Simulation And Estimation Of Temperature In The Middle And Lower Reaches Of The Yangtze River Using Multi-model Based On Statistical Downscaling Method

At present,most global climate models(GCM)have low spatial resolution,and it is difficult to make reasonable predictions about climate change in regional scale.Now downscaling method has been widely used to make up for the deficiency of GCM in this aspect,This study conducted statistical downscaling of temperature in January and July of the middle and lower reaches of the Yangtze river region through a combination of stepwise linear regressions and principal component analysis approach,and predicted the future temperature change trend in this region.At first,the ECMWF's ERA-Interim data and measured data were used to establish a monthly statistical model,and then the established statistical downscaling model was applied to the Coupled Model Intercomparison Project Phase 5(CMIP5)multiple global climate models' data to generate the future temperature variation sequence of each station in the middle and lower reaches of the Yangtze river.The main research and conclusions are as follows:(1)a statistical downscaling model is established by using meteorological data of 105 stations in the downstream area of the ECMWF reanalysis data in the Yangtze River,the result can be seen that both two months are very good,although in two stations the correlation coefficient is less than 0.9 in July,but the correlation coefficient is above 0.89.(2)The data after downscaling can reproduce the spatial distribution characteristics of temperature increase for the ECMWF reanalysis data.(3)The model multi-model ensemble(MME)can effectively improve the simulation ability of the temperature in the study area.(4)MME model can further improve the model simulation ability when using the statistical downscaling multi-model ensemble(SDMME)model which is downscaled by MME.(5)Through the statistical downscaling prediction of three different emission scenarios in the future,we can see that at the end of the century,the temperature is higher than the current temperature 2~3 degrees at different emission scenarios,and the warming rate in July is larger than that in January.