Collaborative Research: Examining Cloud-Radiation Feedback at Convective Scales in Tropical Cyclones

The goal of this project is to expand understanding of how tropical cyclones (e.g., hurricanes and typhoons) form and intensify. Tropical cyclones are the leading driver of losses to life and property in the U.S., with coastal population growth exacerbating these impacts. However, despite decades of study, many gaps remain in understanding their formation and intensification. The project will examine the interaction between clouds and radiation as this interaction accelerates the formation of tropical cyclones and advance our understanding of cloud-radiation interaction at the scales of individual thunderstorms. This research will improve prediction of tropical cyclones which improves disaster resilience and helps reduce adverse impact on critical infrastructure, and damage to life and property. The project will also support the leadership and professional development of early-career scientists, graduate researchers, and undergraduate researchers. To address science gaps related to cloud–radiation feedback in tropical cyclones (TCs), this research will address the following questions: 1. What are the responses of buoyancy, vertical motion, and moist entropy to cloud–radiation forcing (CRF) on convective scales in tropical shallow convection, deep convection, and stratiform rainfall? 2. What are the unique roles of radiative feedback in these regimes in accelerating convective upscale development and TC genesis, and through what mechanism(s) do they do so? 3. How robust are simulated convective-scale responses to CRF to changes in model framework, physical parameterization, and grid resolution? These questions will be addressed through a series of novel, process-oriented numerical model experiments using both regional and global convection-permitting modeling. Following a hypothesis-driven approach, model experiments will be executed to examine the transient response of clouds and deep convection and the removal and switch-on of cloud–radiative forcing (CRF). This approach is motivated by the novel hypothesis that CRF in stratiform rain and anvil clouds plays a leading role in accelerating TC genesis. The award will also support studying model uncertainty tied to the numerical representation of hydrometeors and radiative forcing in distinct cloud populations. Results of this project are expected to support the advancement of model prediction and forecasting across a broad range of meteorological scales and settings. 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.