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Characteristics and Drivers of Reference Evapotranspiration in Hilly Regions in Southern China
- Liu, Youcun, Liu, Yan, Chen, Ming, Labat, David, Li, Yongtao, Bian, Xiaohui, Ding, Qianqian
- Water 2019 v.11 no.9
- El Nino, altitude, climate, data collection, evapotranspiration, latitude, longitude, meteorological data, mutation, relative humidity, solar radiation, summer, temperature, winter, China
- This paper has adopted related meteorological data collected by 69 meteorological stations between 1951 and 2013 to analyze changes and drivers of reference evapotranspiration (ET<inf>0</inf>) in the hilly regions located in southern China. Results show that: (1) ET<inf>0</inf> in southern China’s hilly regions reaches its maximum in summer and its minimum in winter, and that the annual ET<inf>0</inf> shows an increasing trend. ET<inf>0</inf> happened abrupt change due to the impact of abrupt meteorological variables changes, and the significant year of mutation were 1953, 1964 and 2008. Most abrupt changes of ET<inf>0</inf> in meteorological stations occurred in the 1950s and 1960s. (2) The low value of ET<inf>0</inf> was mainly captured in high-altitude areas. Spatially, the ET<inf>0</inf> in the east was higher than that in the west. With the exception of a handful of stations, the trend coefficients of ET<inf>0</inf> were all positive, exhibiting a gradual rise. Changes in ET<inf>0</inf> in the east were much more sensitive than that in the west. Since ET<inf>0</inf> was affected by the cyclical changes in relative humidity, short-period oscillations were observed in all these changes. (3) In general, the ET0 was negatively correlated with relative humidity, and positively correlated with temperature and sunshine percentage. ET<inf>0</inf> is most sensitive to changes in average temperature, with a sensitivity coefficient of 1.136. ET<inf>0</inf> showed positive sensitivity to average temperature and sunshine hours, which were notable in the northeastern, and uniform in the spatial. ET<inf>0 </inf>showed negatively sensitivity to relative humidity, and the absolute value of sensitivity coefficient in the northwestern is smaller. The highest contribution to ET<inf>0</inf> is the average temperature (6.873%), and the total contribution of the four meteorological variables to the change of ET<inf>0</inf> is 7.842%. The contribution of average temperature, relative humidity, and sunshine hours to ET<inf>0</inf> is higher in the northern and eastern, northern, northern and eastern areas, respectively. Climate indexes (Western Pacific Index (WP), Southern Oscillation Index (SOI), Tropical Northern Atlantic Index (TNA), and El Niño-Southern Oscillation (ENSO)) were correlated with the ET<inf>0</inf>. In addition, the ET<inf>0</inf> and altitude, as well as the latitude and longitude were also correlated with each other.