Quantifying drivers of long-term changes in tropical cyclone intensification rates over the North Atlantic using the EBDS model

Abstract Tropical cyclone (TC) intensification rate (IR) critically influences TC intensity, yet the key factors governing its long-term variations over the North Atlantic (NA) remain poorly understood. This study addresses this gap using a simplified energetically based dynamical system model that explicitly separates and quantifies dynamical and thermodynamic influences. A pronounced dipole pattern is identified in TC IR trends over the past four decades, characterized by decreases (increases) in the northwest (southeast) NA. While thermodynamic factors have generally become more favorable for intensification across the entire NA, dynamical factors, primarily vertical wind shear, exhibit a dipole trend closely aligned with observed IR changes. Quantitative analyses indicate that the decreasing TC IR in the northwest NA is primarily driven by deteriorating environmental dynamical conditions linked closely with the Atlantic Multidecadal Oscillation. Conversely, the IR increase in the southeast NA is mainly attributable to enhanced thermodynamic conditions associated with global warming. These results highlight region-specific drivers of long-term changes in TC intensification, providing insights for improving future projections.