On the Temporal Decay of Tropical Cyclones Over the Ocean

Abstract

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 ((Formula presented.) model) with two parameters (Formula presented.) and (Formula presented.) is proposed. The scale parameter (Formula presented.) defines the decay scale, while the shape parameter (Formula presented.) determines whether the decay rate decelerates or accelerates over time. Global fittings indicate that around 40% of TCs exhibit decelerating decay (Formula presented.), while the majority (about 60%) show accelerating decay (Formula presented.). Correlation analysis reveals a strong negative correlation between the scale parameter (Formula presented.) and the initial Coriolis parameter (Formula presented.) and a positive correlation between the shape parameter (Formula presented.) and the meridional component of the initial translation velocity (Formula presented.). The (Formula presented.) model provides a comprehensive understanding of how TCs decay with time and how environmental conditions affect the decay scale and evolution.