Examining the Rainfall Distribution and Asymmetries during the Landfalling Process of Tropical Cyclones

由强降雨引起的内陆淡水洪水一直是登陆飓风或热带气旋造成的最致命和代价最高的灾害之一。与对热带气旋路径的认识和预报有较大进展和对气旋强度变化的研究进展不大相比，热带气旋的定量降水预报仍然是一个具有挑战性的问题，进展甚微。本项目旨在通过研究登陆热带气旋与大气环境的相互作用，加深对热带气旋降水分布的认识，并改进热带气旋登陆过程中的定量降水预报。首席调查员将培养一名研究生参与这一研究项目，其中特别考虑到妇女和代表不足的少数族裔学生。登陆TCS的降水预报最具挑战性的不仅是降水的强度和范围，而且是降水的空间分布，特别是雨量最大的地区。热带气旋降水的分布和不对称性是与热带气旋引发的内陆洪涝和气旋尺度变化密切相关的重要特征。这项工作的总体目标是通过对长期卫星观测的统计分析，了解TCS登陆过程中降水的分布、演变和不对称性。本项目将研究在登陆前、登陆期间和登陆后影响登陆热带气旋降雨模式变化的物理过程，以及登陆与远洋登陆热带气旋的物理过程。在这些过程中要考虑的因素包括日变化、温带过渡和其他环境条件，如垂直风切变、总有效湿度和海面温度。这项研究将通过研究登陆热带气旋过程中降水变化的物理过程以及对登陆热带气旋的环境影响，填补我们对热带气旋降水演变的科学认识的一个关键空白。更好地了解这些热带气旋特征对于改进登陆气旋预报至关重要。这一奖项反映了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。

Inland freshwater flooding induced by heavy rainfall has been one of the most deadly and costly disasters produced by landfalling hurricanes or tropical cyclones (TCs). In contrast to the great progress in understanding and predicting TC tracks and moderate progress in TC intensity changes, quantitative rainfall forecast of TCs is still a challenge issue, and little progress has been made. This project seeks to advance our understanding of TC rainfall distribution by focusing on interactions between landfalling TCs and the atmospheric environment and to improve quantitative rainfall forecast of TCs during TC landfall. The principal investigator will foster involvement of a graduate student with particularly consideration of women and underrepresented minority students in carrying out this research project. The most challenging aspect of predicting rainfall in landfalling TCs is not only the intensity and the extent but also the spatial distribution of precipitation especially the heaviest rainfall area. The distribution and asymmetries of TC rainfall are important features inherently linked to TC-induced inland flooding and TC size changes. The overall goal of the work is to understand distribution, evolution, and asymmetries of rainfall during landfalling processes of TCs through statistical analyses of long-term satellite observations. This project will examine physical processes that influence changes of rainfall patterns for landfalling TCs in before, during, and after landfall stages, and for landfalling versus over-ocean TCs. Factors to be considered in these processes include diurnal variation, extratropical transition, and other environmental conditions such as vertical wind shear, total available moisture, and sea surface temperatures. The research will fill a critical gap in our scientific understanding of TC rainfall evolution by focusing on physical processes of precipitation changes during landfalling TCs and environmental impacts on landfalling TCs. A better understanding of these TC features is essential for improving landfalling TC forecasts.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.