关键词: 水氮效率, 水氮效率

Abstract: Based on surface observation data of meteorological stations in Hunan Province from 1971 to 2012, the spatiotemporal variability of annual pan evaporation (PE) and the major meteorological factors were analyzed by using linear regression, EOF, correlation analysis and relative weighting method. The results showed that: the annual mean total PE in Hunan Province presented an insignificant decreasing trend in the past 42 years; the annual mean PE had an evident interdecadal fluctuation in most regions, it had significant decreasing trends in the central of Hunan and most areas of east Hunan, but significant increasing trends in eastern part of southwest Hunan, and there was no significant trends in other areas. In addition, there were significant relationship between PE with sunshine duration, precipitation, mean air temperature, diurnal temperature range and vapor pressure deficit. PE had the highest positive correlation with sunshine duration and the highest negative correlation with precipitation; furthermore, the leading factors in regions with decreasing PE and increasing PE were the reduction in sunshine duration and precipitation, respectively.