Understanding and constraining the parametric uncertainty of climate sensitivity

气候敏感性（CS）是指全球平均地表气温对大气CO2浓度加倍的响应，具有很大的不确定性。在这项研究中，我们构造了一个扰动物理系综（PPE）的MIROC5气候模式来研究CS的参数不确定性。短波云反馈（SWcld）主导CS的变化。为了研究CS的参数和结构不确定性，我们还提出了多参数多物理系综（MMPPE）。我们使用了八个多物理系综（MPE）模型，其中MIROC5物理方案被MIROC3物理方案所取代。MMPPE由每个MPE型号的PPE组成。低层和中层云之间的耦合控制了MPE模型之间SWcld参数分布的差异。

Climate sensitivity (CS), which is defined as the global mean surface air temperature response to a doubling of the atmospheric CO2 concentration, has large uncertainties. In this study, we constructed a perturbed physics ensemble (PPE) for the MIROC5 climate model to investigate the parametric uncertainty of CS. The shortwave cloud feedback (SWcld) dominated the variations in CS. To explore both the parametric and structural uncertainties of CS, we also proposed the multi-parameter multi-physics ensemble (MPMPE). We used eight multi-physics ensemble (MPE) models in which the MIROC5 physics schemes were replaced by those of MIROC3. MPMPE consisted of PPE for each MPE model. Coupling between low- and mid-level clouds controlled the differences in the parametric spread of SWcld among the MPE models.