Tropical Cyclone Frequency: The Role of Precursors and the Large-Scale Environment
Prof. Christina M. Patricola
Iowa State University
Monday September 22, 2025, 2 PM ET
Abstract:
The annual number of global tropical cyclones (TCs) has been relatively constant from year-to-year in the historical record; however, the reason remains unknown. Furthermore, there is no consensus regarding future changes in global TC frequency. To work toward solving this problem, we investigated two possible controls on TC frequency, specifically, TC precursor disturbances, or “seeds”, and the large-scale environment. In the first part of this talk, we investigate how the typical Atlantic TC precursor, African easterly waves (AEWs), influences seasonal Atlantic TC frequency and landfall using large-ensembles of regional model simulations in which AEWs were prescribed or suppressed. In addition, we explore what other types of seeds generate TCs in the absence of AEWs. We then investigate to what extent AEW characteristics and/or environmental conditions drive Atlantic TC activity using regional model experiments in which AEWs were strengthened or sea surface temperatures were warmed. Next, we analyze the relationship between TC seed frequency and TC frequency in historical and future climates using simulations from the High Resolution Model Intercomparison Project. Finally, we examine connections between global TC frequency and modes of climate variability in observations. Altogether, this research indicates that the large-scale environment is a dominant control on TC frequency, with TC seeds playing a role in shaping TC characteristics.
Biosketch:
Christina Patricola is an Associate Professor in the Department of the Earth, Atmosphere, and Climate at Iowa State University and an Affiliate at Lawrence Berkeley National Laboratory. She serves as an editor of Geophysical Research Letters. Christina earned her PhD in Atmospheric Science from Cornell University in 2010 and was a postdoctoral researcher at Texas A&M University. Before joining Iowa State, she was a Research Scientist at Lawrence Berkeley National Laboratory. Her research interests include climate variability and change, extreme weather events, and numerical modeling. https://faculty.sites.iastate.edu/cmp28/
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