Geometric Representation of Wet Snow through A Tri-Continuous Random Composite and Its Scattering Characterization with The Discrete Dipole Approximation

Building upon the previously developed bicontinuous random medium model for dry snow, this study presents an enhanced electromagnetic scattering model for wet snow, incorporating explicit treatment of water morphology. The model distinguishes among ice, water, and air phases, and further separates liquid water into discrete droplets and continuous water films through morphological thresholds during structural generation. To analyze the electromagnetic scattering behavior of this three-phase medium, the Discrete Dipole Approximation (DDA) method is employed to solve the volume integral equations. Feasibility of the DDA approach to characterize wet snow scattering is examined. This work then investigates the scattering properties and the effective permittivity of the random media composites at 37 GHz, considering variations in structural parameters, water content, and water morphology. The study further examines how these variations influence the brightness temperatures and backscatter coefficients arising from a wet snow layer. Model performance is then evaluated at Ku-and Ka-bands through comparisons with field observations from the NoSREx 2011 campaign, enabling validation for both active and passive microwave simulations, respectively. The wet snow electromagnetic scattering model developed in this research directly links the wet snow microstructure to its scattering behaviors, and it provides valuable insights for enhancing microwave remote sensing capabilities in snow-covered regions.