NSF-BSF: Quantitative Evaluation of Aerosol Impacts on the Microphysical Composition, Electrification and Radiative Forcing of Deep Tropical Convective Clouds

NSF-BSF：气溶胶对热带深层对流云微物理成分、带电和辐射强迫影响的定量评估

• 批准号: 2113494
• 负责人: Joel Thornton
• 金额: $ 48.94万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2024-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2113494&HistoricalAwards=false
• 关键词: NSF; BSF; Quantitative; Evaluation; Aerosol

Atmospheric aerosol particles range in size from a few nanometers to tens of micrometers and have both natural and anthropogenic sources. Aerosol particles act as cloud condensation nuclei (CCN), and therefore changes in aerosol particle abundance can alter the cloud drop concentrations and subsequently cloud reflectivity and lifetime as well as associated precipitation. Tropical deep convective clouds (DCC) are important to Earth’s global energy balance and hydrologic cycle and can induce high impact weather with significant precipitation and lightning. However, the effects of aerosol particles on DCC properties, including the onset and amount of precipitation, vertical development, electrification and associated lightning, and the extent and lifetime of associated high altitude ice clouds, remain poorly quantified. In this project, the effect of aerosol particles on such weather and climate related phenomena is studied, addressing a major open question of whether and how human-induced aerosol particle pollution has altered weather phenomena (e.g., potentially moving tropical showers to thunderstorms), and climate. Global climate models are being used to inform socioeconomic policy decisions around the world, but the processes investigated in this project are practically absent from these models. Therefore, the outcome of this study could have broad impacts on our understanding of the anthropogenic aerosol impacts on climate predictions and in turn upon policies being developed for mitigation and adaptation. The project will train graduate and undergraduate students through international collaboration in the fundamental physics and chemistry of the atmosphere and developing their technical skills in the analysis of large multivariable datasets, 3-dimensional computer models of the atmosphere, and satellite remote sensing technology. Tropical marine regions are likely most sensitive to the additional input of aerosol particles which act CCN. Ultrafine aerosol particles (UAP) 40 nm in size are not typically considered CCN, but they may in fact nucleate cloud droplets in DCC. Observations of UAP, specifically, and CCN, are lacking in such clean regions needed to test hypotheses about the aerosol impacts on deep convective clouds and associated effects on climate. To address these limitations, this joint NSF-BSF project between University of Washington (UW), The Hebrew University Jerusalem Israel (HUJI), and collaborators, leverages i) remote sensing of DCC microphysics to constrain CCN and UAP impacting individual convective events, ii) analysis of 15 years of global tropical lightning stroke fields guided by chemical transport model predictions of UAP and CCN, and iii) cloud resolving modelling of key domains constrained by the satellite remote sensing insights, lightning observations, and chemical transport model predictions of UAP and CCN. The project will evaluate how CCN, including UAP, perturb the microphysics of tropical deep convective clouds and to what extent such perturbations affect lightning and cloud radiative effects, and provide a test of the hypothesis that increases in CCN and UAP since preindustrial time, due to human activities associated with fuel combustion, have induced a positive radiative forcing (warming) on climate through deep convective clouds. Such a climate forcing would be in opposition to the negative radiative forcing in which CCN increases affects low cloud albedo and lifetime and would alter our understanding of climate sensitivity.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.

大气气溶胶颗粒的大小从几纳米到数十微米，具有天然和人为来源。气溶胶颗粒充当云凝结核（CCN），因此气溶胶颗粒丰度的变化会改变云滴浓度，随后云反射率和寿命以及相关的降水。热带深度对流云（DCC）对地球的全球能量平衡和水文循环很重要，并且可以通过大量降水和闪电诱导高影响天气。但是，气溶胶颗粒对DCC特性的影响，包括降水的发作和量，垂直发育，电气和相关的闪电以及相关的高空冰云的程度和寿命，仍然量化不佳。在该项目中，气溶胶颗粒对这种天气和气候相关现象的影响是研究的，它解决了一个主要的开放问题，即人类引起的气溶胶颗粒污染是否改变了天气现象（例如，潜在地移动的热带淋浴到雷暴）和气候。全球气候模型被用来为世界各地的社会经济政策决策提供信息，但是这些模型实际上没有该项目所研究的过程。因此，这项研究的结果可能会对我们对人为气溶胶对气候预测的影响以及对缓解和适应制定的政策产生的影响产生广泛的影响。该项目将通过在大气的基本物理和化学方面的国际合作来培训毕业生和本科生，并在分析大型多变量数据集，大气的三维计算机模型以及卫星远程灵敏度技术方面发展其技术技能。热带海洋区域可能对ACT CCN的气溶胶颗粒的额外输入最敏感。 Ultrafine气溶胶颗粒（UAP）40 nm通常不被视为CCN，但实际上它们可能在DCC中的核云液滴。在此类清洁区域中，缺乏对UAP的观察结果，并且缺乏测试有关气溶胶对深对流云的影响以及对气候的相关影响的假设所需的清洁区域。 To address these limitations, this joint NSF-BSF project between University of Washington (UW), The Hebrew University Jerusalem Israel (HUJI), and collaborators, leverages i) remote sensitivity of DCC microphysics to constrain CCN and UAP impacting individual convective events, ii) analysis of 15 years of global tropical lightning stroke fields guided by chemical transport model predictions of UAP and CCN, and iii)通过卫星遥感见解，闪电观测和UAP和CCN的化学传输模型预测，云解析关键域的建模。该项目将评估CCN（包括UAP）如何扰动热带深度对流云的微观物理学以及这种扰动在多大程度上影响闪电和云辐射效应，并对CCN和UAP的假设进行测试，该假说自因工业化时间而增加，这是由于与燃料混合物相关的工业化时间而引起的，这会引起良好的辐射（升温），因此构成了强化的强化（泛滥）。反对CCN增加的负面辐射强迫会影响低云反映和终生，并将改变我们对气候敏感性的理解。该奖项反映了NSF的法定任务，并被认为是通过基金会的智力优点评估而被视为珍贵的支持，并具有更广泛的影响。