Spatio-temporal Variation Of Meteorological Drought In The Jing-jin-ji Region In Recent 56years

In the context of global warming,the frequency of extreme weather and climate events are increased,which leads to an increased in the frequency of natural disasters,and it is particularly important to solve the problem of global natural disasters.The frequency of drought is one of the most serious problems,which has become a global problem.Based on temperature and precipitation data of 88 lattice points in Jing-Jin-Ji region in recent 56 years,this study is to analyzes the applicability of the precipitation anomaly percentage(Pa),standardized precipitation evapotranspiration index(SPEI),standardized precipitation index(SPI)and Z index in Jing-Jin-Ji region,and then select the most appropriate drought index,based on this,useing the climate tendency rate,Mann-Kendall test and IDW to analyse spatial and temporal variation characteristics and their casue for meteorological drought in Jing-Jin-Ji region.Finally,we uses gray prediction model GM(1,1),which is based on gray system theory,to forecast the future drought.The specific conclusions are as follows:(1)Four kinds of drought indices showed large difference in spatial and temporal variation.SPI,precipitation anomaly percentage(Pa)and HL index of drought indices have unobvious increasing trend,but SPEI shows a decreasing trend.Compared with the actual situation,the drought reflected by Pa and SPI is partial light,but Z index is not characterized.However,the characteristic of drought indicated by SPEI is consistent with the data recorded.so it become the optimal drought index of the Jing-Jin-Ji region.(2)There are temporal difference about drought coverage area in different time scales.The drought has occurred in scale,spring and summer,among which the most severe drought in summer,in scale fall followed.Unobvious increasing trend appears in spring.In terms of decadal variation,the most severe drought happened in the 1990 s.Mutation test showed: Mutation points of years and spring in the middle of 1970 s,however,Mutation points of winter in 2012.drought coverage area of Jing-Jin-Ji region have 5a?6a?8a short cycle and 10 a?13a cycle.(3)In terms of spatial distribution,the drought coverage area in scale show that the slightest drought occured in the northwest,lighter in the northen,heavier in the middle of region,and the heaviest in the middle east of region.In addition to the sporadic lattice of northeast and west of region showed a trend of decline,others increased slightly.The drought coverage area in northwest is small in spring,but the increasing trend is verysignificant.The middle East of region not only have a large coverage,but also increase continuously;Although the drought coverage area of the remaining area is large,the trend tend to be alleviated later;The drought coverage area of summer is larger in the north of shijiazhuang and cangzhou,and the south is smaller.Except for a few points,the drought in the whole region will continue to increasing.(4)There are spatial difference about different levels of drought,the frequency of no drought show that the spatial distribution rule of a decreasing trend from north to south.The frequency of slight drought is more in the south of cangzhou-langfang changping-weixian,and the north is less.The frequency of moderate and above drought is stronger in the middle east of region,and the northwest and north is weaker.In the terms of changing trends,the frequency of no drought in the whole region have significantly decreasing trend,which indicates the drought tendency of the Jing-Jin-Ji region.The slight drought shows an decreasing trend in the southwest and zhangbei et al,and other regions are just the opposite.The changing trend of moderate and above drought is increasing in the northwest,other areas shows a decreasing trend.(5)Drought were caused by many factors in Jing-Jin-Ji region.among which,the more severe the sunspot activity was,the more strengthened the possible of drought,and the occurrence frequency and intensity of the drought near the maximum year were relatively large.El nino was more prone to drought and had a greater impact on the study area;Global warming not only increase the temperature,but also affects the nature climate variability ENSO,and ultimately affects the global climate system.(6).According to the typical drought year of year and summer in Jing-Jin-Ji region,the gray prediction model GM(1,1)that was established.and the precision of the model accuracy was found to be very good by residual error test and posteriori error test.The predicted results show that the next five possible drought years were 2020,2024,2029,2034 and 2039.The next five year in which the summer drought is likely to occur are 2027,2033,2040,2048 and 2056.