Tropical cyclones and their precursors or "seeds"
Atlantic tropical cyclone (TC) genesis is strongly linked with African easterly waves (AEWs) on the weather time scale. However, the TC-AEW relationship is unclear on interannual to climate time scales, and it is unknown whether AEWs are necessary to maintain climatological TC frequency, that is, whether TCs are limited by AEWs. We investigated the impact of AEW suppression on seasonal Atlantic TC activity using a 10-member ensemble of regional climate model simulations in which AEWs were either prescribed or removed through the lateral boundary condition. The climate model experiments produced no significant change in seasonal Atlantic TC number, indicating that AEWs are not necessary to maintain climatological basin-wide TC frequency even though TCs readily originate from these types of disturbances. This suggests that the specific type of “seedling” disturbance is unimportant for determining basin-wide seasonal Atlantic TC number, and that in the absence of AEWs, TCs will generate by other mechanisms. The results imply that changes in the presence of AEWs may not be reliable predictors of seasonal variability and future change in Atlantic TC frequency.
- Patricola, C. M., Saravanan, R., & Chang, P. (2018). The Response of Atlantic Tropical Cyclones to Suppression of African Easterly Waves. Geophysical Research Letters, 45(1), 471-479.
This research was supported by the U.S. National Science Foundation and the U.S. Department of Energy Office of Science (BER RGMA program). High-performance computing resources provided by the Texas Advanced Computing Center (TACC) at The University of Texas at Austin and by the Texas A&M Supercomputing Facility.
We investigated the impact of suppressing AEWs using a 3-member ensemble of convection-permitting regional model simulations, in which AEWs were either retained or removed through the lateral boundary conditions. Suppressing AEWs did not substantially change seasonal TC number, but did influence TC intensity and genesis location. Suppressing AEWs produced stronger TCs and reduced (increased) TC genesis in the eastern Atlantic (Gulf of Mexico). These results provide robust evidence that AEWs may not be reliable predictors of basin-wide seasonal TC frequency. However, this research suggests that AEWs may influence TC tracks and landfall location.
- Danso, D. K., Patricola, C. M., & Bercos-Hickey, E. (2022). The Influence of African Easterly Wave Suppression on Atlantic Tropical Cyclone Activity in a Convection-Permitting Model. Geophysical Research Letters, 49, e2022GL100590.
This research was supported by the U.S. Department of Energy Office of Science (BER RGMA program) under Early Career Research Program Award Number DE-SC0021109 and under Award Number DE-AC02-05CH11231. High-performance computing resources provided by the National Energy Research Scientific Computing Center (NERSC).
- Bercos-Hickey, E., & Patricola, C. M. (2023). The Effects of African Easterly Wave Suppression by Wave Track on Atlantic Tropical Cyclones. Geophysical Research Letters, 50 (23), e2023GL105491.
- Bercos-Hickey, E., Patricola, C. M., Collins, W. D., & Loring, B. (2023). The Relationship Between African Easterly Waves and Tropical Cyclones in Historical and Future Climates in the HighResMIP-PRIMAVERA Simulations. Journal of Geophysical Research: Atmospheres, 128(7), e2022JD037471.
updated 3/13/2024