[P-PS06] 火星と火星衛星

[PPS06-13] Ultra-fast Kelvin wave packets in Mars' Atmosphere and their Interactions with Tides as Viewed by MAVEN/NGIMS and MRO/MCS

*Federico Gasperini¹、Joseph Hughes¹、Jeffrey M Forbes²、Edward MB Thiemann³ (1.Orion Space Solutions、2.Univeristy of Colorado Boulder 、3.Laboratory for Atmospheric and Space Physics)

キーワード：Mars Upper Atmopshere, Tides and Waves, Vertical Coupling, MAVEN , MRO

Atmospheric waves with different temporal and spatial scales play a critical role in coupling the lower and upper atmospheres of Mars and cause large perturbations. These waves include solar tides and ultra-fast Kelvin waves (UFKWs). Solar tides are global temperature, density, and wind oscillations originating from the daily cyclic absorption of solar energy in an atmosphere; while UFKWs are eastward-propagating global-scale Kelvin waves with periods from about 2 to 6 days that are capable of extending well into Mars' thermosphere. These waves can interact in a nonlinear way to produce secondary waves that propagate away as independent waves. These secondary waves are important because they can add significant variability in longitude and time to Mars' aerobraking region. Here, we analyze over 5 years of thermospheric densities from MAVEN/NGIMS and over 2 years of temperatures from MRO/MCS to show the critical importance that UFKWs and their nonlinear interactions play in Mars' thermosphere. We demonstrate that the tides, the UFKW, and the secondary waves from their interactions (a) are responsible for up to 50-80% of the longitudinal variability in the aerobraking region, (b) grow twofold in amplitude from 150 km to 200 km, and (c) are likely to propagate from the lower atmosphere. These results demonstrate that, similarly to Earth, 2.5- to 4.5-day UFKW packets and secondary waves from their nonlinear interactions produce significant longitudinal variability in Mars' thermosphere and need to be accounted for to anticipate effects due to wave forcing during future Mars’ aerobraking operations.