The Oceanic Fingerprint of the Forced Response to Anthropogenic Aerosols

人类对大气的排放以两种方式影响我们的气候：通过增加温室气体，改变我们的星球通过辐射回到太空的冷却效率；通过气溶胶对大气亮度和云量的影响，改变到达地球表面的阳光数量。人们对全球温室气体的变暖效应的了解比对人为气溶胶的降温效应的了解更多，人为气溶胶的作用更多地是区域性的(靠近北半球的排放点)。量化这两个对立的气候驱动因素在多大程度上对过去的变化负有责任也是具有挑战性的，因为我们的气候系统也存在自然的混乱波动。海洋是控制地球气候变化速度和形式的主要参与者。这个项目将利用来自Argo阵列的史无前例的全球海洋观测和一大套气候模型运行(这些模型捕捉到了地球上的许多气候混乱)，试图梳理出我们最近过去气候上的气溶胶和温室气体的指纹。该团队将解决的一些问题是：气溶胶效应在过去是结束了还是被低估了？海洋受到了怎样的影响？最终，该小组的目标是帮助改进气候预测，从而支持社区采取更好的缓解和适应行动。该项目还将支持和帮助培养博士后科学家。在过去的几十年里，人类成因的气溶胶以及温室气体(GHG)造成了巨大的气候变化，而对前者的了解和量化要少得多。虽然以前的大多数研究侧重于地表或大气响应，但调查人员将调查人为气溶胶强迫导致的海洋水团和环流如何演变，与历史时期和未来预测中的内部变率和温室气体强迫变化的背景形成对比。为了将外部强迫信号从内部气候变化中分离出来，他们将利用具有共同外部强迫但不同初始条件的单一大气环流模式来开发新的大型集合模拟。他们将侧重于比较外力分量和内部变异性，评估各种时空分析方法在分离这些信号方面的性能及其估计的稳健性。该团队希望开发出在模型运行中发现的海洋内部对人为气溶胶强迫的反应指纹，然后检查在观测、非强迫控制运行、其他人为强迫运行以及自然外部强迫运行中检测到这些指纹的可能性。他们将尝试从观测中识别并消除内部变异性，以测试是否可以提高强迫信号指纹的可检测性。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Human emissions to the atmosphere impact our climate in two ways: changing how efficiently our planet cools via radiation back to space through increasing greenhouse gases; and changing how much sunlight reaches Earth’s surface via the impacts of aerosols on atmospheric brightness and cloudiness. More is understood about the warming effect of greenhouse gases, which act globally, than the cooling effect of anthropogenic aerosols, which act more regionally (close to emission sites in the northern hemisphere). Quantifying how much these two opposing climate drivers are responsible for past change is also challenging, as our climate system also has natural chaotic fluctuations. The ocean is a major player in controlling the rate and form of change in Earth’s climate. This project will exploit the unprecedented global ocean observations from the Argo array and a large set of climate model runs (which capture a lot of Earth’s climate chaos) to try to tease apart the fingerprint of aerosols versus greenhouse gases on our recent past climate. Some of the questions the team will address are: Has the aerosol effect been over or underestimated in the past? How has the ocean been impacted? Ultimately the team aims to help improve climate projections and thus support better mitigation and adaptation actions by the community. The project will also support and help train a postdoctoral scientist.Anthropogenic aerosols, along with greenhouse gases (GHG), have caused substantial climate change over the past several decades, with the former much less understood and quantified. While most previous studies have focused on surface or atmospheric responses, the investigators will investigate how the ocean water masses and circulation evolve due to anthropogenic aerosol forcing in contrast to the background of internal variability and GHG-forced changes during the historical period and in future projections. To isolate externally forced signal from internal climate variability, they will exploit new large ensemble simulations using a single general circulation model with common external forcing but different initial conditions. They will focus on comparing the externally forced component and internal variability, evaluation of the performance of various spatiotemporal analysis methods in separating those signals and the robustness of their estimation. The team hopes to develop fingerprints of the ocean interior response to anthropogenic aerosol forcing found in the model runs, and then examine how likely it is to detect these fingerprints in the observations, unforced control runs, runs with other anthropogenic forcing, and runs with natural external forcing. They will attempt to identify and remove the internal variability from the observations to test whether the detectability of the fingerprint of the forced signal can be improved.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.