Observations of Gravity Waves Propagating Through the Mesopause and the Lower Thermosphere Using Airglow in Southern Brazil

Abstract:

Gravity waves observed in the night airglow can be often seen at heights near the mesopause. Much less frequent are the cases where the same gravity wave is observed in the mesopause and in the thermosphere. One of the reasons for this is the absorption that occurs in the intermediate region. A whole year of airglow observations conducted in southern Brazil (29°26' S, 53°49' W) has been analyzed to investigate the gravity waves. The data was acquired by an all-sky imager using filters for sodium, 555.7, 777.4 and 630 nm oxygen emissions from March 2011 to April 2012. Preliminary results show more than 300 gravity waves observed mainly in the O5 and sodium layers. However, less than 10 cases were identified as waves observed both in O5 and/or sodium and in the O6 band (in the thermosphere). In those specific cases the waves have the same general horizontal propagation direction, toward N-NW. Further analyses concerning the parameters and similarities of this kind of gravity wave as well as the possible reasons for the preferred propagation direction will be discussed.