Comparative Analysis of Drought Indicated by the SPI and SPEI at Various Timescales in Inner Mongolia, China

Zhifang Pei,Lei Wang,Shibo Fang,Wunian Yang

doi:10.3390/w12071925

Abstract

The global climate is noticeably warming, and drought occurs frequently. Therefore, choosing a suitable index for drought monitoring is particularly important. The standardized precipitation index (SPI) and the standardized precipitation evapotranspiration index (SPEI) are commonly used indicators in drought monitoring. The SPEI takes temperature into account, but the SPI does not. In the context of global warming, what are their differences and applicability in regional drought monitoring? In this study, after calculating the SPI and SPEI at 1-, 3-, 6-, and 12-month timescales at 102 meteorological stations in Inner Mongolia from 1981 to 2018, we compared and analyzed the performances of the SPI and SPEI in drought monitoring from temporal and spatial variations, and the consistency and applicability of the SPI and SPEI were also discussed. The results showed that (1) with increasing timescale, the temporal variations in the SPI and SPEI were increasingly consistent, but there were still slight differences in the fluctuation value and continuity; (2) due to the difference in time series, the drought characteristics identified by the SPI and SPEI were quite different in space at various timescales, and with the increase in timescale, the spatial distributions of the drought trends in Inner Mongolia were basically consistent, except in Alxa; (3) at the shortest timescale, the difference between the SPI and SPEI was the largest, and the drought reflected by the SPI and SPEI may be consistent at long timescales; and (4) compared with typical drought events and vegetation indexes, the SPEI may be more suitable than the SPI for drought monitoring in Inner Mongolia. It should be noted that the adaptability of the SPI and SPEI may be different in different periods and regions, which remains to be analyzed in the future.

Highlights

It is undeniable that the global climate is warming, and the accompanying extreme climate events are becoming increasingly frequent [1,2,3,4].Drought lasts for a long time and is the most serious meteorological disaster [5]
The variations of the standardized precipitation index (SPI) and standardized precipitation evapotranspiration index (SPEI) were similar at various timescales, but there were still slight differences in the fluctuation value and continuity, that is, they showed different drought frequencies and intensities
The drought reflected by the SPI and SPEI was slightly different in each month at various timescales, especially at

Summary

Introduction

It is undeniable that the global climate is warming, and the accompanying extreme climate events (including high temperatures, rainstorms, and droughts) are becoming increasingly frequent [1,2,3,4]. Drought lasts for a long time and is the most serious meteorological disaster [5]. Drought has had a severe impact on the environment and on economies around the world [6,7,8]. In arid and semiarid areas, serious drought even poses a long-term threat to human livelihoods [9,10]. In 2011, the worst drought in nearly 60 years occurred in Eastern Africa, resulting in water and food shortages, and 12.4 million people were affected by the famine, and nearly. Drought events will noticeably increase in the 21st

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