Investigating the Effect of Lake Ice Properties on Multifrequency Backscatter Using the Snow Microwave Radiative Transfer Model

Recent investigations using polarimetric decomposition and numerical models have helped to improve the understanding of how radar signals interact with lake ice. However, further research is needed on how radar signals are impacted by varying lake ice properties. Radiative transfer (RT) models provide one method of improving this understanding. These are the first published experiments using the snow microwave RT (SMRT) model to investigate the response of different frequencies (L-, C-, and X-band) at horizontal-horizontal (HH) and vertical-vertical (VV) polarizations using various incidence angles (20 degrees, 30 degrees, and 40 degrees) to changes in ice thickness, porosity, bubble radius, and ice-water interface roughness. This is also the first use of SMRT in combination with a thermodynamic lake ice model. Experiments were for a lake with tubular bubbles and one without tubular bubbles under difference scenarios. An analysis of the backscatter response to different properties indicates that increasing ice thickness and layer porosity have little impact on backscatter from lake ice. X-band backscatter shows increased response to surface ice layer bubble radius; however, this was limited to other frequencies except at shallower incidence angles (40 degrees). All three frequencies display the largest response to increasing root mean square (rms) height at the ice-water interface, which supports surface scattering at the ice-water interface as being the dominant scattering mechanism. These results demonstrate that the SMRT is a valuable tool for understanding the response of backscatter to changes in freshwater lake ice properties and could be used in the development of inversion models.

Automated summary

Recent investigations have used polarimetric decomposition and numerical models to study the interaction between radar signals and lake ice. This study is the first to use the snow microwave RT (SMRT) model to explore how different frequencies and polarizations are affected by changes in ice properties. The results show that the response of backscatter is influenced by surface ice layer bubble radius and ice-water interface roughness, indicating that surface scattering at the ice-water interface is the dominant scattering mechanism. The SMRT model is a valuable tool for understanding how backscatter responds to changes in freshwater lake ice properties and can be used to develop inversion models.