Mallet Marc, Nabat Pierre, Johnson Ben, Michou Martine, Haywood Jim M, Chen Cheng, Dubovik Oleg
CNRM, Université de Toulouse, Météo-France, CNRS, Toulouse, France.
Met Office, Exeter EX1 3PB, UK.
Sci Adv. 2021 Oct 8;7(41):eabg9998. doi: 10.1126/sciadv.abg9998.
The radiative budget, cloud properties, and precipitation over tropical Africa are influenced by solar absorption by biomass-burning aerosols (BBA) from Central Africa. Recent field campaigns, reinforced by new remote-sensing and aerosol climatology datasets, have highlighted the absorbing nature of the elevated BBA layers over the South-East Atlantic (SEA), indicating that the absorption could be stronger than previously thought. We show that most of the latest generation of general circulation models (GCMs) from the sixth phase of the Coupled Model Intercomparison Project 6 (CMIP6) underestimates the absorption of BBA over the SEA. This underlines why many (~75%) CMIP6 models do not fully capture the intense positive (warming) direct radiative forcing at the top of the atmosphere observed over this region. In addition, underestimating the magnitude of the BBA-induced solar heating could lead to misrepresentations of the low-level cloud responses and fast precipitation feedbacks that are induced by BBA in tropical regions.
热带非洲地区的辐射收支、云特性和降水受到来自中非的生物质燃烧气溶胶（BBA）对太阳辐射的吸收影响。近期的实地考察活动，借助新的遥感和气溶胶气候学数据集得到加强，凸显了东南大西洋（SEA）上空BBA层升高后的吸收特性，表明这种吸收可能比之前认为的更强。我们发现，耦合模式比较计划第6阶段（CMIP6）的最新一代通用循环模型（GCM）大多低估了SEA上空BBA的吸收。这凸显了为何许多（约75%）CMIP6模型无法充分捕捉该区域上空观测到的强烈正（变暖）大气顶层直接辐射强迫。此外，低估BBA引起的太阳加热幅度可能导致对热带地区BBA引发的低层云响应和快速降水反馈的错误表述。
