Evolutional Characteristics of Regional Meteorological Drought and Their Linkages with Southern Oscillation Index across the Loess Plateau of China during 1962–2017

Ming Li,Xurong Chai,Guiwen Wang,Lianzhi Zhang,Fuqiang Cao

doi:10.3390/su12187237

Abstract

The Loess Plateau of China (CLP) is located in the transition zone from a semi-humid climate zone to semi-arid and arid climate zones. It is influenced by the westerly circulation, plateau monsoon, and East Asian monsoon circulation, and the drought disasters across the CLP have obvious regional characteristics. In this study, climate regionalization was performed by a spatial hierarchical cluster approach based on the gridded datasets of monthly precipitation across the CLP from 1961 to 2017. Then, the standardized precipitation index (SPI) was used to explore the temporal evolution of regional meteorological droughts. Finally, wavelet methods were used to investigate the drought cycles in each homogeneous subregion and the linkages between SPI and the Southern Oscillation Index (SOI). The results show that: (1) Spatially, the CLP can be divided into four homogeneous regions, namely, Ordos Plateau semi-arid area (Region I), Northern Shanxi hilly semi-humid area (Region II), Longzhong plateau cold-arid area (Region III), and Fenwei Plain and Shaanxi-Shanxi hilly semi-humid area (Region IV). (2) There are apparent differences in the temporal evolution of meteorological droughts in different subregions, but two wet periods from the 1960s to 1980s and 2010s, and a drought period in the 1990s, can be found in each subregion. (3) There is a significant drought cycle of 3–8 years in the four subregions, and the first main cycles of drought variation are not completely consistent. (4) The linkages between SPI and SOI are time- and space-dependent and the phase differences are dominated by in-phase. The strongest correlations between the two time series occur in the 1980s in the four subregions. The results of this research have important implications for the establishment of drought monitoring programs in homogeneous climate regions, and informed decision making in water resource management.

Highlights

Drought is a common, recurring phenomenon that occurs in all climatic zones, from wet to dry [1]
(4) The linkages between standardized precipitation index (SPI) and Southern Oscillation Index (SOI) are time- and space-dependent and the phase differences are dominated by in-phase
Previous research has been carried out on the relationships between precipitation and large-scale climate indices (e.g., Southern Oscillation Index (SOI) and Pacific Decadal Oscillation (PDO)) globally, and the results revealed that rainfall variations are affected by the El Niño and La Niña phenomena [32,33,34,35]

Summary

Introduction

Drought is a common, recurring phenomenon that occurs in all climatic zones, from wet to dry [1]. Many scholars have used the SPI to study the spatio-temporal characteristics of droughts around the world [8,9,10,11,12]. The main criticism of the SPI is that it only addresses the effects of precipitation on drought conditions. It does not take into account other influencing variables such as temperature, wind speed, and soil water holding capacity [7,16]. Several studies have demonstrated that precipitation is the decisive variable that affects the onset, duration, intensity, and end of droughts [7,17]

Methods

Results

Conclusion