1956—2019年元谋干热河谷潜在蒸散发的变化及影响因素

The Variation and Influencing Factors of Potential Evapotranspiration in the Yuanmou Dry-Hot Valley from 1956 to 2019

为探究元谋干热河谷地区潜在蒸散发变化特征及其影响因子,通过应用彭曼蒙特斯模型、曼-肯德尔突变检验、气候倾向率和距平相关方法,分时段分析1956—2019年逐日气象要素值。结果表明:元谋干热河谷地区潜在蒸散发整体呈极显著下降的趋势,年度潜在蒸散发在1982年发生突变;各季潜在蒸散发变化明显,变化速率从大到小依次为3—5月、12月—次年2月、6—8月、9—11月;除1956—1982年12月—次年2月,1982—2019年9—11月、12月—次年2月潜在蒸散发有所增长外,剩下时段都呈减少趋势,1982年为各季的突变点。潜在蒸散发转折点为1982年;1982年前,年度潜在蒸散发距平占主导;1982年后,负距平占据主导,2008、2015年发生两次较大的波动。元谋干热河谷地区年潜在蒸散发变化主要取决于日照时间、气温和平均相对湿度;各季潜在蒸散发主要是由各气象要素共同作用的结果,且具有季节性差异;1982年以前,6—8月、9—11月潜在蒸散发的减少和12月—次年2月潜在蒸散发的增加仅与平均风速的减弱有关。

To explore the characteristics of potential evapotranspiration (PET) changes and their influencing factors in the Yuanmou dry-hot valley area, the Penman-Monteith model, Mann-Kendall mutation test, climate tendency rate, and anomaly correlation methods were applied to analyze daily meteorological elements from 1956 to 2019 in different time periods. The results showed that the overall trend of potential evapotranspiration in the Yuanmou dry-hot valley area exhibited a significant decrease, with a significant mutation occurring in annual PET in 1982. PET changes were significant in each season, with the change rates from highest to lowest being March to May, December to February of the following year, June to August, and September to November. Except that potential evapotranspiration increased from December to February of the following year from 1956 to 1982, from September to November of 1982 to 2019, and from December to February of the following year, the remaining periods showed a decreasing trend, and 1982 was the abrupt point of each season. The potential evapotranspiration turning point was 1982. Prior to 1982, annual PET was dominated by positive anomalies, while after 1982, negative anomalies predominated, with two significant fluctuations occurring in 2008 and 2015. The annual PET changes in the Yuanmou dry-hot valley area mainly depended on sunshine duration, temperature, and average relative humidity. The seasonal PET was mainly the result of the combined effects of various meteorological elements, with seasonal differences. Before 1982, the decrease in PET from June to August and September to November, and the increase in PET from December to February of the following year, were only related to the weakening of average wind speed.