Momentum flux characteristics of vertical propagating Gravity Waves

Abstract. Simultaneous observations of airglow intensity, rotational temperature, and wind data at São João do Cariri (36.31° W; 07.40° S) by Co-located photometer, all-sky imager, and meteor radar were used to study the characteristics of vertical propagating gravity waves (GWs). Using the photometer data, the phase progression of GWs with the same propagation period in the OI 557.7nm, O₂, NaD-line, and OH (6-2) emission layers were then used to determine the upward or downward vertical propagation of the waves. The vertical phase speed and wavelength are estimated using the wave period and phase difference at different altitude. From the O₂ and OH (6-2) rotational temperatures, the total energy and the momentum flux of the downward propagating GWs were determined. For the upward propagating GW only the momentum flux and potential energy were estimated due to lack of observed wind. Further analysis of the momentum flux for each of the two events revealed that the momentum flux and potential energy of the downward propagating GWs increases with decreasing altitude. On the contrary, the GW momentum and energy of the upward propagating waves increases with increasing altitude. Thus, clearly demonstrating the transfer of momentum flux and energy from the source to the sink. This characteristic difference can be used to careful analysis the changes in GWs energy propagation due to reflection of non-primary GWs.