The issue of reflectance is fundamental to climate science because the quantity of energy is always conserved. Therefore, a surface with an emissivity of <1 (a grey-body) will always report a S-B temperature that is lower than the planetary emission temperature, because the planetary radiant emission temperature that is seen externally incorporates all the surface solar reflectance energy flux that has been converted to thermal energy by the presence of the atmosphere.
3.5 Estimation of Mars Global Surface Emissivity.
For the purposes of the modelling analysis presented here it has been assumed that the Global Octon Nighttime temperature of 202.5 Kelvin for MY29 [6] is a function of the average surface emittance of Mars (Table 5). The proposition being applied is that the unlit nighttime surface acts as a radiator that exits thermal radiant energy directly to space via an unimpeded atmospheric window. Further that the diurnal temperature range for Mars is generated solely by the process of adiabatic thermal enhancement, because the diabatic thermal radiant opacity of the semi-transparent Martian atmosphere is effectively energy neutral. Based on this proposition applying the Vacuum Planet Equation with a global average solar irradiance of 109.9 W/m2 reports an emissivity of 0.87 (Table 8) as the surface flux parameter that generates an average nighttime surface temperature of 202.5 Kelvin (Table 5).