近52a西南地区潜在蒸散发时空变化特征

潜在蒸散发对水资源评价和气候变化均具有重要意义。采用Penman-Monteith公式和气象观测资料计算了中国西南地区90个气象站的潜在蒸散发,并采用多种统计方法分析了潜在蒸散发的时空变化特征。结果表明:(1)西南地区近52a的平均潜在蒸散发为3 209.8 mm,其中云南省潜在蒸散发最高(3 664.7 mm),其次为四川省(3 015.0 mm)、重庆市(2 972.4 mm)、贵州省(2 958.0 mm)。四季潜在蒸散发空间分布特征与年不同,从大到小排序为夏季,春季,秋季,冬季。(2)西南地区整体呈增加趋势(0.9 mm/10 a),其中31个站点呈减少趋势(p0.1),17个站点呈增加趋势(p0.1),其余站点变化趋势不显著。大部分站点春季(55.6%)和夏季(63.3%)呈减少趋势,秋季(62.2%)和冬季(58.9%)则呈增加趋势。(3)经MannKendall突变检验,该区整体潜在蒸散发的突变时间为1995年(p0.05);单个站点突变检验显示,76个站点发生突变,突变年份集中于1980s,未发生突变的站点主要分布于青藏高原东缘。整体上看,近52a来西南地区潜在蒸散发略呈增加趋势,并存在突变点,但部分站点存在相反的变化趋势,这和复杂的地形环境和气候特征有较大关系,体现出西南地区水文气象变化的独特性。

SPATIAL AND TEMPORAL VARIATIONS OF POTENTIAL EVAPOTRANSPIRATION IN SOUTHWESTERN CHINA FROM 1962 TO 2013

Potential evapotranspiration (PET) is crucial to water resources assessment and climate change.Based on the Penman-Monteith equation proposed by Food and Agriculture Organization (FAO) and daily meteorological data of 90 meteorological stations in Southwestern China,daily potential evapotranspiration at 90 meteorological stations was calculated.Then,various statistical methods were used to analyze its spatial and temporal variations.The results showed that the mean annual potential evapotranspiration in the whole Southwestern China during the recent 52 years was 3 209.8 mm,the highest potential evapotranspiration value was observed in Yunnan Province (3 664.7 mm),followed by Sichuan Province (3 015.0 mm),Guizhou Province (2 958.0 mm),and Chongqing Municipality (2 972.4 mm).PET in summer was the highest,followed by spring,autumn and winter.Distribution characteristics of four seasons are different from that of annual mean.Moreover,the linear changing trend of potential evapotranspiration in Southwestern China was 0.9 rnm/10a.There are 31 stations showing a decreasing trend (p＜0.1) and 17 stations showing an increasing trend (p＜0.1).Decreasing PET in spring and summer was found at 55.6％ and 63.3％ of all stations,respectively.While increasing PET in autumn and winter was found at 62.2％ and 58.9％ of all stations,respectively.Through the abrupt change test and moving t-test,a significant abrupt point was found in 1995 for PET of Southwestern China (p＜0.05).Among the 90 stations,abrupt points of 76 stations concentrated in the 1980s.In additional,15 stations had no abrupt points which mainly distributed in the eastern margin of the Tibetan Plateau.On the whole,PET in Southwestern China increased slightly from 1962 to 2013.However,some regions appeared an opposite trend.The abrupt test also showed the same pattern.Complex terrain environment and climate characteristics are the main factors reflecting the unique feature of hydrometeorology changes in Southwestern China.