Uncertainty of ENSO-amplitude projections in CMIP5 and CMIP6 models
Uncertainty of ENSO-amplitude projections in CMIP5 and CMIP6 models
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DOI：
10.1007/s00382-021-05673-4
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发表时间：
2021-02-11
期刊：
影响因子：
4.6
通讯作者：
Latif, Mojib
中科院分区：
文献类型：
--
作者：
Beobide-Arsuaga, Goratz;Bayr, Tobias;Latif, Mojib
关于厄尔尼诺/南方涛动（ENSO）振幅如何在21世纪响应全球变暖而变化，存在长期争论。本文确定了参与耦合模式比较第5阶段（CMIP5）和第6阶段（CMIP6）的模式中ENSO幅度预估的不确定性来源，并量化了情景不确定性、模式不确定性和内部变率不确定性。模式预估显示出很大的差异，到21世纪末，从标准偏差增加到0.6摄氏度，到标准偏差减少到- 0.4摄氏度。整体平均ENSO振幅变化接近于零。内部变率是前三十年不确定性的主要因素；此后模式不确定性占主导地位，而情景不确定性在整个21世纪相对较小。从CMIP5到CMIP6，总不确定性增加：模式不确定性降低，情景不确定性显著增加。对具有“真实”ENSO动力学的模式进行了单独分析，并将其分为与仪器观测值相比幅度过小、中等和过大的模式。最小的不确定度在子集合中观测到，表现出真实的ENSO动力学和中等的ENSO振幅。然而，enso振幅变化中的全球变暖信号在所有子系统中都无法检测到。纬向风-海温反馈是决定ENSO振幅变化的重要因素，全球变暖信号在ENSO振幅与纬向风-海温反馈强度在CMIP5和CMIP6模式中高度相关。
There is a long-standing debate on how the El Nino/Southern Oscillation (ENSO) amplitude may change during the twenty-first century in response to global warming. Here we identify the sources of uncertainty in the ENSO amplitude projections in models participating in the Coupled Model Intercomparison Phase 5 (CMIP5) and Phase 6 (CMIP6), and quantify scenario uncertainty, model uncertainty and uncertainty due to internal variability. The model projections exhibit a large spread, ranging from increasing standard deviation of up to 0.6 degrees C to diminishing standard deviation of up to - 0.4 degrees C by the end of the twenty-first century. The ensemble-mean ENSO amplitude change is close to zero. Internal variability is the main contributor to the uncertainty during the first three decades; model uncertainty dominates thereafter, while scenario uncertainty is relatively small throughout the twenty-first century. The total uncertainty increases from CMIP5 to CMIP6: while model uncertainty is reduced, scenario uncertainty is considerably increased. The models with "realistic" ENSO dynamics have been analyzed separately and categorized into models with too small, moderate and too large ENSO amplitude in comparison to instrumental observations. The smallest uncertainties are observed in the sub-ensemble exhibiting realistic ENSO dynamics and moderate ENSO amplitude. However, the global warming signal in ENSO-amplitude change is undetectable in all sub-ensembles. The zonal wind-SST feedback is identified as an important factor determining ENSO amplitude change: global warming signal in ENSO amplitude and zonal wind-SST feedback strength are highly correlated across the CMIP5 and CMIP6 models.