Simulation and Prediction of Extreme Temperature Indices in Yangtze and Yellow River Basins by CMIP5 Models

To study the change characteristics of extreme temperature in the Yangtze and Yellow River basins,the output data from 22 general climate models (GCMs) of the coupled model intercomparison project phase 5 (CMIP5) were selected.The data were processed by accuracy evaluation and delta downscaling,then 16 extreme temperature indices were calculated based on these data. The ensemble reliability average (REA) results were selected for historical simulation and future prediction of extreme temperature over the two basins. The results show that the spatial characteristics of the observations are in good agreement with that of the REA values,except for the Sichuan basin. During the three periods(2020s,2050s,2080s) in future,the trends of the indices would continually decrease under the Representative Concentration Pathways (RCP) 4.5 scenario,while the trends of these indices would increase under the RCP8.5 scenario. The variation of the indices is similar before the 1940s under the RCP4.5 and RCP8.5 scenarios,however,the variation characteristics under RCP4.5 and RCP8.5 have a significant difference since the 1940s. In the future,most indices would show upward trends,especially in winter. Moreover,the difference of the cold extreme indices between the two basins are greater than the difference of the warm extreme indices.In general,warm extreme events in the Yangtze and Yellow River basins will be more serious in future.