Numerical simulation of the effect of the sea surface current gradient on the SAR radial velocity

Elyouncha, Anis ORCID: https://orcid.org/0000-0002-3586-7988; Martin, Adrien C. H.; Gommenginger, Christine ORCID: https://orcid.org/0000-0002-6941-1671. 2025 Numerical simulation of the effect of the sea surface current gradient on the SAR radial velocity. Remote Sensing Letters, 16 (9). 970-980. 10.1080/2150704X.2025.2521066

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Text © 2025 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The terms on which this article has been published allow the posting of the Accepted Manuscript in a repository by the author(s) or with their consent. Numerical simulation of the effect of the sea surface current gradient on the SAR radial velocity.pdf - Published Version Available under License Creative Commons Attribution 4.0. Download (1MB) | Preview

Abstract/Summary

Wave-current interactions are typically neglected when retrieving radial velocities from synthetic aperture radar (SAR) data. In this study, the impact of spatially varying currents on wind waves and swell, and on SAR-derived radial velocity, is simulated using the SWAN wave model and two semi-empirical Doppler models. Simulations were conducted for two wind speeds (5 and 10 m s −1) along with two current profiles (convergent and divergent). The results indicate that the magnitude of variation in wave-induced Doppler velocity (Δ⁢�D) increases with the strength of the current gradient. This is primarily attributed to the increase (decrease) in significant wave height (�s) and the decrease (increase) in peak period (�p) under convergent (divergent) currents. Additionally, convergent currents lead to larger variations in Δ⁢�D. The impact of wind speed is relatively minor. When considering only the modulation of �s, Δ⁢�D exceeds 0.1 m s −1 only in cases where the current front is 1 km wide, and this threshold is surpassed only locally. However, when both �s and �p modulations are taken into account, Δ⁢�D exceeds 0.1 m s −1 over approximately 10 km beyond the front. In contrast, the swell-current interaction under the conditions simulated in this study results in a negligible Δ⁢�D.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	10.1080/2150704X.2025.2521066
ISSN:	2150-704X
Additional Keywords:	Ocean surface current, wave-current interaction, SAR, wave Doppler
NORA Subject Terms:	Marine Sciences
Date made live:	28 Jul 2025 12:54 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/539952

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