Drought characteristics in arid zone of middle Ningxia from 1960 to 2012 base on SPI index
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DOI:10.7606/j.issn.1000-7601.2017.02.41
Key Words: drought  standardized precipitation index  ensemble empirical mode decomposition  power spectrum analysis  arid zone of middle Ningxia
Author NameAffiliation
HU Yue Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China, Ningxia University, Yinchuan, Ningxia 750021, China
Key Laboratory for Restoration and Reconstruction of Degraded Ecosystem in Northwest China of Ministry of Education, Ningxia University, Yinchuan, Ningxia 750021, China 
DU Ling-tong Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China, Ningxia University, Yinchuan, Ningxia 750021, China
Key Laboratory for Restoration and Reconstruction of Degraded Ecosystem in Northwest China of Ministry of Education, Ningxia University, Yinchuan, Ningxia 750021, China 
HOU Jing Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China, Ningxia University, Yinchuan, Ningxia 750021, China
Key Laboratory for Restoration and Reconstruction of Degraded Ecosystem in Northwest China of Ministry of Education, Ningxia University, Yinchuan, Ningxia 750021, China 
LIU Ke Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China, Ningxia University, Yinchuan, Ningxia 750021, China
Key Laboratory for Restoration and Reconstruction of Degraded Ecosystem in Northwest China of Ministry of Education, Ningxia University, Yinchuan, Ningxia 750021, China 
ZHU Yu-guo Breeding Base for State Key Laboratory of Land Degradation and Ecological Restoration in Northwest China, Ningxia University, Yinchuan, Ningxia 750021, China
Key Laboratory for Restoration and Reconstruction of Degraded Ecosystem in Northwest China of Ministry of Education, Ningxia University, Yinchuan, Ningxia 750021, China 
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Abstract:
      With the purpose to provide scientific basis for regional agricultural development and disaster prevention and mitigation, by using the meteorological data from three in-situ stations during 1960 to 2012, the drought characteristics and variation trends in arid zone of middle Ningxia were studied by the method of standardized precipitation index (SPI), along with ensemble empirical mode decomposition (EEMD), power spectrum analysis and rescaled range analysis (R/S). The results showed that more than 30% of drought events, which happened in arid zone of middle Ningxia from 1960 to 2012, were moderate or even more serious drought. The multi-scale decomposition of drought period showed that there existed four time scales for the change cycle of different intensities of drought, i.e., 0.5 a for mild drought, 1 a for moderate drought, 3 a for severe drought, and 10 a for extreme drought. The EEMD analysis showed that the inter-annual fluctuation of drought was mainly derived from a 3.25-4 a period which contributed more than 65% to the whole variance, and followed by a 5.78-6.5 a period which contributed more than 14%. On the whole, the drought in arid zone of middle Ningxia is enhancing currently and this trend has a long-range dependence. Therefore, this region will keep a sustained drought in the future, but the characteristic of drought trend in various seasons is different.