Surprising similarities in model and observational aerosol radiative forcing estimates.
Surprising similarities in model and observational aerosol radiative forcing estimates.
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DOI：
10.5194/acp-20-613-2020
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发表时间：
2020-01
影响因子：
6.3
通讯作者：
Zhang K
中科院分区：
文献类型：
--
作者：
Gryspeerdt E;Mülmenstädt J;Gettelman A;Malavelle FF;Morrison H;Neubauer D;Partridge DG;Stier P;Takemura T;Wang H;Wang M;Zhang K
气溶胶的辐射强迫（特别是通过它们与云的相互作用）仍然是人类对气候强迫中最不确定的组成部分之一。基于观测的研究通常发现气溶胶的有效辐射强迫小于模式模拟，在政府间气候变化专门委员会（IPCC）第五次评估报告（AR5）中给予优先权重。由于它们自身的不确定性来源，尚不清楚基于观测的估计是否更可靠。因此，了解模式和观测差异的来源对于减少气溶胶对气候影响的不确定性至关重要。这些报告的差异是由于模式研究和观测研究中使用的分离气溶胶强迫成分的不同方法造成的。将观测分解应用于全球气候模式（GCM）的输出，这两种不同的证据惊人地相似，在气溶胶对云特性的影响程度上有更好的一致性。云的调整仍然是一个重要的不确定性来源，尤其是冰云。然而，它们与基于观测方法的不确定性一致，液态水路径调整通常使Twomey效应增强不到50%。根据不同的假设集，这项工作表明，在未来的综合研究中，模型和基于观测的估计可以更加平等地加权。
The radiative forcing from aerosols (particularly through their interaction with clouds) remains one of the most uncertain components of the human forcing of the climate. Observation-based studies have typically found a smaller aerosol effective radiative forcing than in model simulations and were given preferential weighting in the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5). With their own sources of uncertainty, it is not clear that observation-based estimates are more reliable. Understanding the source of the model and observational differences is thus vital to reduce uncertainty in the impact of aerosols on the climate. These reported discrepancies arise from the different methods of separating the components of aerosol forcing used in model and observational studies. Applying the observational decomposition to global climate model (GCM) output, the two different lines of evidence are surprisingly similar, with a much better agreement on the magnitude of aerosol impacts on cloud properties. Cloud adjustments remain a significant source of uncertainty, particularly for ice clouds. However, they are consistent with the uncertainty from observation-based methods, with the liquid water path adjustment usually enhancing the Twomey effect by less than 50%. Depending on different sets of assumptions, this work suggests that model and observation-based estimates could be more equally weighted in future synthesis studies.