[Objective] The aim was to study the characteristics of the changes of extreme weather climate incidents such as severe drought in northwest and rainstorm in Xiji County of Ningxia. [Method] Precipitation anomaly perc...[Objective] The aim was to study the characteristics of the changes of extreme weather climate incidents such as severe drought in northwest and rainstorm in Xiji County of Ningxia. [Method] Precipitation anomaly percentage was applied to divide drought level and for statistics analysis. Seasonal index, linear tendency, and 5-years gliding average were used to reflect the trend of drought changes. The circulation wave of temporal sequence used polynomial expression to simulate the interannual variation scale. The positive part of the polynomial expression used bar chart to simulate interannual variation scale. [Result] The index of drought season from November to June was large. The general trend of annual drought was increasing. The drought of interannual scale was most serious around 1977, about 15 and 20 years. The drought in recent years went up. The general situation of drought, interannual scale and changes of interannual scales from March to May and from September to October were discussed. Based on the weather at 500 hPa, the first rain in Xiji and the drought-turning-into-rain situation were classified. [Conclusion]These may provide reference value to the prevention and mitigation of drought.展开更多
基金Supported by National Natural Science Foundation of China(40765003)Guyuan Meteorological Bureau Science and Technology Program in Ningxia~~
文摘[Objective] The aim was to study the characteristics of the changes of extreme weather climate incidents such as severe drought in northwest and rainstorm in Xiji County of Ningxia. [Method] Precipitation anomaly percentage was applied to divide drought level and for statistics analysis. Seasonal index, linear tendency, and 5-years gliding average were used to reflect the trend of drought changes. The circulation wave of temporal sequence used polynomial expression to simulate the interannual variation scale. The positive part of the polynomial expression used bar chart to simulate interannual variation scale. [Result] The index of drought season from November to June was large. The general trend of annual drought was increasing. The drought of interannual scale was most serious around 1977, about 15 and 20 years. The drought in recent years went up. The general situation of drought, interannual scale and changes of interannual scales from March to May and from September to October were discussed. Based on the weather at 500 hPa, the first rain in Xiji and the drought-turning-into-rain situation were classified. [Conclusion]These may provide reference value to the prevention and mitigation of drought.
