Importance of Initial Vortex Wavenumber‐1 Asymmetries to Tropical Cyclone Intensification: Idealized Numerical Experiments

Abstract Considerable asymmetries in the tropical cyclones (TCs) inner core are frequently observed during the intensification phase. However, these asymmetric structures are often not well represented in the initialization of most operational forecasting models. In this study, we investigate the impact of initial vortex inner‐core asymmetries on TC intensification by conducting a series of idealized numerical experiments. We find that initial wavenumber‐1 asymmetries, which are closely linked to the vertical tilt of TC vortices, play a critical role in determining the timing of intensification onset. Specifically, TC intensification occurs only when the wavenumber‐1 asymmetries reach a specific configuration relative to the axisymmetric circulation. When the initial vortex lacks or inaccurately represents wavenumber‐1 asymmetries, additional time is required for adjustment of the vertical structure of TC vortices. This study suggests that better representation of wavenumber‐1 asymmetry in the initial structure of TC vortices could help improve TC intensity forecasts in numerical models.