Comprehensive Assessment of Ocean Surface Current Retrievals Using SAR Doppler Shift and Drifting Buoy Observations
Ocean surface radial current velocities can be derived from synthetic aperture radar (SAR) Doppler shift observations using the Doppler centroid technique and a recently developed Doppler velocity model. However, comprehensive evaluations of the accuracy and reliability of these retrievals remain li...
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MDPI AG
2025-06-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/17/12/2007 |
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| author | Shengren Fan Biao Zhang Vladimir Kudryavtsev |
| author_facet | Shengren Fan Biao Zhang Vladimir Kudryavtsev |
| author_sort | Shengren Fan |
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| description | Ocean surface radial current velocities can be derived from synthetic aperture radar (SAR) Doppler shift observations using the Doppler centroid technique and a recently developed Doppler velocity model. However, comprehensive evaluations of the accuracy and reliability of these retrievals remain limited. To address this gap, we analyzed 6341 Sentinel-1 SAR scenes acquired over the South China Sea (SCS) between December 2017 and October 2023, in conjunction with drifting buoy observations, to systematically validate the retrieved radial current velocities. A linear fitting method and the dual co-polarization Doppler velocity (DPDop) model were applied to correct for the influence of non-geophysical factors and sea state effects. The validation against the drifter data yielded a bias of 0.01 m/s, a root mean square error (RMSE) of 0.18 m/s, and a mean absolute error (MAE) of 0.16 m/s. Further comparisons with the Surface and Merged Ocean Currents (SMOC) dataset revealed bias, RMSE, and MAE values of 0.07 m/s, 0.14 m/s, and 0.12 m/s in the Beibu Gulf, and −0.06 m/s, 0.23 m/s, and 0.19 m/s in the Kuroshio intrusion area. These results demonstrate that SAR Doppler measurements have a strong potential to complement existing ocean observations in the SCS by providing high-resolution (1 km) ocean surface current maps. |
| format | Article |
| id | doaj-art-acd65feb8137498dab8984a6c50eeb81 |
| institution | Kabale University |
| issn | 2072-4292 |
| language | English |
| publishDate | 2025-06-01 |
| publisher | MDPI AG |
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| series | Remote Sensing |
| spelling | doaj-art-acd65feb8137498dab8984a6c50eeb812025-08-20T03:29:35ZengMDPI AGRemote Sensing2072-42922025-06-011712200710.3390/rs17122007Comprehensive Assessment of Ocean Surface Current Retrievals Using SAR Doppler Shift and Drifting Buoy ObservationsShengren Fan0Biao Zhang1Vladimir Kudryavtsev2Satellite Oceanography Laboratory, Russian State Hydrometeorological University, St. Petersburg 195196, RussiaState Key Laboratory of Climate System Prediction and Risk Management, Nanjing University of Information Science and Technology, Nanjing 210044, ChinaSatellite Oceanography Laboratory, Russian State Hydrometeorological University, St. Petersburg 195196, RussiaOcean surface radial current velocities can be derived from synthetic aperture radar (SAR) Doppler shift observations using the Doppler centroid technique and a recently developed Doppler velocity model. However, comprehensive evaluations of the accuracy and reliability of these retrievals remain limited. To address this gap, we analyzed 6341 Sentinel-1 SAR scenes acquired over the South China Sea (SCS) between December 2017 and October 2023, in conjunction with drifting buoy observations, to systematically validate the retrieved radial current velocities. A linear fitting method and the dual co-polarization Doppler velocity (DPDop) model were applied to correct for the influence of non-geophysical factors and sea state effects. The validation against the drifter data yielded a bias of 0.01 m/s, a root mean square error (RMSE) of 0.18 m/s, and a mean absolute error (MAE) of 0.16 m/s. Further comparisons with the Surface and Merged Ocean Currents (SMOC) dataset revealed bias, RMSE, and MAE values of 0.07 m/s, 0.14 m/s, and 0.12 m/s in the Beibu Gulf, and −0.06 m/s, 0.23 m/s, and 0.19 m/s in the Kuroshio intrusion area. These results demonstrate that SAR Doppler measurements have a strong potential to complement existing ocean observations in the SCS by providing high-resolution (1 km) ocean surface current maps.https://www.mdpi.com/2072-4292/17/12/2007synthetic aperture radar (SAR)doppler shiftDPDop modelsea statesocean surface current |
| spellingShingle | Shengren Fan Biao Zhang Vladimir Kudryavtsev Comprehensive Assessment of Ocean Surface Current Retrievals Using SAR Doppler Shift and Drifting Buoy Observations Remote Sensing synthetic aperture radar (SAR) doppler shift DPDop model sea states ocean surface current |
| title | Comprehensive Assessment of Ocean Surface Current Retrievals Using SAR Doppler Shift and Drifting Buoy Observations |
| title_full | Comprehensive Assessment of Ocean Surface Current Retrievals Using SAR Doppler Shift and Drifting Buoy Observations |
| title_fullStr | Comprehensive Assessment of Ocean Surface Current Retrievals Using SAR Doppler Shift and Drifting Buoy Observations |
| title_full_unstemmed | Comprehensive Assessment of Ocean Surface Current Retrievals Using SAR Doppler Shift and Drifting Buoy Observations |
| title_short | Comprehensive Assessment of Ocean Surface Current Retrievals Using SAR Doppler Shift and Drifting Buoy Observations |
| title_sort | comprehensive assessment of ocean surface current retrievals using sar doppler shift and drifting buoy observations |
| topic | synthetic aperture radar (SAR) doppler shift DPDop model sea states ocean surface current |
| url | https://www.mdpi.com/2072-4292/17/12/2007 |
| work_keys_str_mv | AT shengrenfan comprehensiveassessmentofoceansurfacecurrentretrievalsusingsardopplershiftanddriftingbuoyobservations AT biaozhang comprehensiveassessmentofoceansurfacecurrentretrievalsusingsardopplershiftanddriftingbuoyobservations AT vladimirkudryavtsev comprehensiveassessmentofoceansurfacecurrentretrievalsusingsardopplershiftanddriftingbuoyobservations |