Fundamental Studies of Disturbed Tropical Cyclones: A Deeper Look into the Causes and Consequences of Asymmetric Structure Under Various Environmental Conditions

热带气旋造成全球沿海和岛屿社区的广泛破坏和生命损失。它们已经被研究了几十年，但还没有完全被理解。更多对热带气旋的物理了解将提高我们预测个别风暴行为和气候变化对风暴统计影响的能力。该项目旨在进一步深入了解热带气旋不对称的原因和后果，热带气旋不对称通常与螺旋雨带、倾斜和眼壁中涡有关。将讨论以下问题：环境条件控制主要不对称性的程度，产生或抑制不对称性的机制，以及不对称性对涡旋强度的影响。本项目将包括与简化(3层)和云系分辨率(CSR)热带气旋模式的补充研究。简化的模型将有助于对不同环境条件下普遍存在的不对称性进行有效的计算调查。此外，它还将被用来推进关于核心不稳定性(造成不对称性)和涡旋回弹(抗倾斜)的不发达理论。理论研究将集中于翻转环流、边界层耦合和与湿对流相关的非绝热强迫的作用。将研究改变地面交换系数、海面温度、中层相对湿度和积云参数化方案的影响。从简化模型得出的结论将与CSR模拟进行测试，并解释任何差异。将评估瞬时和持续不对称对涡旋强度的影响，部分通过轴对称和3D热带气旋模型的比较。该项目的资金将部分用于博士后研究人员的高级培训和指导。项目成果将通过大学研讨会、期刊出版物、会议报告和研究网页进行传播。

Tropical cyclones are responsible for extensive damage and loss of life in coastal and island communities around the globe. They have been studied for decades, but are not fully understood. Greater physical understanding of tropical cyclones will improve our ability to predict the behavior of individual storms and the effects of climate change on storm statistics. This project seeks further insight into the causes and consequences of tropical cyclone asymmetries, which are commonly associated with spiral rainbands, tilts and eyewall mesovortices. The following issues will be addressed: the extent to which environmental conditions control the dominant asymmetries, the mechanisms that create or suppress asymmetries, and the impact of asymmetries on vortex intensity.This project will involve complimentary studies with reduced (3-layer) and cloud-system resolving (CSR) tropical cyclone models. The reduced model will facilitate an efficient computational survey of prevailing asymmetries under different environmental conditions. Moreover, it will be used to advance underdeveloped theories of core instabilities (which create asymmetries) and vortex resilience (resistance to tilt). The theoretical studies will focus on the roles of overturning circulation, boundary layer coupling, and diabatic forcing associated with moist convection. The effects of varying the surface-exchange coefficients, sea-surface temperature, mid-level relative humidity and cumulus parameterization scheme will be examined. Conclusions derived from the reduced model will be tested against CSR simulations, and any differences will be explained. The impact of transient and persistent asymmetries on vortex intensity will be assessed, partly by comparison of axisymmetric and 3D versions of the tropical cyclone models.Funds for this project will be used in part for the advanced training and mentorship of a postdoctoral researcher. Project findings will be disseminated through university seminars, journal publications, conference presentations, and a research web page.