A spatially variable power law tropospheric correction technique for InSAR data

• Published in: Journal of geophysical research. Solid earth Vol. 120; no. 2; pp. 1345 - 1356
• Main Authors: Bekaert, D. P. S., Hooper, A., Wright, T. J.
• Format: Journal Article
• Language: English
• Published: 01.02.2015
• Subjects: atmosphere; InSAR; long wavelength; tectonic deformation; troposphere
• ISSN: 2169-9313; 2169-9356
• DOI: 10.1002/2014JB011558

Microwave signals traveling through the troposphere are subject to delays. These delays are mainly described by spatial and temporal variations in pressure, temperature, and relative humidity in the lower part of the troposphere, resulting in a spatially varying tropospheric signal in interferometric synthetic aperture radar (InSAR). Tropospheric correction techniques rely either on external data, often limited by spatial and temporal accuracy or can be estimated from the high‐resolution interferometric phase itself. However, current phase‐estimated correction techniques do not account for the spatial variability of the tropospheric properties and fail to capture tropospheric signals over larger regions. Here we propose and test a novel power law correction method that accounts for spatial variability in atmospheric properties and can be applied to interferograms containing topographically correlated deformation. The power law model has its reference fixed at the relative top of the troposphere and describes, through a power law relationship, how the phase delay varies with altitude. We find the power law model reduces tropospheric signals both locally (on average by ∼0.45 cm for each kilometer of elevation in Mexico) and the long‐wavelength components, leading to an improved fit to independent Global Navigation Satellite Systems data. The power law model can be applied in presence of deformation, over a range of different time periods and in different atmospheric conditions, and thus permits the detection of smaller‐magnitude crustal deformation signals with InSAR. Key Points Topography‐correlated SAR delays describable by a power law and reference height New correction method for InSAR allows for spatial variations in the troposphere Spatial band filtering can be used to separate tectonic signals from troposphere