Dynamics of Rossby dipole with effect of scalar nonlinearity

• The evolutions of Rossby dipole vortex and its rotated type under the effects of scalar nonlinearity are studied.
• Scalar nonlinearity affects the blocking dipole more evidently than its minus counterpart.
• The competition between vector and scalar nonlinearity may lead to the seesaw evolution of the cyclone and anticyclone which consist the dipole.
• The rotation of the dipole’s symmetry axis can also result in the seesaw evolution.
• The influence of scalar nonlinearity is challenged by vector nonlinearity, background flows and the rotation of the initial field.

Based on the Petviashvili equation, dynamics of Rossby dipole with effect of scalar nonlinearity is discussed. It is shown that the final dynamics of Rossby dipole depends on many factors such as interaction of scalar nonlinearity, vector nonlinearity and background flows. The Rossby blocking dipole is affected by the scalar nonlinearity more evidently. The seesaw phenomenon is also observed in the Rossby dipole evolution due to the two nonlinearities balance or its rotation structure.