Analysis And Prediction Of Spatiotemporal Evolution Characteristics Of Extreme Climate In Jiangxi Province

Based on the daily precipitation and temperature data of 82 meteorological stations in Jiangxi Province from 1959 to 2013,combined with 27 international extreme climate indexes,the spatial distribution of extreme climate thresholds and the spatial and temporal evolution characteristics of extreme temperature and extreme precipitation events in Jiangxi Province in 55 years were analyzed by using linear fitting,trend change,moving average method and m-k mutation test.Using the regional climate model to predict the daily precipitation and temperature data in the future period(2030-2099),the temporal and spatial evolution characteristics of extreme climate events in Jiangxi Province are studied.The results show that:(1)On the whole,the spatial distribution of extreme low temperature threshold and extreme high temperature threshold in Jiangxi Province is quite different.The difference of low temperature threshold in north-south direction is larger than that in east-west direction.In terms of spatial distribution,the distribution patterns of extreme precipitation threshold and extreme heavy precipitation threshold are relatively consistent,both showing an increasing trend from southwest to northeast,and the extreme precipitation threshold is larger in some areas.(2)Research findings of extreme climate events in Jiangxi Province from 1959 to 2013,in terms of time change,the temperature cold index shows a downward trend,and the temperature warm index shows an upward trend.On the whole,the increase range of the warm index is larger than that of the cold index,and the extreme temperature index shows an upward trend.In the precipitation index,the number of continuous dry days and continuous wet days showed a downward trend,while other indicators showed a consistent upward trend.In terms of spatial distribution,the changes of temperature cold index(freezing days,frost days)and warm indexes(summer days and hot night days)showed opposite change characteristics,while the distribution of extreme temperature relative index in Jiangxi Province was relatively uniform,and the overall change range was not large.The regional characteristics of extreme precipitation in Jiangxi Province were more obvious,showing an increase from southwest to northeast The precipitation in Southwest China is relatively small,and the average daily precipitation intensity is small.The m-k mutation test analysis shows that 16 extreme temperature indexes in the study area have mutation,but the mutation time is different.The m-k statistical curve of 11 extreme precipitation indexes is relatively fluctuant,the mutation trend is not significant,and the mutation time is different.(3)The regional climate model regcm4.6 can simulate the temperature data better than the precipitation data.In terms of spatial distribution,the measured values of annual precipitation,daily maximum temperature and daily minimum temperature are consistent with the simulated values,and the maximum regions are also consistent.The simulation results for Lushan and Jinggangshan high altitude areas are also ideal.(4)In the future,under different emission scenarios,the temperature and precipitation will increase,that is,the maximum daily temperature will increase,and the daily maximum precipitation will also increase,and the increase range of RCP 8.5 will be the largest,followed by RCP 4.5,and RCP 2.6 will be the smallest.Under the three emission scenarios,the spatial distribution of the minimum daily temperature,maximum daily temperature,continuous dry days and daily maximum precipitation are consistent,and the maximum area is also consistent,and the change range is slightly different.