AUTHOR=Li Xiehui , Chen Zifan , Wang Lei , Liu Huan TITLE=Future projections of extreme temperature events in Southwest China using nine models in CMIP6 JOURNAL=Frontiers in Earth Science VOLUME=10 YEAR=2022 URL=https://www.frontiersin.org/journals/earth-science/articles/10.3389/feart.2022.942781 DOI=10.3389/feart.2022.942781 ISSN=2296-6463 ABSTRACT=

Southwest China, which is close to the Qinghai-Tibet Plateau, presents complex topography. As a result of the combined influence of the South Asian monsoon, East Asian monsoon, and plateau monsoon, climate in this region is unique. Since Southwest China is one of the areas where extreme weather events occur more frequently, this region is sensitive and vulnerable to climate change. In the present research, daily temperature from 1969 to 2020 recorded at 93 weather stations in Southwest China, and data from nine models for the period 1995 to 2040 were used in CMIP6 (Coupled Model Intercomparison Project Phase 6) to calculate 17 ETIs (Extreme Temperature Indices). Furthermore, we analyzed and compared the annual change rate, temporal and spatial change trend, and mean change of extreme temperature events in Southwest China and four subzones during historical period and under SSP2-4.5 scenario for the next 20 years. The results showed: 1) The 8 ECTIs (Extreme Cold Temperature Indices) and the 8 EWTIs (Extreme Warm Temperature Indices) in 1969–2020 were corroborated. These results indicated a warming trend. Also, DTR (Diurnal temperature range) showed a decreasing trend, and different degrees of warming were observed in the four subzones. 2) From 2021 to 2040 and under the SSP2-4.5 scenario, the annual rates of change for 17 ETIs in Southwest China showed that extreme cold events will continue to decrease. On the other hand, extreme warm events will continue to increase. 3) Under the SSP2-4.5 scenario in the next 20 years, CSDI (cold spell duration indicator) will decrease, while WSDI (warm spell duration indicator), TMINmean (average daily minimum temperature), and TMAXmean (average daily maximum temperature) will increase. Moreover, the decrease in amplitude of CSDI was smaller than the increase in amplitude of WSDI. Also, the increase in amplitude of TMINmean was slightly smaller than that of TMAXmean. The projected WSDI, TMINmean, and TMAXmean obtained with the preferred three models and MEM-9 (nine-Model Ensemble Mean) showed an overall growing trend with respect to space; however, the increased range fluctuated in different regions. 4) In 2021–2040, mean values of 4 ETIs in different subzones indicated that the lowest TMINmean and TMAXmean were observed in the ZP (Zoigê Plateau), the highest in the YGP (Yunnan-Guizhou Plateau), and intermediate higher in the SB (Sichuan Basin). Compared with the 4 ETI mean values corresponding to 1969–2020, the persistence and average state of extreme cold and warm events in different subzones showed that future change trends depend on altitude.