秦岭南北潜在蒸散量时空变化及突变特征分析

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（ET0）。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ET0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ET0为9642 mm，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ET0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52 a ET0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ET0下降更明显，春季大部分（78%）站点ET0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ET0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ET0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ET0减少的主导因素，风速和日照时数的下降导致夏季和冬季ET0减少，气温上升导致春季和秋季ET0增加或整体保持稳定

SPATIAL-TEMPORAL VARIATIONS AND MUTATIONS OF POTENTIAL EVAPOTRANSPIRATION IN THE NORTHERN AND SOUTHERN REGIONS OF THE QINLING MOUNTAINS

Potential evapotranspiration（ET0）， as an estimate of the evaporative demand of the atmosphere， has been widely discussed in researches on irrigation management， crop water demand and predictions in ungauged basins Analysis of ET0spatial and temporal variation is the basic research on the impact of climate change on water resources， and also is important to the optimal allocation of agricultural water resources In this study， based on the daily data from 54 meteorological stations in Northern and Southern Regions of the Qinling Mountains between 1960 and 2011， with the help of FAO Penman Monteith formula， ET0 was calculated By using the Spline interpolation method， climate trend rate， Pettitt abrupt change point detection， correlation analysis and other methods， we analyzed the distribution and temporal and spatial variation characteristics of ET0 as well as the meteorological elements which influenced evapotranspiration The results are as follows. （1）Average annual ET0 was 9642 mm， with the spatial distribution pattern of higher in east and lower in west According to the size of evapotranspiration， the order was northern and southern region of the Qinling Mountain， the Han River Basin， the Ba Wu Valley ET0 in four seasons had the same distribution characteristics as the annual ET0， the order was summer， spring， autumn and winter （2）According to the percent of stations with decreasing trend accounted for the whole stations， the order was the Han River Basin， southern slope of the Qinling Mountain， the Ba Wu Valley， northern region of the Qinling Mountain The decreasing trend was more obvious in southern region than that in northern region ET0 of most stations in spring， which accounted for 78%， increased while ET0 in summer， which accounted 91%， decreased significantly No obvious increasing or decreasing trend was founded in autumn or winter The departure of ET0 in summer and annual between 1960s and 1970s was positive while negative between 1980s and 2000s; ET0 in autumn experienced negative and positive departure in the past 50 years， which appeared alternatively ET0 in spring decreased in 1960s， then increased until 1980s， since then presented a downward trend， finally increased significantly in 2000s; ET0 in winter fluctuated in the past 50 years， the order was positive， positive， negative， positive and negative The spatial and temporal distribution of ET0 illustrated the difference of ET0 in different latitude zone under the background of climate change On the other hand， it could also be concluded that complicated terrain could influenced the distribution of temperature， precipitation， wind speed and other meteorological factors， which would finally influenced ET0. （3）The abrupt change of annual and spring ET0 happened in 1993 or between 1979 and 1981， while ET0 of 85% stations in summer changed in 1979 There was no obvious abrupt change points in autumn or winter （4）Precipitation and ET0 of 70% stations in summer presented an negative correlation relationship， as for autumn the number accounted for 76% Sunshine hour， maximum temperature， average temperature and wind speed correlated positively with ET0， which reached 001 significant level According to size of correlation coefficient， the order was sunshine duration， maximum temperature， average temperature and wind speed The decrease of sunshine duration and wind speed leaded to ET0 decreasing in summer and winter while temperature increasing caused ET0 increased in spring and autumn 