Spatial distributions of the total perturbed plasma density and associated with AW and GW wave modes are plotted in panels a-b and panels c-d, respectively. Iso-electronic contours driven by AW and GW modes are displayed in panels a and c, respectively. Perturbed density of the major ion constituent, ${\text{O}}_2^{+}$, is only displayed. Panels b and d show iso-ionic density contours associated with the AW and GW modes, respectively. Numbers on the contour lines refer to the plasma number densities in units of 10⁵ cm⁻³. Magnetic field vector, B₀, and wavenumber vector, k, lie in the plane of the paper. Relative orientation between B₀ and k for the AW and GW wave modes are shown in panels b and d, respectively. Angle between B₀ and k is 54° for the AW wave mode and −67° for the GW wave mode.