elevation. The average precipitation in areas above 4 200 m above sea level was about 370 mm, and areas above 3 500 m above sea level and valley regions around 560 mm. The research findings offer an important scientific basis for accurately analyzing the causes of climate change and the hydrological cycle in the headwaters of the Three Rivers.