Abstract
Temporal and spatial variations in reference evapotranspiration (ET0) and aridity index (AI) can be used as important indexes for understanding climate change and its effects on ecosystem stability. Thus, in this work, we comprehensively investigated 71 meteorological stations in Northeast China from 1965 to 2017 to analyze the spatial-temporal variation and trend of ET0 and AI using the nonparametric Mann–Kendall test, the linear regression, and the Morlet wavelet methods. The results elucidated that ET0 for Northeast China as a whole exhibited a decrease at a rate of −1.97 mm/yr, AI declined at a rate of −0.01/yr during 1965–2017, and approximately 94% stations showed a decrease trend. Spatially, the high values of AI and ET0 were primarily at the western part of the study area except for the Heilongjiang province, and the stations showing low values were mainly distributed in the central and eastern part. The decreasing trends for AI were more obvious in the eastern part compared with the western part over the study region. The abrupt changes in AI occurred in 2005 and 2007, whereas only one abrupt change for ET0 occurred in 1995. For annual ET0, there were periods of 3, 7, 11, and 15 yr, and there existed periods of 1, 7, 11, and 13 yr for annual AI. The correlation coefficients implied wind speed and precipitation were the dominant meteorological factors resulting in the ET0 and AI decrease, respectively. Additionally, the change of the Indian summer monsoon index (ISMI) may also contribute to the weakened AI in the study area. Nevertheless, further investigation is still required to clarify the mechanisms for AI and ET0 variations in the future.
Highlights
Introduction e Fourth AssessmentReport (AR4) provided by the Intergovernmental Panel on Climate Change (IPCC) pointed that the variation of global climate could reach an unprecedented rate in the 21st century [1, 2]
Temporal and spatial variations in reference evapotranspiration (ET0) and aridity index (AI) can be used as important indexes for understanding climate change and its effects on ecosystem stability. us, in this work, we comprehensively investigated 71 meteorological stations in Northeast China from 1965 to 2017 to analyze the spatial-temporal variation and trend of ET0 and AI using the nonparametric Mann–Kendall test, the linear regression, and the Morlet wavelet methods. e results elucidated that ET0 for Northeast China as a whole exhibited a decrease at a rate of −1.97 mm/yr, AI declined at a rate of −0.01/yr during 1965–2017, and approximately 94% stations showed a decrease trend
It was reported that the aridity index (AI), frequently used to predict model scenarios that assess the extreme dry events, would benefit some agricultural areas [28], but AI has not been extensively employed except for Northwest China [20] and part of Tibetan Plateau [28], and the obtained results displayed that AI had a similar decreasing trend in Northwest China and significantly decreased by 0.04/10 yr in the central and eastern part of Tibetan Plateau from 1960 to 2012
Summary
Report (AR4) provided by the Intergovernmental Panel on Climate Change (IPCC) pointed that the variation of global climate could reach an unprecedented rate in the 21st century [1, 2]. A majority of studies have verified the effect of climate variation on ET0 and obtained fruitful results. It was reported that the aridity index (AI), frequently used to predict model scenarios that assess the extreme dry events, would benefit some agricultural areas [28], but AI has not been extensively employed except for Northwest China [20] and part of Tibetan Plateau [28], and the obtained results displayed that AI had a similar decreasing trend in Northwest China and significantly decreased by 0.04/10 yr in the central and eastern part of Tibetan Plateau from 1960 to 2012
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