Historical and future tropical cyclone rainfall and flooding in the eastern US shaped by extratropical transition

Department of Hydrology and Atmospheric Sciences
 
4 pm on Thursday, October 21, 2021
Available via zoom
Contact the department for zoom details or to subscribe to the seminar email list
 
Maofeng Liu
Postdoctoral Research Associate, Rosenstiel School of Marine and Atmospheric Science, University of Miami

Abstract

Hurricane rainfall and resultant flooding pose a major threat to life and properties in the U.S. This talk highlights the prominent role of extratropical transition (ET), a process that can extend the hazard of a tropical cyclone (TC) to mid- and high-latitudes by providing the storm with additional baroclinic energy, in shaping TC rainfall and flooding properties in the eastern US. ET is a key contributing factor to the top four TCs producing the largest number of record flood events over the period of 1930-2017. 80% of the top 20 storms underwent ET process. Analyses of TC rainfall composite indicate the shift of symmetric TC rainfall to the northeastern quadrant over enlarged areas due to the interaction with mid-latitude baroclinic systems. Individual TCs are further presented to highlight the influence of ET on extreme TC rainfall.The second part of this talk focuses on the changing properties of ET storms under global warming. Despite insignificant change in basin-wide TC frequency in the North Atlantic in a warmer climate, the ratio of storms undergoing ET shows a significant increase due to more TC-favorable environment based on climate model simulations. One group of the increased ET storms propagates northeast toward Western Europe. The other moves northwest toward the northeast coast of the U.S. and leads to a striking increase in storm frequency and therefore TC rainfall. Analyses also suggest that ET storms produce increased rainfall rate under climate warming, due to both increased atmospheric water vapor and dynamic strengthening, which is further demonstrated by a regional dynamical model.

Bio

Image Maofeng Liu

Maofeng Liu received his Ph.D. from Princeton University and is currently working as a Postdoctoral Research Associate in the Rosenstiel School of Marine and Atmospheric Science at the University of Miami. He is broadly interested in climate change/sensitivity and its impact on climate extremes with a specific focus on hurricane rainfall and resultant flood hazards.