Mitigation of Tropospheric Delay in SAR and InSAR Using NWP Data: Its Validation and Application Examples

The neutral atmospheric delay has a great impact on synthetic aperture radar (SAR) absolute ranging and on differential interferometry. In this paper, we demonstrate its effective mitigation by means of the direction integration method using two products from the European Centre for Medium-Range Wea...

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Bibliographic Details
Published in:Remote sensing (Basel, Switzerland) Switzerland), 2018-10, Vol.10 (10), p.1515
Main Authors: Cong, Xiaoying, Balss, Ulrich, Rodriguez Gonzalez, Fernando, Eineder, Michael
Format: Article
Language:English
Subjects:
atmospheric propagation delay
numerical weather prediction
persistent scatterer interferometry
SAR
SAR interferometry
slant path delay
stratified atmospheric delay
zenith path delay
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Summary:The neutral atmospheric delay has a great impact on synthetic aperture radar (SAR) absolute ranging and on differential interferometry. In this paper, we demonstrate its effective mitigation by means of the direction integration method using two products from the European Centre for Medium-Range Weather Forecast: ERA-Interim and operational data. Firstly, we shortly review the modeling of the neutral atmospheric delay for the direct integration method, focusing on the different refractivity models and constant coefficients available. Secondly, a thorough validation of the method is performed using two approaches. In the first approach, numerical weather prediction (NWP) derived zenith path delay (ZPD) is validated against ZPD from permanent GNSS (global navigation satellite system) stations on a global scale, demonstrating a mean accuracy of 14.5 mm for ERA-Interim. Local analysis shows a 1 mm improvement using operational data. In the second approach, NWP derived slant path delay (SPD) is validated against SAR SPD measured on corner reflectors in more than 300 TerraSAR-X High Resolution SpotLight acquisitions, demonstrating an accuracy in the centimeter range for both ERA-Interim and operational data. Finally, the application of this accurate delay estimate for the mitigation of the impact of the neutral atmosphere on SAR absolute ranging and on differential interferometry, both for individual interferograms and multi-temporal processing, is demonstrated.
ISSN:2072-4292
2072-4292
DOI:10.3390/rs10101515