Collaborative Research: On the Intensity and Size Relationship of Tropical Cyclones

热带气旋是破坏性最强的自然现象，每年造成大量人员伤亡和巨大的经济损失。它们的强度和大小是评估TC严重程度和潜在危害的两个最重要的矩阵，但它们之间的关系尚不清楚，难以预测。对热带气旋强度-尺度关系的进一步理解将有助于进一步改进对热带气旋强度和尺度的业务预报。这些改进反过来将帮助沿海社区为最大的潜在损害做好准备，并导致拯救生命和最大限度地减少财产损失。该项目将在大气动力学、建模和数据科学领域培训两名博士生和一名博士后，并支持STEM教育，方法是与一名本科生合作，根据项目所获得的知识对TC强度和大小进行实验预报。研究结果和实验预测将通过同行评议的出版物传达给科学界，通过课堂教学和课程开发传达给大学生，并通过网站和推特账户传达给普通公众。该项目是在国家自然科学基金资助的EARGER项目的基础上，结合绝对角动量(AAM)和地面拖曳造成的AAM损失，提出了TC地面风径向廓线的“有效绝对角动量”(EAAM)不变量模式。本项目的主要目的是探索大气气旋的径向损失和eAAM值与环境因子的相关性，以便eAAM模型能更好地解释观测到的热带气旋强度-尺度关系的复杂性和丰富的多样性。本研究以中心假说为指导，以三个基于过程的工作假说为基础。在这个框架下，不同的eAAM值是由环境条件决定的AAM向内径向损失的不同造成的。通过6组A-B系列的数值试验，研究了AAM和eAAM的内向径向损失率与环境条件的关系。A系列使用的是云模式版本1(CM1)模式，B系列使用的是允许云版的天气研究和预报(WRF)模式。最终的环境相关eAAM模型将通过要求eAAM使用观测风速信息预测的TC风速和eAAM使用观测风速信息预测的TC风速与其观测对应物高度一致(在观测不确定范围内)进行验证。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。

Tropical cyclones (TCs) are the most destructive natural phenomena, causing many casualties and enormous economic loss every year. Their intensity and size are the two most important matrics for assessing TC severity and potential hazards but their relation is not well understood and challenging to be predicted. The improved understanding of TC intensity-size relation will shed insights into how operational forecasts for TC intensity and size could be further improved. These improvements will in turn help coastal communities to prepare for the maximum potential damage and lead to saving lives and minimizing the losses of properties. This project will train two Ph.D. students and a postdoc in fields of atmospheric dynamics, modeling, and data science, and support STEM education by working with an undergraduate student to launch experimental forecasts for TC intensity and size based on the knowledge gained from the project. The research findings and experimental forecasts will be communicated to the science community via peer-reviewed publications, to college students via classroom teaching and curriculum development, and to general public via website and twitter accounts. This project is built on the knowledge and insights gained from a previously NSF-funded EAGER project, which put forward a radial invariant model of “effective absolute angular momentum” (eAAM) for radial profiles of TC surface winds by combining the absolute angular momentum (AAM) and the loss of AAM due to surface drags. The main goal of this project is to explore the dependencies of radial loss of AAM and eAAM values on environment factors so that the eAAM model would better explain the observed complexity and rich diversity of TC intensity-size relation. This research is guided by the central hypothesis substantiated by three process-based working hypotheses. Under this framework, different eAAM values result from differences in the inward radial loss of AAM that depends environment conditions. The central question of how the inward radial loss rate of AAM and eAAM are related to environment conditions is investigated through 6 sets of A-B series numerical experiments using the Cloud Model Version 1 (CM1) model for the A-series and cloud-permitting version of the Weather Research and Forecast (WRF) model for the B-series. The resultant environment-dependent eAAM model will be validated by requiring that both the eAAM-predicted TC winds using observed size information and the eAAM-predicted TC sizes using observed wind information are highly in agreement (within observation uncertainties) with their observational counterpartsThis 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.