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https://doi.org/10.5194/egusphere-2023-974
https://doi.org/10.5194/egusphere-2023-974
05 Jun 2023
 | 05 Jun 2023

Roles of Tropical Waves in the Formation of Global Tropical Cyclone Clusters

The-Anh Vu and Chanh Kieu

Abstract. This study examines the role of tropical dynamics in the formation of global tropical cyclone (TC) clusters. Using theoretical analyses and idealized simulations, it is found that global TC clusters can be produced by the internal dynamics of the tropical atmosphere, even in the absence of landmass surface and zonal sea surface temperature (SST) anomalies. Our analyses of a two-dimensional InterTropical Convergence Zone (ITCZ) model capture indeed some planetary-scale stationary modes whose zonal and meridional structures can support the formation of TC clusters at the global scale. Additional idealized simulations using the Weather Research and Forecasting (WRF) model confirm these results in a range of aqua-planet experiments. Specifically, the examination of two common tropical waves including the equatorial Rossby (ER) wave and the equatorial Kelvin (EK) wave shows that ER waves could develop and maintain a planetary-scale stationary structure for a range of zonal wavenumbers [5–11], while EK waves do not. This numerical result is consistent with the ITCZ breakdown model and reveals some forcing structures that can support stationary "hot spots" for global TC formation. The findings in this study offer different insights into the importance of tropical waves in producing global TC clusters beyond the traditional explanation based on zonal SST anomalies.

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Short summary
Tropical cyclone (TC) formation has been well documented to possess distinct clusters globally....
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