On the Relationship Between Stickiness in DMRT Theory and Physical Parameters of Snowpack: Theoretical Formulation and Experimental Validation With SNOWPACK Snow Model and X-Band SAR Data

This study aims at relating the stickiness parameter (tau) of the dense media radiative transfer theory in quasicrystalline approximation of Mie scattering of densely packed sticky spheres (DNIRT-QMS), to the physical parameters of the layered snowpack. A relationship has been derived to express tau, which modulates the attractive contact force between ice spheres, as a function of ice volume fraction (phi) and coordination number (n(c)). Since tau is not a measurable parameter, this is a step forward with respect to what is commonly made in the literature, where tau is assumed as an arbitrary parameter, generally ranging between 0.1 and 0.3, to fit simulated backscattering data with those measured. As a first validation, DMRT-QMS was integrated with the SNOWPACK model to simulate backscattering at X-band (9.6 GHz) driven by nivo-meteorological data acquired on a test area located in Monti Alti di Ornella, Italy. The simulations were compared with Synthetic Aperture Radar COSMO-SkyMed (CSK) satellite observations. The results show a significant agreement (R-2 = 0.68), although for a limited dataset of eight points in a unique winter season.