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Remote Sens. 2017, 9(8), 854; https://doi.org/10.3390/rs9080854

Technical Evaluation of Sentinel-1 IW Mode Cross-Pol Radar Backscattering from the Ocean Surface in Moderate Wind Condition

1
Shanghai Key Laboratory of Intelligent Sensing and Recognition, Shanghai Jiao Tong University, Shanghai 200240, China
2
Global Science and Technology, National Oceanic and Atmospheric Administration (NOAA)/NOAA Satellite and Information Service, College Park, MD 20740, USA
*
Author to whom correspondence should be addressed.
Academic Editors: Xiaofeng Yang, Ferdinando Nunziata and Alexis Mouche
Received: 30 June 2017 / Revised: 5 August 2017 / Accepted: 16 August 2017 / Published: 17 August 2017
(This article belongs to the Special Issue Ocean Remote Sensing with Synthetic Aperture Radar)
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Abstract

The Sentinel-1 synthetic aperture radar (SAR) allows sufficient resources for cross-pol wind speed retrievals over the ocean. In this paper, we present technical evaluation on wind retrieval from both Sentinel-1A and Sentinel-1B IW cross-pol images. Algorithms are based on the existing theoretical and empirical ones derived from the RADARSAT-2 cross-pol data. First, to better understand the Sentinel-1 observed normalized radar cross section (NRCS) values under various environmental conditions, we constructed a dataset that integrates SAR images with wind field information from scatterometer measurements. There are 11,883 matchup data in the experimental dataset. We then calculated the systemic noise floor of Sentinel-1 IW mode, and presented its unique noise characteristics among different sub-bands. Based on the calculated NESZ measurements, the noise is removed for all matchup data. Empirical relationships among the noise free NRCS σ VH 0 , wind speed, wind direction, and radar incidence angle are analyzed for each sub-band, and a piecewise model is proposed. We showed that a larger correlation coefficient, r, is achieved by including both wind direction and incidence terms in the model. Validation against scatterometer measurements showed the suitability of the proposed model. View Full-Text
Keywords: cross-pol; Sentinel-1; radar backscattering; wind retrieval cross-pol; Sentinel-1; radar backscattering; wind retrieval
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
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Huang, L.; Liu, B.; Li, X.; Zhang, Z.; Yu, W. Technical Evaluation of Sentinel-1 IW Mode Cross-Pol Radar Backscattering from the Ocean Surface in Moderate Wind Condition. Remote Sens. 2017, 9, 854.

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