黄土高原地区潜在腾发量模拟及时空变化

Simulating Potential Evapotranspiration and its Spatial and Temporal Changes of the Loess Plateau

运用世界粮农组织推荐的Penman-Monteith方程和1980-2008年黄土高原不同经纬度18个气象站气象要素观测数据，研究了黄土高原地区不同气象站点参照腾发量的时空变化特征。结果表明：1980～2008年黄土高原参照腾发量年平均值为874．74～1129．79mm，并随着纬度从北到南和经度从东到西有逐渐增加的趋势；20多年间绝大部分研究点的E瓦呈逐年增加趋势，其变化倾向率为4．04～48．25mm／10a，无论包头、横山、绥德、延安、洛川、固原、环县和临汾等地降雨量逐年减少，还是东胜、榆林、民和、靖远、海原和长治等地降雨量逐年增加，可见黄土高原的干旱化正在加剧。黄土高原各气象站点的参照腾发量年内最大值均出现在6、7月；5～8月的ET0占全年的比重为52．9％～59．2％，比重随着纬度的增加而减少。

The potential evapotranspiration （ET0） and its spatial and temporal changes are studied with Penman-Monteith equation recommended by FAO and meteorological observation data from dif- ferent latitude and longitude of 18 weather stations from 1980 to 2008 in the Loess Plateau. The resuits show that the mean annual ETo are 874. 74-1129.79ram, and gradually increase from north to south and from east to west in the area. The ETo of most weather stations was a rising trend and the tend to rate was 4.04-48.25mm/10a from 1980 to 2008, regardless of rainfall gradual decreasing year after year in Baotou, Hengshan, Suide, Yanan, Luochuan, Guyuan, Huanxian and Linfen, etc. , just the same as rainfall gradual increasing year after year in Dongsheng, Yulin, Minhe, Jingyuan, Haiyuan and Changzhi etc. , it is thus evident that drought are in process of exacerbation in the Loess Plateau. The annual maximum ETo appeared in June and July, the ETo from May to August accounted annually for 52.9%-59.2%, the proportion do gradually decrease with latitude increase.