Scripps Institution of Oceanography

SIO Reference 59-73. In this work we complete the outline of the basic theory of directly observable irradiances1 in a plane-parallel medium X by formally deriving the principles of invariance which govern these irradiances and their associated reflectance and transmittance functions over arbitrary subslabs of X. The derivations hold for a completely general plane-parallel medium setting: The medium is arbitrarily stratified with reflecting boundaries, and has a given set of external and internal source conditions.