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Coherence

Coherence: A measure of how little the radar phase changes between repeated passes; high coherence is essential for sharp tomographic reconstruction and deformation mapping.

Look Angle (θ)

Look Angle (θ): The tilt between the radar beam and the vertical; together with baseline and wavelength, it controls the achievable vertical resolution Δh ≈ λ R / (2 B⊥ sin θ).

Baseline (B⊥)

Baseline (B⊥): The sideways separation between two flight tracks; greater baselines widen the synthetic vertical aperture and sharpen Height Resolution.

Wavelength (λ)

Wavelength (λ): Physical length of one radar wave; long wavelengths (L-band ≈ 23 cm, P-band ≈ 70 cm) penetrate foliage or dry sand far better than short ones (X-band ≈ 3 cm).

Voxel

Voxel: The smallest 3-D element in a tomographic cube; it records echo strength from a specific azimuth-range-height cell, analogous to a pixel in 2-D imagery.

Tomographic SAR

Tomographic SAR (TomoSAR): A stack of slightly offset SAR passes treated as a vertical aperture so that the Doppler spectrum can be inverted, Voxel by Voxel, into a three-dimensional Back-scatter map.

Doppler Shift

Doppler Shift: The tiny change in echo frequency caused by the platform’s motion relative to scatterers ahead or behind the beam; SAR processors exploit these shifts to focus detail along track and, in tomography, to separate echoes coming from different heights.

Synthetic-Aperture Radar

Synthetic-Aperture Radar (SAR):  Side-looking radar flown on aircraft or satellites; by combining echoes gathered along the flight path it simulates an antenna hundreds of metres long and produces metre-scale images day or night, through cloud, smoke or vegetation.

ELA

ELA (Equilibrium Line Altitude) – Altitude on a glacier where annual snow gain equals melt; a sensitive climate indicator.

Research Links

This is our list of useful sites for further research. Here we have gazetteer sites, mapping sites and sites for academic reports.

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