Accounting for Unresolved Clouds in a 1D Infrared Radiative Transfer Model. Part II: Horizontal Variability of Cloud Water Path

A 1D infrared radiative transfer model that handles clouds with subgrid-scale horizontal variability is developed and tested. It assumes that fluctuations in cloud absorptance optical depth κ across layers (and collections of layers) can be described by gamma distributions. Unlike homogeneous clouds, flux incident at a level inside a horizontally inhomogeneous cloud requires explicit computation of transmittance to all other levels in the …