Opportunistic experiments to constrain aerosol effective radiative forcing.
Opportunistic experiments to constrain aerosol effective radiative forcing.
复制标题
DOI：
10.5194/acp-22-641-2022
复制
发表时间：
2022-01
影响因子：
6.3
通讯作者：
Yuan T
中科院分区：
文献类型：
--
作者：
Christensen MW;Gettelman A;Cermak J;Dagan G;Diamond M;Douglas A;Feingold G;Glassmeier F;Goren T;Grosvenor DP;Gryspeerdt E;Kahn R;Li Z;Ma PL;Malavelle F;McCoy IL;McCoy DT;McFarquhar G;Mülmenstädt J;Pal S;Possner A;Povey A;Quaas J;Rosenfeld D;Schmidt A;Schrödner R;Sorooshian A;Stier P;Toll V;Watson-Parris D;Wood R;Yang M;Yuan T
气溶胶-云相互作用（ACI）被认为是人类活动造成的当今辐射强迫最不确定的驱动因素。云状态变化对气溶胶扰动的非线性使得在观测到的气溶胶辐射强迫关系中归因因果关系具有挑战性。当气象变化也独立驱动气溶胶和云的变化时，使用相关性来推断因果关系可能具有挑战性。来自明确来源的自然和人为气溶胶扰动提供了“机会性实验”（也称为自然实验），以在因果关系可能更有把握地推断的情况下调查ACI。这些扰动涵盖了广泛的位置和时空尺度，包括火山爆发或工业源等点源，生物质燃烧或森林火灾产生的羽流，以及个别船只或航运走廊的轨迹。我们回顾了不同的实验条件，并对现有的卫星数据集和实地活动进行了综合，以将这些机会主义实验置于一个共同的基础上，促进对气溶胶辐射强迫中关键不确定性的新见解和更清晰的理解。云扰动对背景气象条件非常敏感。强液态水路径增加气溶胶扰动在很大程度上排除了平均跨实验。物理实验显著提高了对ACI过程水平的理解，但仍不清楚所发现的关系如何可靠地扩展到全球水平，因此表明需要进行更深入的研究，以改善对气溶胶辐射强迫和气候变化的评估。
Aerosol–cloud interactions (ACIs) are considered to be the most uncertain driver of present-day radiative forcing due to human activities. The nonlinearity of cloud-state changes to aerosol perturbations make it challenging to attribute causality in observed relationships of aerosol radiative forcing. Using correlations to infer causality can be challenging when meteorological variability also drives both aerosol and cloud changes independently. Natural and anthropogenic aerosol perturbations from well-defined sources provide “opportunistic experiments” (also known as natural experiments) to investigate ACI in cases where causality may be more confidently inferred. These perturbations cover a wide range of locations and spatiotemporal scales, including point sources such as volcanic eruptions or industrial sources, plumes from biomass burning or forest fires, and tracks from individual ships or shipping corridors. We review the different experimental conditions and conduct a synthesis of the available satellite datasets and field campaigns to place these opportunistic experiments on a common footing, facilitating new insights and a clearer understanding of key uncertainties in aerosol radiative forcing. Cloud albedo perturbations are strongly sensitive to background meteorological conditions. Strong liquid water path increases due to aerosol perturbations are largely ruled out by averaging across experiments. Opportunistic experiments have significantly improved process-level understanding of ACI, but it remains unclear how reliably the relationships found can be scaled to the global level, thus demonstrating a need for deeper investigation in order to improve assessments of aerosol radiative forcing and climate change.