To verify the feasibility of the atmospheric duct inversion and monitoring method based on automatic identification system signals, it is necessary to study and solve the forward problem, i.e., analyzing the impact of atmospheric ducts on the propagation of automatic identification system signals over the sea. This paper establishes a forward propagation model for automatic identification system signals under atmospheric duct conditions based on the parabolic equation method, analyzes the influence of atmospheric duct parameter variations on the propagation characteristics of automatic identification system signals, and verifies the feasibility of using automatic identification system signals to invert atmospheric ducts. This lays a theoretical foundation for monitoring atmospheric ducts using automatic identification system signals. This direction not only fills the gap in maritime atmospheric duct monitoring methods but also provides a new paradigm for low-cost, wide-coverage marine environmental remote sensing.