Abstract
Martian upper atmosphere warming reflects the energy-materials
interactions from the lower atmosphere layers. In this paper, we show a
new phenomenon that enhances Mars upper atmosphere density in the
equatorial region during the winter periods. First, both
accelerometer-derived density and NGIMS-measured species from MAVEN show
that the winter equatorial region has a secondary warming peak compared
with that of the high-latitude polar warming area. Second, the major
neutrals (CO2, Ar, CO, N2, and O) indicate that the phenomenon extends
at least up to 240 km during both day and night sides. Furthermore, the
topographic-related longitudinal structure emerged in the equatorial
sector indicates that the variations are more dynamical than we
expected. The warming found in this study suggest to be dust-related and
influenced by the evolution of the seasonal solar insolation. Both local
factors, upward small-scale gravity waves and CO2 IR-thermal effect
transfer, may play key roles in shaping the warming structure.