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.