岷山主峰两侧区域降水类型及年际变化的差异性

Differences in Precipitation Type and Interannual Variation between the Two Sides of the Min Mountains

  • 摘要: 掌握山区降水特征对研究当地气候、环境变化和自然灾害防御有重要意义。为研究岷山主峰两侧区域的降水特征和变化差异,本文基于西侧松潘县和东侧平武县1961—2020年日降水量数据,利用湿球温度动态阈值法、极端降水指数、后向轨迹模拟等方法,分析了岷山主峰东西两侧区域的降水特征及变化。结果表明:(1)岷山主峰东侧降水量高于西侧,但降水日数少;西侧降水由小雨(雪)、中雨(雪)、大雨(雪)和暴雪组成,降水集中于5—10月;东侧降水在年内分布呈“单峰型”,大雨和暴雨比西侧多,降水集中于5—9月。(2)西侧和东侧降水量整体分别呈不显著的增加和减少趋势;但东侧小雨和大雨分别有显著的增加和减少,且在近20 a变化最明显;西侧强降水量显著增加而东侧显著减少,是导致两侧降水气候变化差异的重要原因。(3)东西两侧区域降水在近60 a无显著突变性,但东侧大雨以上降水在21世纪以来显著减少;整体而言,岷山主峰两侧降水特征和气候变化响应有较大差异,未来应关注较高量级降水的发生规律和极端降水事件的变化。

     

    Abstract: Understanding the characteristics of precipitation in mountainous areas is of great significance for studying local climate, eco-environmental changes, and natural disaster prevention. To investigate precipitation characteristics and variations between the two sides of the main peak of the Min Mountains, this study analyzes regional precipitation characteristics and variations based on daily precipitation data from 1961 to 2020 in Songpan County (west side) and Pingwu County (east side). Multiple approaches are employed, including the dynamic wet-bulb temperature threshold algorithm, standardized extreme precipitation indices, and backward air mass trajectory simulation. The results indicate that: (1) The precipitation on the eastern side of the Min Mountains is higher than that on the western side, but the number of precipitation days is fewer. The precipitation in the west consists of light rain/snow, moderate rain/snow, heavy rain/snow and blizzards, with the precipitation concentrated from May to October. Precipitation on the east side shows a unimodal annual distribution, heavy rain and rainstorm frequencies are notably higher than those on the western side, and precipitation mainly occurs from May to September. (2) Overall, precipitation on the west side of the Min Mountains shows a non-significant increasing trend, whereas total precipitation on the east side shows a non-significant decreasing trend. However, light rain and heavy rain in the east have significantly increased and decreased, respectively, and the changes have been most pronounced in the past 20 years. The significant increase in heavy precipitation on the west side and the significant decrease on the east side are important reasons for the differences in precipitation responses to climate change between the two sides of the Min Mountains. (3) There has been no significant abrupt change in precipitation on either side of the Min Mountains over the past 60 years, but heavy and extreme precipitation on the east side has decreased significantly since the start of the 21st century. Overall, there are significant differences in precipitation characteristics and climate change responses between the two sides of the Min Mountains. In the future, attention should be paid to the occurrence patterns of high-magnitude precipitation and changes in extreme precipitation events.

     

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