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Increasing drought has been observed by SPEI_pm in Southwest China during 1962–2012

Wang, Zhaoli, Li, Jun, Lai, Chengguang, Huang, Zeqin, Zhong, Ruida, Zeng, Zhaoyang, Chen, Xiaohong
Theoretical and applied climatology 2018 v.133 no.1-2 pp. 23-38
basins, drought, dry environmental conditions, equations, evapotranspiration, plateaus, spatial variation, temporal variation, time series analysis, wavelet, China
Drought is regarded as an environmental disaster that has significantly impacted on economic and social development in recent decades, particularly in Southwest China (SWC). Here, we presented an analysis of spatiotemporal variations of meteorological drought in SWC. We computed the standardized precipitation evapotranspiration index using the Penman–Monteith equation (SPEI_pm) and explored spatiotemporal variational evolution of drought in SWC during 1962–2012 utilizing the Mann–Kendall test, continuous wavelet transform (CWT), and rotated empirical orthogonal function (REOF). We also analyzed the relationship between the rotated principal component time series (RPCs) and the 74 circulation indices. The results showed that (1) SWC displayed a dry trend at annual and seasonal scale with a 2–4-year significant period. The SWC can be divided into six sub-climate regions with different aridity and wetness features. (2) Among the six regions, the Eastern Yunnan Plateau showed an obvious dry trend while Hanzhong Basin and the Eastern Mountain Areas showed a wet trend that was not significant. There were 2–8-year periods of oscillation in general within the variation of the six regions. (3) The indices of the strength of the polar vortex in Asia (APVA) may affect the drought evolution of the whole study area. The change of drought in Eastern Yunnan Plateau and Sichuan Basin may be associated with Tibetan Plateau High.