Evaluation and projection of extreme climate indices over Hubei province by CMIP6 climate models

Based on the downscaled data of 14 global climate models from the Coupled Model Inter-comparison Project Phase 6 (CMIP6) and the meteorological observation dataset of CN05.1, we evaluated the simulation ability of CMIP6 models for 15 extreme climate indices over Hubei province, and projected the future trends under two Shared Socioeconomic Pathways scenarios (SSP2-4.5 and SSP5-8.5). The results are as follows. (1) All of the models can reasonably reproduce the spatiotemporal evolution of the extreme climate indices, and the simulation results of extreme temperature indices are better than those of extreme precipitation indices. In addition, the ensemble mean of multiple models is better than most of the models or represents the average simulation ability of the models. (2) Models may overestimate strong extreme warm indices, underestimate extreme cold indices and extreme precipitation indices, and the bias will increase with the extreme of the indices becoming greater. (3) The extreme warm indices in Hubei province will increase significantly in the future, and the growth rate in central and Eastern Hubei will be higher than that in other regions; Extreme cold indices decreased significantly, especially in Western and northeastern Hubei. (4) The frequency and intensity of heavy precipitation indices all show an increasing trend, especially in Eastern and southern Hubei, however, the drought indices show a trend of decreasing at first and then aggravating, and the extreme drought indices in Northwest Hubei in the late 21st century will be more obvious. (5) In most regions, the growth rate of extreme warm indices, extreme precipitation indices and drought indices will reach the maximum in the late 21st century. Under the SSP5-8.5 scenario, the area of high-value will be larger and the increase will become greater than those under the SSP2-4.5 scenario.