  Solar and thermal radiation are critical aspects of planetary climate, with
gradients in radiative energy fluxes driving heating and cooling. Climate
models require that radiative transfer tools be versatile, computationally
efficient, and accurate. Here, we describe a technique that uses an accurate
full-physics radiative transfer model to generate a set of atmospheric
radiative quantities which can be used to linearly adapt radiative flux
profiles to changes in the atmospheric and surface state -- the Linearized Flux
Evolution (LiFE) approach. These radiative quantities describe how each model
layer in a plane-parallel atmosphere reflects and transmits light, as well as
how the layer generates diffuse radiation by thermal emission and by scattering
light from the direct solar beam. By computing derivatives of these layer
radiative properties with respect to dynamic elements of the atmospheric state,
we can then efficiently adapt the flux profiles computed by the full-physics
model to new atmospheric states. We validate the LiFE approach, and then apply
this approach to Mars, Earth, and Venus, demonstrating the information
contained in the layer radiative properties and their derivatives, as well as
how the LiFE approach can be used to determine the thermal structure of
radiative and radiative-convective equilibrium states in one-dimensional
atmospheric models.
