Open AccessVariations of the Reference Evapotranspiration and Aridity Index Over Northeast China: Changing Properties and Possible Causes
Author(s) -
Liguo Cao,
Zhengchao Zhou
Publication year - 2019
Publication title -
advances in meteorology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.482
H-Index - 32
eISSN - 1687-9317
pISSN - 1687-9309
DOI - 10.1155/2019/7692871
Subject(s) - evapotranspiration , aridity index , climatology , arid , geography , precipitation , china , index (typography) , physical geography , climate change , trend analysis , environmental science , morlet wavelet , wavelet , meteorology , mathematics , wavelet transform , statistics , geology , ecology , discrete wavelet transform , oceanography , archaeology , artificial intelligence , world wide web , computer science , biology , paleontology
Temporal and spatial variations in reference evapotranspiration (ET 0 ) 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 ET 0 and AI using the nonparametric Mann–Kendall test, the linear regression, and the Morlet wavelet methods. The results elucidated that ET 0 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 ET 0 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 ET 0 occurred in 1995. For annual ET 0 , 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 ET 0 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 ET 0 variations in the future.