Abstract: This paper proposes a criterion for layering transonic static ground effects based on studying the pitch oscillation encountered in electromagnetic-assisted near-ground takeoff using the NACA0012 airfoil. The flow patterns and aerodynamic characteristics in each layer were analyzed first. Subsequently, the influence of ground effects and reduced frequencies on pitch hysteresis properties was studied, focusing on the mechanism of the variations of hysteresis loop shape, steering, and fullness. The results indicate that the difference between the contraction ratio of the flow channel under the airfoil and the isentropic limit is an important factor for layering ground effects and determining flow patterns. Under the influence of the angle of attack, the transonic static ground effects can be categorized into three layers, the first featuring unblocked flow, the second with alternating unblocked and choked flows, and the third characterized by completely choked flow. Correspondingly, the near-ground pitch hysteresis characteristics also exhibit a hierarchical pattern. In the first layer, the hysteresis properties resemble those in free space due to the relatively weak ground effect. In the second layer, as the ground effect strengthens, the oscillating shock wave S2 subjected to the blockage effects is either stationary or approaches the trailing edge, leading to a reduction and translation of the hysteresis loop, respectively. In the third layer, the intensified congestion and overflow result in significant differences between the oscillating shock waves S1 and S2 at positive angles of attack but less differences at negative angles of attack, transforming the hysteresis loop shape from elliptical to "water droplet". Increasing the reduction frequency can transform the hysteresis loop back into an elliptical shape. Moreover, pitch hysteresis characteristics in different layers share similarities, such as the counterclockwise rotation of the moment hysteresis loops, consistent direction changes in the lift hysteresis loop with the sign of the curve phase, quasi-steady state low-frequency pitching, and strong hysteresis at high-frequency.