<p>Explosive cyclones (ECs) are rapidly intensifying subtropical cyclones that can develop within a short time and pose considerable threats to coastal areas in middle and high latitudes. Gaining a comprehensive understanding of their formation, evolution, and mechanisms of explosive development is essential for improving forecasts of extreme weather events and mitigating associated impacts. Potential vorticity (PV), which is closely related to cyclone dynamics, serves as a valuable diagnostic tool in the study of ECs. In this study, two wintertime ECs of differing intensity over the Northwestern Pacific Ocean are analyzed to examine how different atmospheric processes influence PV generation and the rapid development of ECs. The maximum deepening rates of the two ECs are 2.81 Bergeron (called EC1) and 1.52 Bergeron (referred to as EC2). Results indicate that different stages of EC evolution are closely associated with PV tendency changes at different atmospheric levels. Using the PV tendency equation, during the explosive development of EC1, latent heat release may trigger the downward propagation of upper-level PV. For EC2, latent heat release notably enhances low-level PV, directly contributing to its rapid intensification. To validate these findings, sensitivity tests are conducted using the Weather Research and Forecasting model, with latent heat release turned off in the microphysical scheme for both cases. The results confirm the crucial role of latent heat release in generating low-level PV, further revealing that latent heat release contributes more to the explosive development of EC2 than that of EC1.</p>