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TYPOLOGY

Forward Models

CONTACT POINT

Jorge RUIZ

ROLE

PhD Candidate

E-MAIL

jorge.ruiz@fmi.fi
support@eo-wimex.eu

← MODEL CATALOGUE

Snow2Phase

The Forward Model for Snow Phase Signature simulates the observed phase change due to snow changes between the InSAR pairs using the model proposed by Guneriussen et al 2001. The model is based on the increase in the optical path and travel time in presence of snow, as snow has a higher permittivity than air. The model requires the following inputs: sensor location, sensor central frequency, DEM and, alternatively, Snow Depth change and Snow Density or Snow Water Equivalent (SWE) change. This module produces a map with the simulated interferometric phase. Furthermore, an analysis of the phase sensitivity is presented.

The figure below depicts a representation of the model for phase change from snow change [1,2].  The line R a represents the path when only air is present, while R s  represents when snow is present. Since the permittivity of snow is higher the air, the wave suffers from refraction and observes an increase in the travel time and consequent travel time. 

The phase signature is calculated as [1]:

  • κ i  is the incoming radar beam vector.
  • ΔZ s is the snow depth change (m).
  • θ is the local incidence angle (m).
  • ϵ s   is the dielectric constant of the snow.
  • ρ s  is the snow density (g/cm^3) 
  • ϵ s =1+1.5995⋅ρs+1.861⋅ρs
  • Optional but recommended the addition of the term cosα, accounting for the local topographic slope (to be implemented).

TBD

InSAR: Interferometric Synthetic Aperture Radar

SWE: Snow Water Equivalent.

[1]. T. Guneriussen, K. A. Hogda, H. Johnsen, and I. Lauknes, “InSAR for estimation of changes in snow water equivalent of dry snow,” in Proc. IEEE Int. Geosci. Remote Sens. Symp. Taking Pulse Planet, Role Remote Sens. Manag. Environ. (IGARSS), vol. 2, Oct. 2000, pp. 463–466.

[2]. Leinss, Silvan & Wiesmann, Andreas & Lemmetyinen, Juha & Hajnsek, I.. (2015). Snow Water Equivalent of Dry Snow Measured by Differential Interferometry. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing. 8. 1-18. 10.1109/JSTARS.2015.2432031.