Simulations of the altimetric signal intensity from 2D layered air/snow/sea-ice rough interfaces

Abstract : Remote monitoring of the sea-ice thickness is one of the main objectives of the Cryosat mission. On the one hand, sea-ice thickness is derived from the measure of the freeboard of the ice, based on isostasy and assuming that the density of water, ice, as well as snow, are known. On the other hand, even if the snow load is known, the penetration of the electromagnetic waves into the snow strongly depends on the electrical and geophysical characteristics of the snow layer (density, temperature, permittivity, roughness). The remote sensing of the snow layer thickness (SLT) remains a real challenge and will be useful to correct for the snow load for converting freeboard measurements from satellite altimetry into sea-ice thickness. If dual frequency radar altimetric data show a good potential for remote sensing of snow and more generally of penetrating media, (Legrésy et al., 2005), providing the SLT from Ku band data alone is highly motivated by the orbit of Cryosat designed to cover the entire Arctic. A theoretical study, based on the 2D modelling of the scattering of electromagnetic waves by rough layered interfaces at normal incidence, has been carried out in order to investigate the capacity of snow penetration of Ku-band waves. The multi-layered model used in this study is based on the first-order small perturbation method (Afifi et al. 2010, 2012). Within its domain of validity, this approximate model allows a fast analysis of the multi-layered structures by means of analytical equations giving the scattered field and intensities. The total backscattered intensity IT is written as a sum of a coherent IC and a fluctuating IF contribution: IT = IC + IF IC is the coherent contribution to the total intensity coming from the scattering of the stack of layers, and IF is the fluctuating contribution which takes into account the first order roughness effects. The medium is considered as a stack of three layers, with two interfaces, air/snow and snow/ice. Several simulations have been conducted by varying the temperature, permittivity, roughness and thickness of each layer and the results are presented. More specifically, the influence of the snow thickness on the backscattering is analysed.
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Submitted on : Wednesday, September 11, 2013 - 7:35:51 PM
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  • HAL Id : hal-00861094, version 1

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Richard Dusséaux, Saddek Afifi, Monique Dechambre, Benoit Legresy. Simulations of the altimetric signal intensity from 2D layered air/snow/sea-ice rough interfaces. Proceedings of '20 Years of Progress in Radar Altimetry'. ESA SP-710, Sep 2012, Venice, Italy. ⟨hal-00861094⟩

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