Synergistic Utilization of Spaceborne SAR Observations for Monitoring the Baltic Sea Flow Through the Danish Straits

Abstract Synthetic aperture radar (SAR) has emerged as a key instrument in oceanography due to its high spatial resolution and sensitivity to ocean surface dynamics. The main limitation of a single spaceborne SAR is the long repeat cycle (e.g., 12 days for Sentinel‐1), which hinders its capability t...

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Main Authors: Anis Elyouncha, Göran Broström, Harald Johnsen
Format: Article
Language:English
Published: American Geophysical Union (AGU) 2024-10-01
Series:Earth and Space Science
Subjects:
Online Access:https://doi.org/10.1029/2024EA003794
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author Anis Elyouncha
Göran Broström
Harald Johnsen
author_facet Anis Elyouncha
Göran Broström
Harald Johnsen
author_sort Anis Elyouncha
collection DOAJ
description Abstract Synthetic aperture radar (SAR) has emerged as a key instrument in oceanography due to its high spatial resolution and sensitivity to ocean surface dynamics. The main limitation of a single spaceborne SAR is the long repeat cycle (e.g., 12 days for Sentinel‐1), which hinders its capability to monitor the temporal evolution of oceanic processes. The principal objective of this study is to demonstrate the potential of spaceborne SAR to monitor the temporal variation of ocean surface circulation. This is assessed using the Baltic Sea flow through the Danish strait Fehmarn Belt as a case study. In order to overcome the temporal sampling limitation, data from three satellites are combined, namely Sentinel‐1A, Sentinel‐1B and TanDEM‐X. The average revisit time achieved by combining the three satellites is 1.2 days. Two months of opportunistic SAR data (June and July 2020) covering the Fehmarn Belt are used. The radial surface current derived from SAR is compared to ocean model and in situ data. It is shown that the dominant processes that govern the circulation in the Fehmarn Belt exhibit time scales larger than 2 days. Subsequently, it is demonstrated that SAR effectively captures the synoptic‐scale features (time scales larger than 2 days) of the Baltic Sea circulation, thereby enabling monitoring the temporal variations of flow dynamics. Comparison of the SAR‐derived radial surface current against in situ measurements yields comparable bias (≤0.08 m/s) and correlation coefficient (R ≈ 0.75) but lower standard deviations and rms errors (0.15 m/s) than those exhibited by the ocean model (0.31 m/s).
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spelling doaj-art-6779fa94c55d439dad0e539ca97520e42025-08-20T02:12:14ZengAmerican Geophysical Union (AGU)Earth and Space Science2333-50842024-10-011110n/an/a10.1029/2024EA003794Synergistic Utilization of Spaceborne SAR Observations for Monitoring the Baltic Sea Flow Through the Danish StraitsAnis Elyouncha0Göran Broström1Harald Johnsen2University of Gothenburg Gothenburg SwedenUniversity of Gothenburg Gothenburg SwedenNorwegian Research Centre (NORCE) Tromsø NorwayAbstract Synthetic aperture radar (SAR) has emerged as a key instrument in oceanography due to its high spatial resolution and sensitivity to ocean surface dynamics. The main limitation of a single spaceborne SAR is the long repeat cycle (e.g., 12 days for Sentinel‐1), which hinders its capability to monitor the temporal evolution of oceanic processes. The principal objective of this study is to demonstrate the potential of spaceborne SAR to monitor the temporal variation of ocean surface circulation. This is assessed using the Baltic Sea flow through the Danish strait Fehmarn Belt as a case study. In order to overcome the temporal sampling limitation, data from three satellites are combined, namely Sentinel‐1A, Sentinel‐1B and TanDEM‐X. The average revisit time achieved by combining the three satellites is 1.2 days. Two months of opportunistic SAR data (June and July 2020) covering the Fehmarn Belt are used. The radial surface current derived from SAR is compared to ocean model and in situ data. It is shown that the dominant processes that govern the circulation in the Fehmarn Belt exhibit time scales larger than 2 days. Subsequently, it is demonstrated that SAR effectively captures the synoptic‐scale features (time scales larger than 2 days) of the Baltic Sea circulation, thereby enabling monitoring the temporal variations of flow dynamics. Comparison of the SAR‐derived radial surface current against in situ measurements yields comparable bias (≤0.08 m/s) and correlation coefficient (R ≈ 0.75) but lower standard deviations and rms errors (0.15 m/s) than those exhibited by the ocean model (0.31 m/s).https://doi.org/10.1029/2024EA003794ocean remote sensingocean surface currentssynthetic aperture radar
spellingShingle Anis Elyouncha
Göran Broström
Harald Johnsen
Synergistic Utilization of Spaceborne SAR Observations for Monitoring the Baltic Sea Flow Through the Danish Straits
Earth and Space Science
ocean remote sensing
ocean surface currents
synthetic aperture radar
title Synergistic Utilization of Spaceborne SAR Observations for Monitoring the Baltic Sea Flow Through the Danish Straits
title_full Synergistic Utilization of Spaceborne SAR Observations for Monitoring the Baltic Sea Flow Through the Danish Straits
title_fullStr Synergistic Utilization of Spaceborne SAR Observations for Monitoring the Baltic Sea Flow Through the Danish Straits
title_full_unstemmed Synergistic Utilization of Spaceborne SAR Observations for Monitoring the Baltic Sea Flow Through the Danish Straits
title_short Synergistic Utilization of Spaceborne SAR Observations for Monitoring the Baltic Sea Flow Through the Danish Straits
title_sort synergistic utilization of spaceborne sar observations for monitoring the baltic sea flow through the danish straits
topic ocean remote sensing
ocean surface currents
synthetic aperture radar
url https://doi.org/10.1029/2024EA003794
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AT haraldjohnsen synergisticutilizationofspacebornesarobservationsformonitoringthebalticseaflowthroughthedanishstraits