Soil thermal inertia method by Murray and Verhoef
Soil_Inertia1.RdSoil_Inertia1 estimates the soil thermal inertia GAM from the
soil moisture content, using the empirical model of Murray and Verhoef
(2007) for thermal conductivity and a linear mixing model for volumetric
heat capacity. Used when options.soil_heat_method == 1 in the SCOPE
energy balance.