Understanding the Physical Processes Responsible for Different Rainfall Distributions Associated with Tropical Cyclone Landfall

Project: Research

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Tropical cyclone (TC) is one of the most devastating weather-related hazards, which may cause significant fatalities, property loss, and damage to infrastructure, etc. when it is close to land through its intense winds, heavy rain and storm surge. Among these three elements, the location of occurrence of heavy rain is the most difficult to predict because of our relative poor understanding of the mechanisms for the development of heavy rain associated with TCs, and the limited amount of data available.The World Meteorological Organization therefore endorsed in 2015 the establishment of a Research and Development Project [Understanding and Prediction of Rainfall Associated with Landfalling Tropical Cyclones (UPDRAFT)] to study the heavy rain phenomenon associated with TC landfall through field campaigns, data analyses and numerical simulations. This current proposed project will focus on contributing to one of the two objectives of this 5-year international project of which the PI is a member of the International Science Steering Committee, which is to enhance our understanding of the physical processes that lead to various rainfall distributions associated with TC landfall. Specifically, the objectives are as follows:(1)To document the effects of land surface characteristics and topography on the rainfall distribution as a TC makes landfall, and (2) To identify the role of environmental thermodynamic (such as moisture and convective instability) and dynamic (such as vertical wind shear) effects in modifying the rainfall distribution.While some previous studies have addressed these two issues, they were mostly based on case studies with limited amounts of observations, and therefore some outstanding questions remain unanswered. The data from the field campaigns in the UPDRAFT project will allow a much more complete examination of the dynamic and thermodynamic conditions related to the convection and rainfall distributions associated with TC landfall. The current proposal includes participation in the data collection during the field campaign, the subsequent data analyses and numerical simulations to address the two listed objectives. While the effects listed are not the only ones that can modify these distributions (others include, for example, large-scale synoptic flow patterns, internal dynamics and microphysical processes), it is expected that the results of this study will contribute towards an improved understanding of the physical processes responsible for the observed rainfall distributions associated with TC landfall, which may then contribute to improved accuracy of rainfall forecasts in numerical weather prediction models.


Project number9042541
Effective start/end date1/10/17 → …