Distributions of wave damping altitude, ɀ_damping, and vertical wavelength at damping altitude, λ_ɀ(ɀ_damping), for AWs and GWs and are displayed in panels a-b and panels c-d, respectively. “AWs” and “GWs” represent three wave sets selected in acoustic branch and gravity branch, respectively. Vertical wavenumbers at lower boundary, $k_z^l$, are 0.11, 0.32, and 0.99 km⁻¹ for AWs and −0.07, −0.19, and −0.5 km⁻¹ for GWs. Horizontal wavelengths of selected wave modes range from 10 km to 300 km in intervals of 10 km.