Quantifying aerosol-cloud-climate effects by regime

The goal of QUAERERE (Latin for researching) is a reliable, observations-based, global quantification of aerosol indirect effects, which would also imply a constraint on climate sensitivity and thus climate predictions. This goal is now reachable combining recent advances in different disciplines: (i) a decade-long satellite dataset involving retrievals of the relevant quantities is now available, complemented by a complete aerosol dataset from a new reanalysis; (ii) on the basis of high-resolved numerical weather prediction models, which include parameterisations of aerosol cycles and cloud-precipitation microphysics, cloud-system resolving simulations at a regional scale are now possible; reliable simulations beyond idealised cases are thus possible. These tools are complemented by comprehensive global climate models and reference ob­ servations from ground-based sites. The problem in aerosol-cloud-climate effects is in its complexity: Various processes counteract each other, and large spatiotemporal variability of clouds buffers the forcing effects. QUAERERE proposes a two-fold divide-and-conquer approach to this complex problem: (i) aerosol-cloud-climate effects will be investigated by regime; this allows to circumvent the problem of aerosol-cloud-climate effects being buffered when averaging over different regimes; and (ii) by investigating individual terms contributing to the aerosol-cloud-climate effects separately; this allows to analyse individual statistical relationship in satellite observations and model results consistently, and to perform model sensitivity studies for cause-effect attribution. QUAERERE is funded by European Research Council (Call ERC-2012-StG, PE10, FP7 ideas starting grant 306284).

QUAERERE（拉丁语意为研究）的目标是实现基于观测的、可靠的全球气溶胶间接效应的量化，这亦意味着对气候敏感性及其预测的约束。该目标如今得以实现，得益于不同学科领域的近期进展：（一）一个长达十年的卫星数据集，包括相关量的检索，现已成为可用资源，并辅以新的再分析提供的完整气溶胶数据集；（二）基于高分辨率数值天气预报模型，其中包含气溶胶循环和云降水微物理过程的参数化，区域尺度的云系解析模拟成为可能；因此，能够在超越理想化案例的情况下进行可靠的模拟。这些工具得到了全面的全球气候模型和地面观测站点的参考观测的补充。气溶胶-云-气候效应的问题在于其复杂性：各种过程相互制衡，而云的大时空变异性缓冲了强迫效应。QUAERERE针对这一复杂问题提出了分而治之的两步策略：（一）将气溶胶-云-气候效应按气候类型进行研究，这使得绕过在平均不同气候类型时气溶胶-云-气候效应被缓冲的问题成为可能；（二）分别研究对气溶胶-云-气候效应有贡献的各个项；这允许在卫星观测和模型结果中一致地分析单个统计关系，并执行针对因果归因的模型敏感性研究。QUAERERE由欧洲研究委员会（ERC-2012-StG，PE10，FP7 ideas启动资助306284）资助。