Collaborative Research: EAGER--Effect of Eddy Forcing Induced by Eyewall and Rainband Convection on Tropical Cyclone Rapid Intensification

本研究旨在加深我们对控制热带气旋加强的内部动力学的理解，并提高对热带气旋强度快速变化的预报技巧。该项目的结果和产品可以立即在TC预测的业务模型中实施，传播到更广泛的TC建模社区，并用于首席研究员(PI)S关于TC理论和应用的课程教学。该项目支持一名博士后研究员。该项目的教育目标是通过博士后研究人员和研究生/本科生的参与来培养和教育下一代科学家。传统的热带气旋增强观点认为绝对角动量是摩擦层上方的物质守恒量。这项研究试图证明与眼壁和雨带对流有关的涡旋过程是方位向平均角动量守恒的唯一强迫。正是这种强迫为触发和驱动TC的快速强化(RI)提供了一种终极机制，这是经典的TC强化理论无法解释的。在目前业务模式的分辨率下，PI表明，与对流相关的次网格尺度(SGS)强迫对TC增强，特别是RI具有重要影响。如何在热带气旋内核区产生一个真实的SGS强迫是湍流混合参数化中的一个新的挑战，这是以前没有探索过的。这个项目最重要的特点是：(1)促进我们对与眼壁和雨带对流相关的涡流强迫在调制TC强度变化中的作用的理解，以及(2)发展物理上可靠的参数化，以在用于TC预测的数值模式中表示与PBL以上的对流相关的次网格尺度强迫。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 research seeks to advance our understanding of internal dynamics in governing Tropical Cyclone (TC) intensification and improve forecasting skills for rapid change of TC intensity. The results and products of this project can be immediately implemented in operational models for TC prediction, disseminated to the broader TC modeling community, and used in Principal Investigator (PI)'s course teaching in TC theories and applications. The project supports a postdoctoral researcher. The educational goal of the project is to train and educate the next generation of scientists with the engagement of postdoctoral researcher and graduate/undergraduate students.The conventional view of Tropical Cyclone (TC) intensification regards the absolute angular momentum as a materially conserved quantity above the friction layer. This study seeks to demonstrate that the eddy process associated with eyewall and rainband convection serves as a sole forcing for the azimuthal-mean angular momentum conservation. It is this forcing that provides an ultimate mechanism for triggering and driving Rapid Intensification (RI) of TCs that cannot be explained by the classic TC intensification theories. At the current resolution of operational models, the PIs demonstrate that the sub-grid scale (SGS) forcing above the PBL associated with convection poses an important bearing on TC intensification, especially RI. How to generate a realistic SGS forcing aloft in the TC inner-core region is a new challenge in turbulent mixing parameterization that has not been previously explored. The most important features of this EAGER project are: (1) advance our understanding of the role of eddy forcing associated with eyewall and rainband convection in modulating intensity change of TCs and (2) develop physically robust parameterization to represent sub-grid scale forcing associated with convection above the PBL in numerical models used for TC prediction.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.