Bias correction and projection of surface air temperature in LMDZ multiple simulation over central and eastern China

摘要

Based on LMDZ4 daily temperature dataset,equidistant cumulative distribution function matching method (EDCDFm) and cumulative distribution function-transform method (CDF-t) are used to evaluate the ability of models in simulating extreme temperature over central and eastern China.The future temperature change is then projected.The results show that the EDCDFm and CDF-t methods function effectively correct the spatial distribution of daily mean temperature and extreme temperature,significantly reduce the biases of the model simulation and effectively improve the capacity of models for spatial pattern of extreme temperature.However,the cold bias of the CDF-t method in winter is obviously higher than that of the EDCDFm method,and the temperature change curve of the EDCDFm method is closer to the observation than that of the CDF-t method.The projection based on the EDCDFm method shows that under the RCP4.5 emission scenario,the temperature in the study area shows a warming trend.Relative to 1986-2005,the mean temperature is projected to increase by 0.76,1.84,and 2.10 ℃ during 2017-2036,2046-2065,and 2080-2099,respectively.The spatial change for the mean,maximum,and minimum temperature in the three future periods have good consistency;warming in northern China is higher than that in the south.Uncertainties in temperature projection are large in the Tibetan Plateau and Sichuan Basin.Frost days decrease significantly,especially in the Tibetan Plateau,and the frost days in the three periods decrease by more than 15,30,and 40 d,respectively.The variation of heat wave indice is the smallest;the increase of heat wave is mainly in eastern China,and the increase in South China is more than 2 d.Besides,under the global warming of 1.5 ℃ and 2 ℃,the response characteristics of extreme temperature over central and eastern China are also analyzed.The results show that the mean temperature,maximum temperature and minimum temperature in the study area increase by more than 0.75 ℃ under 1.5 ℃ target and over 1.25 ℃ under 2 ℃ target,especially in the northwestern China and the Tibetan Plateau,relative to 1986-2005.Additionally,comparing two warming targets,the difference of three temperature indices in parts of northeastern China is over 1.5 ℃,while more than 3 d for heat wave.