Earth thermophysics is a branch of
geophysics that uses the naturally occurring surface temperature as a function of the cyclical variation in solar radiation to characterise planetary material properties. Thermophysical properties are characteristics that control the
diurnal, seasonal, or climatic surface and subsurface temperature variations (or thermal curves) of a material. The most important thermophysical property is
thermal inertia, which controls the amplitude of the thermal curve and
albedo (or
reflectivity), which controls the average temperature. This field of observations and computer modeling was first applied to
Mars due to the ideal atmospheric pressure for characterising granular materials based upon temperature. The
Mariner 6,
Mariner 7, and
Mariner 9 spacecraft carried thermal infrared
radiometers, and a global map of thermal inertia was produced from modeled surface temperatures collected by the
Infrared Thermal Mapper Instruments (IRTM) on board the
Viking 1 and 2 Orbiters. The original thermophysical models were based upon the studies of lunar temperature variations. Further development of the models for Mars included surface-atmosphere energy transfer, atmospheric back-radiation, surface emissivity variations, CO2 frost and blocky surfaces, variability of atmospheric back-radiation, effects of a radiative-convective atmosphere, and single-point temperature observations. ==References==