Dynamic Changes of Drought Based on Vegetation Health Index and Its Response to Atmospheric Circulation Factors in China
In order to clarify the spatiotemporal variation characteristics of drought and the driving mechanism of at-mospheric circulation factors on drought in China,based on the remotely sensed vegetation health index(VHI)data from 1982 to 2020,the extreme-point symmetric mode decomposition(EPSMD)was used to analyze the dynamic variations of drought.The pixel-scale Mann-Kendall(PMK)was applied to identify the drought trend characteristics,and the cross wavelet technique was adopted to reveal the response relationship of drought to atmospheric circulation factors.The re-sults indicate that the drought showed an overall decreasing trend during 1982-2020 in China;The most severe drought during the research period occurred in 1989,with a relatively mild drought in summer(VHI=0.47)and a relatively se-vere drought in winter(VHI=0.38);The trend characteristic values of VHI in spring,summer,autumn,and winter were 0.70,0.48,0.59,and 0.48,and the most obvious drought mitigation trend occurred in spring;The El Niño-Southern Oscillation(ENSO)had the most significant impact on drought.The research results can provide reference for further research on the causes and mechanisms of drought in China.
droughtvegetation health indexatmospheric circulation factorcross waveletChina
NETL
NSTL
万方数据
