Abstract
Radar altimeters using interferometric synthetic aperture radar (InSAR) techniques at near-nadir angles have been proposed to measure elevations of the ocean and the inland water with wide swath and high spatial resolution. The Ku-band Interferometric Imaging Radar Altimeter (InIRA) on the Tiangong-2 space laboratory, which was launched on 15 September 2016, is the first spaceborne instrument of such kind. Another similar instrument is the forthcoming Ka-band Radar Interferometer (KaRIn) of the Surface Water and Ocean Topography (SWOT) mission. In the interferometric processings, which have to be done to derive the elevations with the interferometric altimeter, the phase filtering and the phase unwrapping are two key steps. There are many filtering and unwrapping methods for conventional InSAR published in literature, but very few for interferometric altimeters. In this paper, several common filtering and unwrapping methods were evaluated with real InIRA acquisitions over three different scenes, including an open ocean, a coastal area, and a land with a mountain. The phase filtering was evaluated by the pseudo-correlation coefficient, the residue number, and the Root Mean Square (RMS) of the difference between the filtered phase and the original phase. The phase unwrapping was evaluated by the statistics of the difference between the rewrapped phase and the input wrapped phase, the ε value, and the discontinuity number. The evaluation results were shown and some recommendations were made on the method selection and the parameter setting for interferometric altimeters.
Access this chapter
Tax calculation will be finalised at checkout
Purchases are for personal use only
References
Enjolras, V., Vincent, P., Souyris, J.-C., Rodriguez, E., Phalippou, L., Cazenave, A.: Performances study of interferometric radar altimeters: from the instrument to the global mission definition. Sensors. 6(3), 164–192 (2006)
Esteban-Fernandez, D., Fu, L.L., Rodriguez, E., Brown, S., Hodges, R.: Ka-band SAR interferometry studies for the SWOT mission. In: Proceedings of the IEEE IGARSS, pp. 4401–4402. IEEE, Honolulu (2010)
Moller, D., Farquharson, G., Esteban-Fernandez, D.: Assessment of near-nadir correlation characteristics over water bodies using interferometric SAR: Implications for the swot mission. In: Proceedings of the IEEE IGARSS, pp. 3219–3222. IEEE, Beijing (2016)
Kong, W., Chong, J., Tan, H.: Performance analysis of ocean surface topography altimetry by Ku-Band Near-Nadir Interferometric SAR. Remote Sens. 9(9), 933 (2017)
Ren, L., Yang, J., Zhang, Y., Zhai, W., Zheng, G., Wang, J.: Exploring for the wind speed retrieval from Interferometric Imaging Radar Altimeter. In: Proceedings of the IEEE IGARSS, pp. 4637–4640. IEEE, Beijing (2016)
Fu L., Alsdorf D., Morrow R., Rodríguez E. and Mognard N.: SWOT: The Surface Water and Ocean Topography mission: Wide-swath altimetric measurement of water elevation on Earth. Jet Propulsion Lab., NASA Technical Reports Server, Pasadena (2012)
Yang, J., Ren, L., Zheng, G.: The first quantitative ocean remote sensing by using Chinese interferometric imaging radar altimeter onboard TG-2. Acta Oceanol. Sin. 36(2), 122–123 (2017)
Bao, Q., Lin, M., Zhang, Y., Jia, Y., Lang, S.: Wind speed inversion for imaging microwave altimeter. J. Remote Sens. 21, 835–841 (2017)
Fu, L.-L., Rodriguez, E.: High-resolution measurement of ocean surface topography by Radar Interferometry for Oceanographic and Geophysical Applications. In: The State of the Planet: Frontiers and Challenges in Geophysics, 1st edn. American Geophysical Union, Washington, D. C. (2004)
Durand, M., Fu, L.L., Lettenmaier, D.P., Alsdorf, D.E., Rodriguez, E., Esteban-Fernandez, D.: The surface water and ocean topography mission: observing terrestrial surface water and oceanic submesoscale eddies. In: Proceedings of the IEEE IGARSS, pp. 766–779. IEEE, Honolulu (2010)
Li, S., Tan, H., Liu, Z., Zhou, Z., Liu, Y., Zhang, W., Liu, K., Qin, B.: Mapping high mountain lakes using space-borne near-nadir SAR observations. Remote Sens. 10(9), 1418 (2018)
Goldstein, R.M., Werner, C.L.: Radar interferogram filtering for geophysical applications. Geophys. Res. Lett. 25(21), 4035–4038 (1998)
Jin, G., Xu, Q., Zhang, H.: Synthetic Aperture Radar Interferometry, 1st edn. National Defense Industry Press, Beijing, China (2014)
Goldstein, R.M., Zebker, H.A., Werner, C.L.: Satellite radar interferometry: two-dimensional phase unwrapping. Radio Sci. 23(4), 713–720 (1988)
Ghiglia, D.C., Pritt, M.D.: Two-dimensional phase unwrapping: theory, algorithms, and software, 1st edn. Wiley, New York (1998)
Acknowledgements
Thanks to China Manned Space Engineering for providing space science and application data products. Thanks to Xiao Dong and Yunhua Zhang in the Key Laboratory of Microwave Remote Sensing, Chinese Academy of Sciences, for their discussions on the instrument design and for their help in generating the complex images.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2019 Springer Nature Singapore Pte Ltd.
About this paper
Cite this paper
Tan, H., Li, S., Liu, Z., Zhang, W., Li, L. (2019). Evaluation of Several Filtering and Unwrapping Methods for the Interferometric Imaging Radar Altimeter. In: Gu, Y., Gao, M., Zhao, G. (eds) Proceedings of the Tiangong-2 Remote Sensing Application Conference. Lecture Notes in Electrical Engineering, vol 541. Springer, Singapore. https://doi.org/10.1007/978-981-13-3501-3_9
Download citation
DOI: https://doi.org/10.1007/978-981-13-3501-3_9
Published:
Publisher Name: Springer, Singapore
Print ISBN: 978-981-13-3500-6
Online ISBN: 978-981-13-3501-3
eBook Packages: EngineeringEngineering (R0)