了解陇中地区干湿状况,对进一步研究植被与气候变化和农业水资源管理有重要意义.基于陇中地区1961—2015年的地面气候资料日值数据集,应用彭曼蒙特斯模型(P-M模型)、滑动t检验、Morlet小波、主成分分析和薄盘样条插值等方法,对陇中地区近55 a潜在蒸散量(ET0)和干旱指数(AI,aridity index)的变化趋势进行了研究.结果表明:年际分布上ET0以上升趋势为主,AI整体上升趋势不显著,表明陇中地区近55 a气候趋于干旱;年内分布上ET0呈单峰型分布,AI则呈谷状分布;空间分布上陇中地区ET0和AI都呈有规律的从南向北依次增加的趋势,越往北气候越干;ET0在1975年、1983年和1997年发生了突变,AI则在1983年、1986年和2012年发生突变,ET0和AI的序列周期不尽相同.近55 a陇中地区气候趋于干旱.%Background,aim,and scope Central Gansu Province was the intersection of the Loess Plateau and Northwest China,located in arid and semi-arid northwest inland areas. The special climate conditions and the location of the area jointly determined that is a climate change sensitive area,both in the transitional zone of agriculture and animal husbandry,but also winter,spring wheat planting demarcation line. It was also a fragile ecological environment in Central Gansu Province. Understanding dry and wet conditions were of great significance for further study of vegetation and climate change and agricultural water resources management in Central Gansu Province. Materials and methods In this study,the change of potential evapotranspiration (ET0) and aridity index (AI) was analysed using observed meteorological data from nine stations in Central Gansu Province during the period from 1961 to 2015. Potential evapotranspiration was calculated based on Penmen-Monteith equation,the methods of moving t-test,morlet wavelet analysis,principal component analysis and thin plate spline interpolation,for analyzing the variation characteristics of potential evapotranspiration and aridity index over the past 55 years. Results The results showed that,for interannual distribution,displaying a drier climate trend in Central Gansu Province,potential evapotranspiration showed an obvious increasing tendency. The increasing tendency of aridity index was indistinctive. For seasonal distribution,potential evapotranspiration exhibited a unimodal type of distribution with peak value (131.35 mm) emerging in July,aridity index showed a valley-like type with minimum (?0.29) in September,respectively. For spatial distribution,potential evapotranspiration and aridity index presented that climate got drier from south to north. Abrupt changes of potential evapotranspiration primarily happened in 1975,1983 and 1997,however,aridity index primarily happened in 1983,1986,and 2012. The sequence periods of potential evapotranspiration and aridity index were different. Discussion In terms of the rate of potential evapotranspiration change,the amplitude of the Central Gansu Province is higher than that of the whole country and the northwest,lower than that of China's southwest and north,indicating that there were obvious regional differences. In the past 55 years,the drought index has been rising slowly in Central Gansu Province. The changes of potential evapotranspiration,air temperature and precipitation may be the main reasons for the periodical change and mutation of drought index. Conclusions In the past 55 years,the potential evapotranspiration risen mostly,and the overall upward trend of the aridity index was not obvious. According to the change trend of two indicators,the climate showed a trend of drought in Central Gansu Province. In terms of spatial distribution,potential evapotranspiration and aridity index tended to increase from south to north,and the climate became dry from south to north one by one. Among them,Jingtai was the driest and Minxian was relatively humid. The sequence periods of potential evapotranspiration and aridity index were different. El Ni?o events was main factor affecting aridity index,nevertheless,El Ni?o events,atmospheric circumfluence and sunspot activity were vital factor for potential evapotranspiration in Central Gansu Province. Recommendations and perspectives The trend of potential evapotranspiration and aridity index was quantitatively analyzed,to reveal the relationship between potential evapotranspiration and aridity index,understanding the extent and distribution of wet and dry conditions in the area. So as to improve the ecological environment,adjust the agricultural structure and regional economic development.
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