CMIP6模式对亚洲中高纬区极端温度变化的模拟及预估

Assessment and projection of changes in temperature extremes over the mid-high latitudes of Asia based on CMIP6 models

摘要:

利用观测的亚洲中高纬区逐日最高、最低气温和CMIP6计划中28个全球气候模式资料，系统评估了CMIP6模式对亚洲中高纬区日最高温（TXx）和日最低温（TNn）的模拟性能，并对其未来演变趋势进行了科学预估。主要结论如下：1）CMIP6大部分模式能合理地模拟亚洲中高纬区TXx和TNn自南向北、自西到东逐渐降低的空间分布特征，但所有模式均在青藏高原北部地区附近存在较大的冷偏差。模式对气候平均态的模拟一致性较好，对TNn的模拟优于TXx；但是对于趋势变化模拟，对TXx的模拟与观测更为接近，而且多模式集合的模拟效果更优。2）预估结果指出，日最高气温和最低气温在21世纪均表现出显著增温趋势，其中TNn增加趋势更加明显。在SSP5-8.5排放情景下，到了21世纪末期，TXx约增加7.0 ℃，TNn约增加9.6 ℃。此外，预估结果不确定性随时间推移、排放增多而增加，其中对于TXx的预估结果可信度更高。

Abstract:

In this study, the performance of Coupled Model Intercomparison Project Phase 6 (CMIP6) models in simulating the temperature extremes, including the annual maximum of daily maximum temperature (TXx) and annual minimum of daily minimum temperature (TNn) over the mid-high latitudes of Asia are comprehensively assessed, as are their future changes.The main findings are as follows:1) The observed spatial distributions of extreme temperatures that decreases from south to north and west to east over the mid-high latitude of Asia are reasonably reproduced by most CMIP6 models, but the cold bias is still obvious over the Tibetan Plateau.Additionally, the higher skill is generally observed for the climate mean simulation of TNn rather than TXx, while a relatively higher skill is for the TXx of the trend simulation.The multimodel ensemble mean (MME) generally outperforms the individual models.2) The results of future projection indicate that both TXx and TNn show a significant increasing trend in the 21st century, but the increase in magnitude of TNn is shown to be much greater than that of TXx.Under the SSP5-8.5 scenario, both TXx and TNn are projected to increase by approximately 7.0℃ and 9.6℃ by the end of the 21st century, with respect to the current state (1995-2014).The projection uncertainty is estimated to increase with time and scenarios, and the increase of TXx shows a higher model agreement.