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根据秦岭南北54个气象站1960～2011年逐日数据,利用FAO Penman-Monteith公式计算出各站的潜在蒸散量(ET0)。采用样条曲线插值法(Spline)、气候倾向率、Pettitt突变点检测、相关分析等方法对该区ET0的时空变化特征以及影响其变化的气象要素进行了分析。结果表明:(1)研究区多年平均ET0为964.2mm,空间分布呈东高西低格局。各分区按其大小排序为秦岭以北>秦岭南坡>汉水流域>巴巫谷地。四季ET0分布特征与年尺度上的结论基本一致,4个季节按其大小排序为夏季>春季>秋季>冬季;(2)近52aET0下降的站点占本区站点总数的比例排序为汉水流域>秦岭南坡>巴巫谷地>秦岭以北,秦岭以南的广大地区相对于秦岭以北ET0下降更明显,春季大部分(78%)站点ET0上升,夏季绝大部分(91%)站点显著下降,秋季和冬季变化趋势不明显;(3)年尺度和春季ET0突变点集中出现在1979～1981年和1993年,夏季85%的站点发生了突变,其中89%发生于1979年,秋季和冬季的突变特征无明显规律可言;(4)夏季降水与潜在蒸散量变化趋势的空间分布整体上呈相反趋势,呈相反趋势的站点占站点总数的70%,秋季则达到76%。23个站点中绝大多数ET0与日照时数、最高气温、平均气温和平均风速呈显著水平(P<0.01)的正相关关系,相关系数排序为日照时数>最高气温>平均气温>平均风速。风速和日照时数的降低是导致秦岭南北ET0减少的主导因素,风速和日照时数的下降导致夏季和冬季ET0减少,气温上升导致春季和秋季ET0增加或整体保持稳定。
Based on daily data of 54 weather stations in north and south Qinling from 1960 to 2011, potential ET (EOS) of each station was calculated by FAO Penman-Monteith formula. The spatiotemporal variation of ET0 and its meteorological elements were analyzed by spline, climate tendency, Pettitt mutation detection and correlation analysis. The results showed that: (1) The multi-year average ET0 in the study area was 964.2 mm, and the spatial distribution showed an east-west high pattern. According to the size of the sub-region, the order is north of Qinling Mountains> southern slope of Qinling Mountains> Han River Valley> Pakistan Witch Valley. The distribution characteristics of ET0 in the four seasons are basically the same as those on the annual scale. Four seasons are sorted by their size in summer> spring> autumn> winter; (2) The south slope of Qinling Mountains> Wugu Valley> The area south of Qinling Mountains and south of Qinling Mountains declined more obviously than ET0 north of Qinling Mountains. The ET0 of most sites (78%) increased in spring, and most sites (91%) dropped significantly in summer (3) At the annual scale and the spring ET0 mutation occurred in 1979-1981 and 1993, 85% of the sites in summer changed, of which 89% occurred in 1979, autumn and winter (4) The spatial distribution of the trend of summer precipitation and potential evapotranspiration shows the opposite trend as a whole. The stations with opposite trend account for 70% of the total number of stations and 76% in autumn. The correlation between ET0 and sunshine time, maximum temperature, average temperature and mean wind speed was significant (P <0.01) at 23 sites, and the correlation coefficient was the sunshine hours> the highest temperature> the average temperature> the average wind speed . The decrease of wind speed and sunshine duration was the main factor leading to the decrease of ET0 in the north and south of Qinling Mountains. The decrease of wind speed and sunshine duration resulted in the decrease of ET0 in summer and winter, and the increase of temperature caused the increase of ET0 in spring and autumn or overall stability.