Abstract
The complexity of the atmosphere renders the modelling of the atmospheric delay in multi temporal InSAR difficult. This limits the potential of achieving millimetre accuracy of InSAR-derived deformation measurements. In this paper we review advances in tropospheric delay modelling in InSAR, tropospheric correction methods and integration of the correction methods within existing multi temporal algorithms. Furthermore, we investigate ingestion of the correction techniques by different InSAR applications, accuracy performance metrics and uncertainties of InSAR derived measurements attributed to tropospheric delay. Spatiotemporal modelling of atmospheric delay has evolved and can now be regarded as a spatially correlated turbulent delay with varying degree of anisotropy random in time and topographically correlated seasonal stratified delay. Tropospheric corrections methods performance is restricted to a case by case basis and ingestion of these methods by different applications remains limited due to lack of their integration into existing algorithms. Accuracy and uncertainty assessments remain challenging with most studies adopting simple statistical metrics. While advances have been made in tropospheric modelling, challenges remain for the calibration of atmospheric delay due to lack of data or limited resolution and fusion of multiple techniques for optimal performance.
Highlights
Interferometric Synthetic Aperture Radar (InSAR) has proven to be a powerful geodetic space technique allowing measurements and observation over large area with a sub-centimetre accuracy in applications related to anthropogenic activities (Amelung et al 1999; Juncu et al 2018; Xu et al 2017), landslides (Bianchini et al 2013; Ciampalini et al 2015; Rott and Nagler 2006) and geophysical processes (Béjar-Pizarro et al 2013; Biggs et al 2007; Hooper et al 2004)
While success has been achieved in modelling tropospheric delay characteristics in InSAR, their mitigation remains a major challenge due to the complexity of the atmosphere, the lack of external data or limited availability of data needed for the calibration of tropospheric delay
All components of the tropospheric delay need to be accounted for, as ignoring the hydrostatic delay may lead to unreliable results for large-scale processing that stretches through different climatic zones
Summary
Interferometric Synthetic Aperture Radar (InSAR) has proven to be a powerful geodetic space technique allowing measurements and observation over large area with a sub-centimetre accuracy in applications related to anthropogenic activities (Amelung et al 1999; Juncu et al 2018; Xu et al 2017), landslides (Bianchini et al 2013; Ciampalini et al 2015; Rott and Nagler 2006) and geophysical processes (Béjar-Pizarro et al 2013; Biggs et al 2007; Hooper et al 2004). This success was augmented by improved data availability with missions like Sentinel-1 from the European Space Agency (ESA) granting free access to data. Rémy et al (2015) reported no deformation had occurred at Llaima volcano as earlier reported by Bathke (2011), as any deformation less than ± 7 cm could not be detectable as this was
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