A new approach to modeling ice crystal aggregates and its implications for radar remote sensing

Backscattering cross sections of model ice crystal aggregates are computed at 35.6 GHz using the generalized multiparticle Mie (GMM) method and compared against a commonly used equivalent dielectric model (also referred to as the “soft sphere” or the “bulk” model). It is shown that the bulk model underestimates the backscattering cross sections by 7 to 20 dB over aggregate sizes from 3 to 19 mm. This raises concerns about using bulk models for the interpretation of millimeter wave radar measurements of ice clouds and snow.