Department of Earth and Environmental Sciences, Columbia University, New York, NY, USA.
International Research Institute for Climate and Society, The Earth Institute at Columbia University, New York, NY, USA.
Sci Rep. 2020 Jul 22;10(1):12203. doi: 10.1038/s41598-020-68356-w.
There is little scientific consensus on the importance of external climate forcings-including anthropogenic aerosols, volcanic aerosols, and greenhouse gases (GHG)-relative to each other and to internal variability in dictating past and future Sahel rainfall. We address this query by relating a 3-tiered multi-model mean (MMM) over the Climate Model Intercomparison Project phase 5 "twentieth century" and pre-Industrial control simulations to observations. The comparison of single-forcing and historical simulations highlights the importance of anthropogenic and volcanic aerosols over GHG in generating forced Sahel rainfall variability in models. However, the forced MMM only accounts for a small fraction of observed variance. A residual consistency test shows that simulated internal variability cannot explain the residual observed multidecadal variability, and points to model deficiency in simulating multidecadal variability in the forced response, internal variability, or both.
关于外部气候强迫因素（包括人为气溶胶、火山气溶胶和温室气体）相对于彼此以及内部变率在决定过去和未来萨赫勒降雨方面的重要性，科学界尚未达成共识。我们通过将气候模型比较计划第 5 阶段“20 世纪”和工业化前控制模拟的三层多模型平均值（MMM）与观测结果相关联来解决这一问题。单强迫和历史模拟的比较强调了人为和火山气溶胶相对于温室气体在模型中产生强迫萨赫勒降雨变化方面的重要性。然而，强迫 MMM 仅占观测方差的一小部分。剩余一致性检验表明，模拟的内部变率不能解释观测到的多十年剩余可变性，这表明模型在模拟强迫响应、内部变率或两者的多十年变率方面存在缺陷。
