Incorporating Eyewall Replacement in the Physics-based Tropical Cyclone Rainfall Risk Assessment under a Changing Climate

Description

Tropical cyclones (TCs) have caused large numbers of fatalities and vast economic loss, making them one of the most expensive weather disasters. With anthropogenic climate change, the probability of the most intense TCs, as well as associated rainfall, storm surge and inland flooding, is likely to increase, posing increasing challenges to coastal communities around the world. Recent infamous TC rainfall and flooding events make us wonder whether these extreme events, rarely recorded in decades, may have become the ‘new normal’ in the changing climate.The physics-based TC risk assessment framework aims to quantify the risks of the worst-case scenarios by generating large numbers (~104) of synthetic TCs across the point of interest, and estimate the probability associated with the hazards using Monte Carlo simulations. The framework has been widely used to estimate TC hazards in the U.S. and the identify potentially large risks of unexpected ‘grey swan’ TCs for highly vulnerable coastal regions. Compared with real-time forecasting (lead time of a few days), the risk assessment of extreme TC events is of crucial importance to strategic engineering design and urban planning on the time scale of decades or centuries.This research aims to incorporating eyewall replacements cycles (ERC), a fundamental change in storm structure and intensity that observed to occur in over 70% of the most intense TCs into the physics-based TC rainfall risk assessment schemes for the first time. Our previous work on TC rainfall modeling and a simple diagnostic of storm undergoing ERC provide a handy tool in incorporating ERC, a widely believed complicated process, into the framework of TC risk assessment. Building upon our previous efforts, this project plans to 1) build a detailed long-term dataset of observed ERC; 2) Incorporate ERC in the physics-based TC rainfall model; 3) improve the modeling of rapid intensification by taking ERC into account; and 4) investigate the effects of ERC on storm surge. The outcome of this project is expected to yield better understanding and representation of the rainfall risk of landfalling TCs in a changing climate, facilitating more strategic management of TC hazards by engineers, urban planners, stakeholders and government agencies.