Do rapidly and non-rapidly intensifying tropical cyclones represent two different dynamical regimes

Abstract Rapid intensification (RI) of tropical cyclones (TCs) poses a major challenge in intensity forecasting and is a key contributor to the observed bimodal distribution of cyclone peak intensities. However, it remains unclear whether RI represents a distinct dynamical process. Here, we use lag plot (phase space) analysis from nonlinear dynamical systems theory to examine the underlying dynamics of RI and non-RI cyclones. Case studies of Typhoon Yagi (RI) and Typhoon Bebinca (non-RI) that made landfall in southern China in September 2024, combined with statistical analyses of a global cyclone dataset (1990–2021), reveal systematic differences in phase trajectories and correlations between lifetime maximum intensity (LMI) and intensification time. Our findings suggest that RI is not merely an amplification of normal intensification but represents a distinct dynamical regime, characterised by a transient intensification process, rather than the approximately steady intensity growth of the non-RI cyclones. A simple trend-persistence model is used as a dynamical diagnostic to examine error growth in the two regimes.