Drought characteristics analysis of Gansu in recent 50 years based on meteorological drought composite index
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DOI:10.7606/j.issn.1000-7601.2017.01.32
Key Words: Gansu province  MCI index  characteristics of drought
Author NameAffiliation
CHENG Qing-yan Key Laboratory of Arid Climatic Change and Disaster Reduction of Gansu Province/Key Laboratory of Arid Climatic Change and Disaster Reduction of China Meteorological Administration, Institute of Arid Meteorology, China Meteorological Administration, Lanzhou, Gansu 730020, China
Climate Center of Northwest Region, Lanzhou, Gansu 730020, China 
GAO Xiao-qing Key Laboratory of Land Surface Process and Climate Change in Cold and Arid Regions, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, Gansu 730020, China 
LIN Shu Key Laboratory of Arid Climatic Change and Disaster Reduction of Gansu Province/Key Laboratory of Arid Climatic Change and Disaster Reduction of China Meteorological Administration, Institute of Arid Meteorology, China Meteorological Administration, Lanzhou, Gansu 730020, China
Climate Center of Northwest Region, Lanzhou, Gansu 730020, China 
ZHAO Hong-yan Key Laboratory of Arid Climatic Change and Disaster Reduction of Gansu Province/Key Laboratory of Arid Climatic Change and Disaster Reduction of China Meteorological Administration, Institute of Arid Meteorology, China Meteorological Administration, Lanzhou, Gansu 730020, China
Climate Center of Northwest Region, Lanzhou, Gansu 730020, China 
YANG Su-hua Key Laboratory of Arid Climatic Change and Disaster Reduction of Gansu Province/Key Laboratory of Arid Climatic Change and Disaster Reduction of China Meteorological Administration, Institute of Arid Meteorology, China Meteorological Administration, Lanzhou, Gansu 730020, China
Climate Center of Northwest Region, Lanzhou, Gansu 730020, China 
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Abstract:
      Based on the data of MCI value during 1961—2010 from the national climate center, we worked for the drought characteristics in Gansu province. The study shows that: the drought occurred in higher frequency in spring (55.4%) and summer (55.0%), and relatively lower frequency in autumn (41.1%) and winter(46.3%). The large-scale drought in the whole area occurred mostly in summer and autumn, but least in winter. Moreover, the drought-suffered area is still extended in various seasons during the latest 50 years. Considering frequency and severity of drought, longer different grades of drought occur in spring, and easily develop to the severe drought. In summer and winter, light and mederate drought easily happens in large area, but rarely severe drought occurs. Drought in autumn is mild with short duration Compared regional difference of drought occurrence, Gannan area has less drought, while eastern part of Hexi, northern part of Longzhong and southern part of Longnan have higher drought frequency. In the latest 50years, annual average and daily mean of drought duration, drought-suffered stations proportion and drought intensity were fluctuant without a significant sense. Drought intensity is the strongest in spring and the weakest in autumn. The significant negative correlation was observed between dr ought intensity and rainless days.