Radiometric measurements at L-band (1.4 GHz), collected in the Canadian Arctic in 2024, are used to study which type of model best reproduces the observations. While incoherent radiative transfer models are standard for sea ice thickness retrievals, they neglect phase interference effects. However, the observations analyzed here can only be explained when interference phenomena are explicitly included, requiring a coherent approach. To reduce uncertainties and ensure the robustness of the models, an optimal estimation method is used to determine snow and sea ice parameters consistent with the measured brightness temperatures and in situ measurements. The results show that the coherent model reproduces the observations substantially better than the incoherent formulation, yielding less than half the total cost with respect to the in situ measurements and being approximately 30,000 times more likely to explain the observations. These findings highlight the relevance of coherence effects at L-band, which are commonly neglected, at least in the context of local in situ measurements.