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

这项研究的首要目标是扩大我们对热带气旋(如飓风和台风)如何形成和加强的理解。热带气旋是美国生命财产损失的主要驱动因素，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，但在理解它们的形成和强化方面仍然存在许多空白。因此，这个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。这个项目将在单个雷暴系统的尺度上促进我们对这种反馈的理解。通过这样做，这项研究最终将有助于改进对热带气旋的预测，这反过来将有助于减少它们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。为支持推进STEM教育，项目组将通过Skype a Science和其他虚拟活动进行K-12教育推广。为了解决与热带气旋(TCS)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、深层对流和层状降雨中，浮力、垂直运动和湿熵对对流尺度上的云辐射强迫(CRF)有何响应？2.辐射反馈在这些机制中在加速对流高尺度发展和TC形成方面有何独特作用，他们是通过什么机制(S)做到这一点的？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大的稳健性？这些问题将通过一系列新颖的、面向过程的数值模式实验来解决，使用区域和全球对流允许的模式。按照假设驱动的方法，将进行模式实验，以考察云和深对流(即在时间尺度上降至~1小时或更短)对云辐射强迫(CRF)移除和启动的瞬时响应。实验的一个新方面是在特定的云和降水群体中选择性地包含/排除CRF。这种方法是由一种新的假设所推动的，即层状雨和砧状云中的CRF在加速TC的生成方面起着主导作用。这些实验将在现实和理想的框架中进行，以支持稳健性和代表性。该项目还将需要研究与不同云群中水流星和辐射强迫的数字表示有关的模型不确定性，是在热带气旋形成的背景下第一批检查和记录对流尺度上的这种敏感性的项目之一。因此，预计该项目的结果将支持在广泛的规模和环境中推进模型预测和预测。由于CRF在广泛的物理尺度上被认为是一个重要的物理过程，从这项工作中产生的新经验预计将比TC主题应用得更广泛。该奖项反映了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。

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.