Collaborative Research: Examining Cloud-Radiation Feedback at Convective Scales in Tropical Cyclones

合作研究：检查热带气旋对流尺度的云辐射反馈

• 批准号: 2331120
• 负责人: James Ruppert
• 金额: $ 43.86万
• 依托单位: University of Oklahoma Norman Campus
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-11-01 至 2026-10-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2331120&HistoricalAwards=false
• 关键词: Collaborative; Research; Examining; Cloud; Radiation

The overarching goal of this research is to expand our understanding of how tropical cyclones (e.g., hurricanes and typhoons) form and intensify. Tropical cyclones are the leading driver of losses to life and property in the US, with coastal population growth and climate change exacerbating these impacts. However, many gaps remain in understanding their formation and intensification, despite decades of study. This project therefore addresses an issue that only grows more pressing with time. The investigators will examine the interaction between clouds and radiation. Recent work reveals that this interaction accelerates the formation of tropical cyclones. This project will advance our understanding of this feedback at the scales of individual thunderstorm systems. By doing so, this research will ultimately help improve the forecasting of tropical cyclones, which will in turn help mitigate losses of life and property when they make landfall. The project will also directly support the leadership and professional development of early-career scientists, graduate researchers, and undergraduate researchers. In support of advancing STEM education, the project team will conduct K-12 educational outreach through “Skype a Scientist” and other virtual activities.To address science gaps related to cloud–radiation feedback in tropical cyclones (TCs), this research will address the following questions:1. What are the responses of buoyancy, vertical motion, and moist entropy to cloud–radiation forcing (CRF) on convective scales in tropical shallow convection, deep convection, and stratiform rainfall?2. What are the unique roles of radiative feedback in these regimes in accelerating convective upscale development and TC genesis, and through what mechanism(s) do they do so?3. How robust are simulated convective-scale responses to CRF to changes in model framework, physical parameterization, and grid resolution?These questions will be addressed through a series of novel, process-oriented numerical model experiments using both regional and global convection-permitting modeling. Following a hypothesis-driven approach, model experiments will be executed to examine the transient response of clouds and deep convection (i.e., on time scales down to ~1 hour and less) to the removal and switch-on of cloud–radiative forcing (CRF). A novel aspect of the experiments is the selective inclusion/exclusion of CRF in specific populations of clouds and precipitation. This approach is motivated by the novel hypothesis that CRF in stratiform rain and anvil clouds plays a leading role in accelerating TC genesis. These experiments will be cast in both realistic and idealized frameworks to support both robustness and representativeness. The project will also entail studying model uncertainty tied to the numerical representation of hydrometeors and radiative forcing in distinct cloud populations, being among the first to examine and document this sensitivity at convective scales in the context of TC genesis. The results of this project are therefore expected to support the advancement of model prediction and forecasting across a broad range of scales and settings. Since CRF is recognized to be an important physical process on a wide range of physical scales, the new lessons arising from this work are expected to apply more broadly than the TC subject.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.

这项研究的首要目标是扩大我们对热带气旋（例如，飓风和台风）形成并增强。热带气旋是美国生命和财产损失的主要驱动力，沿海人口增长和气候变化加剧了这些影响。然而，尽管进行了几十年的研究，但在了解其形成和强化方面仍存在许多差距。因此，该项目解决了一个随着时间的推移只会变得更加紧迫的问题。研究人员将研究云和辐射之间的相互作用。最近的研究表明，这种相互作用加速了热带气旋的形成。这个项目将推进我们对这种反馈在单个雷暴系统尺度上的理解。通过这样做，这项研究最终将有助于改善热带气旋的预报，这反过来又有助于减轻登陆时的生命和财产损失。该项目还将直接支持早期职业科学家，研究生研究人员和本科生研究人员的领导力和专业发展。为了支持STEM教育的推进，项目团队将通过“Skype a Scientist”和其他虚拟活动开展K-12教育推广。为了解决与热带气旋（TC）云辐射反馈相关的科学空白，本研究将解决以下问题：1.在热带浅对流、深对流和层状降水中，对流尺度上的浮力、垂直运动和湿熵对云辐射强迫的响应是什么？2.在这些区域中，辐射反馈在加速对流高级发展和TC生成中有什么独特的作用，它们是通过什么机制这样做的？3.模拟的对流尺度对CRF的响应对模式框架、物理参数化和网格分辨率的变化有多强？这些问题将通过一系列新颖的，面向过程的数值模式实验，使用区域和全球对流允许建模来解决。在假设驱动的方法之后，将执行模型实验来检查云和深对流的瞬态响应（即，在时间尺度上降低到~1小时或更短）到云辐射强迫（CRF）的去除和开启。实验的一个新颖方面是在特定的云和降水群体中选择性地包含/排除CRF。这种方法的动机是一个新的假设，即CRF在层状雨和砧云起着主导作用，加速TC的成因。这些实验将在现实和理想化的框架中进行，以支持鲁棒性和代表性。该项目还将需要研究与不同云量中水凝物和辐射强迫的数值表示相关的模型不确定性，是第一批在TC成因背景下检查和记录对流尺度敏感性的项目之一。因此，预计该项目的结果将支持在广泛的尺度和环境中推进模型预测和预报。由于CRF被公认为是一个重要的物理过程，在广泛的物理尺度，从这项工作中产生的新的经验教训，预计将适用于更广泛的比TC的主题。这个奖项反映了NSF的法定使命，并已被认为是值得通过评估使用基金会的智力价值和更广泛的影响审查标准的支持。