Energy balance and heating mechanisms of the Martian Upper atmosphere
with the NASA Ames MGCM.
Abstract
Mars present-day middle and upper atmosphere, above ~100
km, connects the deep atmosphere to the Martian space environment. This
region is important to understand for many reasons, including for more
general insights into the evolution of atmospheres, as a comparison to
other planetary atmospheres, and for current and future mission
development and interpretation. The middle/upper atmosphere is greatly
influenced by the physics of the lower atmosphere (water cycle, dust
cycle, waves, etc.) and the solar environment (solar magnetic activity,
solar events). It contains the upper branch of the overturning
meridional circulation and the transitional point of the main heating
source from near-IR to UV radiation. These influences feed on a
primitive property of an atmosphere: temperature. This work will break
down the radiative processes that drive the Martian’s thermal structure
above ~100 km as a function of latitude and season. We
demonstrate the on-going work on extending the NASA Ames Mars Global
Climate Model (MGCM), now using the NOAA/GFDL FV3 dynamical core. The
MGCM nominally extends from the surface up to ~80 km but
new physics packages will extend the MGCM’s vertical domain up to
~250 km. We present the heating and cooling mechanisms
that dominate this atmospheric region, discuss the parametrizations
used, the state of the seasonal/diurnal thermal structure, and finally,
we discuss the work in progress for the development and implementation
of physics schemes in our model.