青藏高原强降水量变化特征分析

Analysis of the Characteristics of Heavy Precipitation Changes in the Qinghai-Tibet Plateau

摘要: 青藏高原具有独特的地形地貌和地表特征，研究该地区极端降水变化特征对指导当地防灾减灾具有重大意义。本文利用CHM_PRE数据集，通过百分位阈值法计算极端降水阈值，并将阈值与极端降水指数强降水量(R95P)定义结合，计算出强降水量，运用线性倾向估计法、滑动t检验、M_K突变检验以及小波分析，对青藏高原区域的极端降水变化特征进行分析。主要结论如下：1) 青藏高原的极端降水平均阈值为12.43 mm，其空间分布呈现出自东南向西北递减的趋势。阈值最大的区域位于林芝市察隅县，阈值最低的区域主要分布在柴达木盆地和昆仑山地区。2) 青藏高原地区年和春夏秋季的强降水量空间分布与极端降水阈值的空间分布相近，都是由东南向西北递减。3) 近51年青藏高原年和夏季强降水量表现明显的年际变化，整体呈上升趋势，其他季节的变化趋势较小。4) 近51年青藏高原年、春、夏和秋季的强降水量变化趋势空间分布基本一致，呈增加趋势的区域大于呈减少趋势的区域。青藏高原东部、中部偏南的小部分区域基本呈减少趋势，其余区域则为增加趋势。5) 近51年青藏高原年和春季的强降水量变化周期以17年左右为主。夏季强降水量主要的变化周期是17年左右，此外，还存在26年左右的周期变化。秋季强降水量则存在25年、12年和3年三种周期，其中25年左右的周期最显著。6) 通过进行M_K突变检验和滑动t检验，得到近51年青藏高原地区的年强降水量在2012年发生突变；春季在2002年发生了突变；夏季在2012年发生突变；秋季在1999年发生突变。

Abstract: The Qinghai-Tibet Plateau possesses unique topographical features and surface characteristics. Investigating the characteristics of extreme precipitation variations in this area holds significant importance for local disaster risk reduction efforts and socio-economic development. In this study, we employed the CHM_PRE dataset to compute extreme precipitation thresholds using the percentile threshold method. These thresholds were then integrated with the extreme precipitation index R95P to derive corresponding values. Utilizing linear trend estimation, wavelet analysis, M_K abrupt change tests, and sliding t-tests, we conducted an in-depth analysis of the spatiotemporal patterns of extreme precipitation across the Qinghai-Tibet Plateau region. Our key findings are summarized as follows: 1) The average threshold for extreme precipitation in the Qinghai-Tibet Plateau is 12.43 mm, with a spatial distribution that decreases from southeast to northwest. The area with the highest threshold is located in Chayu County, Nyingchi City, while the areas with the lowest thresholds are mainly distributed in the Qaidam Basin and the Kunlun Mountain region. 2) The spatial distribution of strong precipitation in the Qinghai-Tibet Plateau during the annual and spring-summer-autumn seasons is similar to that of the spatial distribution of extreme precipitation thresholds, both decreasing from southeast to northwest. 3) Over the past 51 years, the annual and summer R95P on the Tibetan Plateau have shown significant interannual variability, with an overall upward trend, while other seasons exhibit less pronounced trends. 4) Over the past 51 years, the spatial distribution of the trend in strong precipitation amounts during the annual, spring, summer, and autumn seasons in the Qinghai-Tibet Plateau has been largely consistent, showing an increasing trend in areas where it is more prevalent than in areas where it is decreasing. A small part of the eastern and south-central regions of the Qinghai-Tibet Plateau generally show a decreasing trend, while the rest of the areas exhibit an increasing trend. 5) Over the past 51 years, the Tibetan Plateau’s annual and spring R95P cycles are primarily 17 years long. The summer cycle is similar, with an additional 26-year period. Autumn shows cycles of 25, 12, and 3 years, with the 25-year cycle being the most significant. 6) By conducting Mann-Kendall mutation tests and sliding t-tests, it was found that over the past 51 years, the annual heavy precipitation in the Qinghai-Tibet Plateau region underwent a mutation in 2012; the spring season experienced a mutation in 2002; the summer season had a mutation in 2012; and the autumn season had a mutation in 1999.