Increased interannual variability of temperature over China during the last interglacial and last glacial maximum: Magnitudes and asymmetric seasonal patterns

Based on multimodel simulations from phase 6 of the Coupled Model Intercomparison Project (CMIP6), this study analyzes the interannual variability of near-surface air temperature over China during the past warm period of the Last Interglacial (LIG) and the cold period of the Last Glacial Maximum (LGM), along with associated driving mechanisms. Results show that the interannual temperature variability increases for both periods, with an average of 8% during the LIG and 15% during the LGM relative to the preindustrial period over China. For the LIG, temperature variability increases more in summer than in winter, driven mainly by sensible heat flux, surface upward longwave radiation, and top-of-atmosphere outgoing shortwave radiation due to orbital forcing. In contrast, the LGM exhibits stronger winter but weaker summer variability, largely governed by top-of-atmosphere outgoing shortwave and longwave radiation together with surface downward shortwave and upward longwave radiation, because of global cooling induced by lower greenhouse gas concentrations. In both periods, the annual mean temperature variability enhances notably over eastern China, though with asymmetric seasonal differences similar with the patterns at the national scale. 基于CMIP6多模式试验数据, 本文研究了过去偏暖的末次间冰期 (LIG) 和偏冷的末次冰盛期 (LGM) 中国近地表气温年际变率的变化及机制.相对于工业革命前, 两时期中国温度变率均增大, LIG和LGM平均增幅分别为8%和15%.季节上, LIG夏季温度变率增幅大于冬季, 这主要由轨道强迫下感热通量,地表向上长波辐射和大气层顶向外短波辐射变化所主导;LGM冬季变率增幅总体强于夏季, 且与温室气体浓度降低导致的全球降温有关, 主要受大气层顶向外短波和长波辐射,地表向下短波和向上长波辐射共同控制.两时期中国东部年均温度变率均显著增强, 其季节不对称性与全国平均类似.