It is important to understand how tropical cyclones (TCs) decay over the ocean as this is a critical
pre‐landfall stage. A modified exponential decay model (β model) with two parameters α and β is proposed. The
scale parameter α defines the decay scale, while the shape parameter β determines whether the decay rate
decelerates or accelerates over time. Global fittings indicate that around 40% of TCs exhibit decelerating decay
(β≤1), while the majority (about 60%) show accelerating decay (β>1). Correlation analysis reveals a strong
negative correlation between the scale parameter α and the initial Coriolis parameter (r = − 0.96) and a positive
correlation between the shape parameter β and the meridional component of the initial translation velocity
(r = 0.75). The β model provides a comprehensive understanding of how TCs decay with time and how
environmental conditions affect the decay scale and evolution.