A Unique Vertical Structure of Quasi-20-sol Waves Observed by the MCS on the Martian Atmosphere

In this study, we report a two-cell structure of quasi-20-sol waves (Q20SWs) in the Martian atmosphere and investigate its formation mechanism. The study is based on temperature data measured by the Mars Climate Sounder, and neutral wind and temperature data obtained from the Mars Global Circulation Model reanalysis data set. The two-cell structure is observed before the winter solstice in a latitude range from 55 degrees N to 65 degrees N in three consecutive Mars years (MY, MY30-32). The lower cell has a maximum amplitude of 9 K occurring at similar to 25 km, while the magnitude of the upper cell is much smaller with a peak amplitude of 5 K appearing at similar to 60 km. In the period from Ls180 degrees to Ls270 degrees, the peak amplitudes of the two cells are highly correlated with a correlation coefficient of 0.90, and the corresponding phases are shifted by similar to 180 degrees. The Eliassen-Palm (EP) flux and the EP flux divergence of the Q20SWs, and the zonal-wave available potential energy transfer between the zonal mean zonal flow and the Q20SWs are calculated. Our results suggest that the formation of the two-cell structure is likely due to the combined effects of the wave sources, the upward propagation of the Q20SWs from the lower cell, and the available potential energy transfer between the zonal mean flow and the Q20SWs.