关中地区参考作物蒸发蒸腾量时空变化特征及主要因子分析

Spatiotemporal Variation in Reference Evapotranspiration over Guanzhong Region and Its Determinants

【目的】充分认识关中地区参考作物蒸发蒸腾量(ET_(0))时空变化特征及其主要影响因子。【方法】使用1980-2019年关中地区43个气象观测站逐日气象资料,结合Penman-Monteith(P-M)模型、反距离权重、逐步回归分析和通径分析等方法,研究1980-2019年关中地区ET_(0)时空变化特征及其主要影响因子。【结果】最高气温(Tmax)、最低气温(Tmin)、平均气温(T)呈升温趋势,上升幅度处于1.68~2.85℃之间;相对湿度(RH)呈下降趋势;日照时数(SSD)整体变化较小;平均风速(WS)则呈减小趋势;气象因子空间分布因海拔、地形不同而表现出差异性;关中地区多年平均ET_(0)为959 mm,整体呈增加趋势,增加速率为1.43 mm/a;ET_(0)空间分布差异较大,多年平均ET_(0)处于852~1099 mm之间,由东北向西南递减,关中地区ET_(0)季节性差异明显;影响关中地区ET_(0)的气象因子排序为:T>SSD>RH>WS;SSD、T、WS与ET_(0)正相关;RH与ET_(0)负相关。【结论】关中地区ET_(0)在时间上呈增加趋势,空间上由东北向西南递减;4个主要因子对ET_(0)的影响由大到小依次为T、SSD、RH、WS。

【Background and objective】Evapotranspiration is an important component in the hydrological cycle in terrestrial ecosystems,and it is often calculated based on reference evapotranspiration(ET_(0))multiplied by a crop coefficient.In this paper,we analyzed the spatiotemporal variation of ET_(0)and its underlying determining factors in Guanzhong region.【Method】Daily meteorological data measured from 1980 to 2019 from 43 weather stations in the region were used to calculate ET_(0)using the Penman-Monteith model.Spatiotemporal change in ET_(0)and its underlying determinants were calculated using the inverse distance weight,stepwise regression analysis and path analysis.【Result】The maximum air temperature(T_(max)),minimum air temperature(T_(min))and average air temperature(T)had been increasing at rates of 1.68~2.85℃,while the average relative humidity(RH)and wind speed(WS)had been declining in the studied period.In contrast,there was no noticeable change in sunshine hours(SSD).The meteorological factors varied spatially due to the difference in altitude and topography.The annual average ET_(0)from 1980 to 2019 was 959 mm,and had been increasing at a rate of 1.43 mm/a.Across the region,ET_(0)varied from 852~1099 mm in 1980—2019,and decreased from the northeast to the southwest.In all regions,seasonal differences in ET_(0)were noticeable.The influence of meteorological factors on ET_(0)was ranked in the order of T>SSD>RH>WS.We also found that ET_(0)was positively correlated with SSD,T,and WS and negatively with RH.【Conclusion】Temporally,ET_(0)in Guanzhong region had been increasing from 1980—2019.Spatially,it decreased from the northeast to the southwest.The meteorological factors that affected ET_(0)most were T,SSD,RH and WS,in descending order.