陕西省近30年潜在蒸发量的时空变异规律

Spatial and Temporal Changes in Potential Evaporation in Recent Thirty Years in Shannxi Province

根据陕西省34个代表气象站点1988年—2017年逐日气象数据,分析以Penman公式计算的潜在蒸发量的时空变异规律及其对湿润指数的影响。结果表明:陕西省1988年—2017年平均的潜在蒸发量959 mm,从陕北(1020 mm)、关中(967 mm)到陕南(899 mm)逐渐降低,其差异主要在于空气动力学项。陕北潜在蒸发显著增大(25.9 mm/10 a),而关中和陕南潜在蒸发变化的趋势值分别只有12.2 mm/10 a和6.5 mm/10 a,相对湿度减小和风速增大引起的空气动力学项的增大(16 mm/10 a)是陕北潜在蒸发量显著增大的主要原因。受潜在蒸发变化影响,陕北和关中地表湿润指数增大但大气湿润指数减小,反映出两类不同过程的影响。

The spatial and temporal potential evaporation variations were calculated using Penman equation and their influences on wetness index were also evaluated,based on the daily data of 34 meteorological stations from 1988 to 2017.The mean annual potential evaporation during 1988—2017 is 959 mm,and the value decreases from Shanbei(1020 mm),Guanzhong(967 mm)to Shannan(899 mm)due to aerodynamic term.The annual potential evaporation exhibits a significant increasing trend(25.9 mm/10 a)in Shanbei,whereas the trends are much lower in Guanzhong and Shannan(12.2 and 6.5 mm/10 a,respectively).The significant increase in the aerodynamic component(16 mm/10 a)due to decrease in relative humidity and increase in wind speed is the main reason for the significant increase in potential evaporation in Shanbei.In Shanbei and Guanzhong,the surface wetness index increased whereas the atmospheric wetness index decreased,implying influences from large scale climate conditions.