Browsing by Author "Nanda Kumar Sreeletha, Vishnu Nandan"

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    Multi-Frequency Microwave Interactions of Snow-Covered Arctic First-Year Sea Ice
    (2018-08-20) Nanda Kumar Sreeletha, Vishnu Nandan; Yackel, John J.; Else, Brent G. T.; Hall-Beyer, Mryka C.; Kim, Jeong Woo; Tonboe, Rasmus Tage
    In this thesis, the thermophysical, dielectric and Ku-, X- and C-band polarimetric microwave properties of relatively smooth snow covered first-year sea ice (FYI), from late-winter to pre-early melt onset thermodynamic regime are investigated. Fully-polarimetric microwave backscatter data acquired from a unique, surface-based multi-frequency (Ku-, X- and C-band) scatterometer system is used near-coincident with in situ snow thermophysical measurements, to investigate thermodynamic and electrical state of snow covered FYI. Using a first-order microwave backscatter model, a multi-frequency framework is theoretically established to determine the dominant snow thermophysical properties sensitive to the modeled microwave backscatter, at Ku-, X- and C-band frequencies. Multi-frequency microwave observations acquired from the scatterometer system are then used to inter-compare with modeled backscatter, to investigate the potential of the surface-based system to determine the thermodynamic and electrical state of snow covered FYI, at diurnal and temporal scales, from late-winter to pre-early melt onset. A unique frequency-dependent polarimetric parameter is developed to characterize frequency-dependent changes in microwave backscatter, as a function of snow thickness, polarization and incidence angle. Theoretical and observational findings indicate significant influence of snow salinity affecting microwave propagation through snow covers on FYI, for all three frequencies. These findings are utilized semi-empirically to develop a thickness-dependent snow salinity correction factor to improve FYI freeboard and thickness measurement retrievals from space-borne radar altimeters, operating at Ku-band.