Abstract
Evidence that the pan evaporation or reference evapotranspiration (ET0) as the indicator of atmospheric evaporation capability have decreased along with the continuous increase in temperature over the past decades (coined as âevaporation paradoxâ) has been reported worldwide. Here, we provide a nationwide investigation of spatiotemporal change of ET0 using meteorological data from 602 stations with the updated data (1961â2011). In addition, we explore the trigger mechanism by quantitative assessment on the contribution of climatic factors to ET0 change based on a differential equation method. In despite of different shift points regionally, our results suggest that the ET0 generally present decadal variations rather than monotonic response to climate change reported in previous studies. The significant decrease in net radiation dominate the decrease in ET0 before early 1990s in southern regions, while observed near-surface wind speed is the primary contributor to the variations of ET0 for the rest regions during the same periods. The enhancements of atmospheric evaporation capability after early 1990s are driven primarily by recent relative humidity limitation in China. From a continental scale view, as highly correlating with to Pacific Decadal Oscillation, the shift behaviors of ET0 is likely an episodic phenomenon of the ocean-atmosphere interaction in earth.
Highlights
Evidence that the pan evaporation or reference evapotranspiration (ET0) as the indicator of atmospheric evaporation capability have decreased along with the continuous increase in temperature over the past decades has been reported worldwide
The whole China is always divided into eight climatic regions according to the latitude and longitude, and the climate regions are roughly coincide with the socioeconomic division[13,23]
The percentages of variance of the new set of rotated empirical orthogonal function (REOF) modes generated by rotating the first eight loading vectors of the initial EOFs (Table S1) and correspondent isolines of the loading factor values (Figure S1) suggest that Mainland China can be categorized into eight homogenous regions (Fig. 1) by REOF analysis based on the annual ET0 series from 602 stations for 1961â2011
Summary
Evidence that the pan evaporation or reference evapotranspiration (ET0) as the indicator of atmospheric evaporation capability have decreased along with the continuous increase in temperature over the past decades (coined as âevaporation paradoxâ) has been reported worldwide. Along with significantly increasing near-surface air temperatures, decreasing pan evaporation (ETpan), potential evapotranspiration (ETp) and reference evapotranspiration (ET0) have been reported in many regions worldwide and continuously documented by many studies since the first publication by Peterson et al in 19953. This phenomenon has been denoted as the âevaporation paradoxâ[4]. The goal of this study is to examine whether the âevaporation paradoxâ is still true by investigating the response of ET0 to changing climatic environment based on recently updated nationwide observation in China. The driving mechanisms under natural large atmosphere system are explored by identifying the correlation between changes in ET0 and Pacific Decadal Oscillation
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