Quality Assessment of Surface Current Fields From TerraSAR-X and TanDEM-X Along-Track Interferometry and Doppler Centroid Analysis

Romeiser, Roland; Runge, Harmut; Suchandr, Steffan; Kahle, Ralph; Rossi, Cristian; Bell, Paul S.. 2014 Quality Assessment of Surface Current Fields From TerraSAR-X and TanDEM-X Along-Track Interferometry and Doppler Centroid Analysis. IEEE Transactions on Geoscience and Remote Sensing, 52 (5). 2759-2772. 10.1109/TGRS.2013.2265659

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All existing examples of current measurements by spaceborne synthetic aperture radar (SAR) along-track (AT) interferometry (ATI) have suffered from short baselines and corresponding low sensitivities. Theoretically, the best data quality at X-band is expected at effective baselines on the order of 30 m, i.e., 30 times as long as the baselines of the divided-antenna modes of TerraSAR-X. In early 2012, we had a first opportunity to obtain data at near-optimum baselines from the TanDEM-X satellite formation. In this paper, we analyze two TanDEM-X interferograms acquired over the Pentland Firth (Scotland) with effective AT baselines of 25 and 40 m. For comparison, we consider a TerraSAR-X dual-receive-antenna (DRA)-mode interferogram with an effective baseline of 1.15 m, as well as velocity fields obtained by Doppler centroid analysis (DCA) of single-antenna data from the same three scenes. We show that currents derived from the TanDEM-X interferograms have a residual noise level of 0.1 m/s at an effective resolution of about 33 m $times$ 33 m, while DRA-mode data must be averaged over 1000 m $times$ 1000 m to reach the same level of accuracy. A comparison with reference currents from a 1-km resolution numerical tide computation system shows good agreement in all three cases. The DCA-based currents are found to be less accurate than the ATI-based ones but close to short-baseline ATI results in quality. We conclude that DCA is a considerable alternative to divided-antenna mode ATI, while our TanDEM-X results demonstrate the true potential of the ATI technique at near-optimum baselines.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1109/TGRS.2013.2265659
ISSN: 0196-2892
Additional Keywords: Synthetic aperture radar, Interferometry, Radar velocity measurement, Remote sensing
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Date made live: 16 Jul 2013 15:15 +0 (UTC)

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