CAREER: Understanding the Variability, Predictability and Changes of Tropical Cyclone Genesis Frequency in the North Atlantic: From Basin to Sub-basin Scales

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This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).North Atlantic (NA) tropical cyclones (TCs) cause devastating losses of life and property along our Eastern Seaboard. Owing to the small number of TCs in observations, our knowledge of the reasons behind the variations in TC genesis remains limited. This limitation has resulted in our failure, at times, to reasonably forecast seasonal basin-wide TC genesis frequency and in continuing challenges to predict seasonal TC genesis frequency on sub-basin scales. As such, having an improved understanding and better predictions of TC activity is societally beneficial. This project utilizes an unprecedentedly large number of high-resolution model simulations to explore NA TC genesis. These simulations greatly expand the input in data-sparse regions and improve TC incidence, allowing us to examine the fundamental processes that govern both basin-wide and sub-basin TC genesis frequency. The project results will help overcome difficulties in seasonal forecasts of TC tracks and landfall, given the enhanced information regarding the relation between preferred TC tracks and TC genesis location. The research will be integrated with activities to educate, train, and broaden the participation of students from underrepresented groups in Atmosphere, Ocean and Climate Sciences as well as to inform the broader community through public outreach. The project aims to advance the knowledge of the variability, predictability, and changes of both basin-wide and sub-basin TC genesis frequency over NA under different climates. The research objectives are to: (1) characterize the forced variability in TC genesis frequency that is driven by sea surface temperatures (SSTs) and the internal variability that arises due to the chaotic nature of the atmosphere, (2) assess the physical mechanisms underlying these two types of variability, and determine their impacts on the predictability of seasonal TC genesis frequency, (3) quantify the effects of global warming on the climatology of and trend in TC genesis frequency since the 1970s, and (4) explore how SST warming combined with a sizable greenhouse gas increase affects TC genesis frequency and evaluate the probabilistic changes in TC genesis frequency in warmer climates. These objectives will be achieved via dynamical diagnosis and statistical analysis of a very large ensemble of long-term, high-resolution simulations that accurately reproduce observed TC characteristics. This project will support the development of an interdisciplinary course to stimulate the interest of undergraduates in Atmosphere, Ocean and Climate Sciences. It will provide training for doctoral students, and hands-on research projects for underrepresented undergraduates from HBCUs and UNC Chapel Hill. The results will also be integrated into local high-school curriculum.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.