Using Vegetation Health Index to Calculate Spatiotemporal Variation in Drought and Its Determinants in Inner Mongolia

Abstract

【Objective】 Drought is the most important abiotic stress affecting crop production in North China. Understanding its characteristics is essential to agricultural management. This paper is to investigate the spatiotemporal variation in drought from 1982 to 2020 and its underlying determinants in Inner Mongolia. 【Method】 The vegetation health index (VHI) measured from 1982 to 2020 was used to analyze the temporal and spatial characteristics of the drought. The cross-wavelet method was used to elucidate the effects of El Niño-Southern Oscillation (ENSO), Arctic Oscillation (AO), and sunspots on the drought. 【Result】 Drought in the studied region varied intra-annually, with the most severe droughts occurring in the summer. The main drought period is 8 years and 12 years. The central-northern region in Inner Mongolia experienced more severe droughts than other regions. Drought was more severe in the middle and northeast, while the south had seen a relief in drought. The region had witnessed a total eleven droughts in the studied period, with the most severe droughts occurring from October 1989 to March 1990. The worst and least severe droughts were in the 1980s and 2010s, respectively. Atmospheric circulation and sunspots correlated with the drought, with ENSO having the greatest influence and sunspots having the least impact on drought. 【Conclusion】 From 1982 to 2020, drought in Inner Mongolia had been worsening. ENSO influences drought most. These findings improve our understanding of the reasons behind the droughts and can help improve effective drought management in Inner Mongolia.

Keywords

• drought
• vegetation health index
• spatial-temporal evolution
• driving force analysis
• inner mongolia