Performance Analysis of Ocean Eddy Detection and Identification by L-Band Compact Polarimetric Synthetic Aperture Radar

Shu, Sijing; Yang, Ji; Yang, Chunling; Hu, Hsiao-Yun; Jing, Wenlong; Hu, Yiqiang; Li, Yong

doi:10.3390/rs13234905

Cited by 4 publications

(4 citation statements)

References 47 publications

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“…Fig. 14 demonstrates two examples of eddies on ALOS PALSAR VV-polarized backscattering coefficient images [177]. Considering the importance of near-surface wind speed for eddies detection in SAR images, wind data from a numerical model was also utilized to enhance the results.…”

Section: K Eddiesmentioning

confidence: 99%

Synthetic Aperture Radar (SAR) for Ocean: A Review

Asiyabi,

Ghorbanian,

Tameh

et al. 2023

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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Oceans cover approximately 71% of the Earth's surface and provide numerous services to the environment and humans. Precise, real-time, and large-scale monitoring of the oceanographic parameters is essential for ocean conservation and understanding the interactions between oceans and the atmosphere. In this regard, Synthetic Aperture Radar (SAR) systems, with unique capabilities (e.g., day-night and almost allweather data acquisition), provide valuable datasets for ocean studies. Many studies have exploited the applications of SAR imagery for oceans and have proposed numerous methods to study oceanographic parameters. In this study, a brief introduction to SAR and the interaction between microwave signals and the ocean surface are initially provided. Then, the important spaceborne and airborne SAR systems for oceanographic applications are summarized. Subsequently, 12 different applications of SAR systems in the ocean are comprehensively discussed, and the advantages and disadvantages of SAR systems for ocean studies are extensively explored. Finally, the research trend on SAR applications in the ocean is provided by analyzing all the relevant papers published between 1973 and the end of December 2022, and the existing challenges are discussed for future studies.

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Section: K Eddiesmentioning

confidence: 99%

Synthetic Aperture Radar (SAR) for Ocean: A Review

Asiyabi,

Ghorbanian,

Tameh

et al. 2023

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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“…SAR is, therefore, a good instrument to detect the detailed structures of mesoscale/submesoscale eddies and filaments [25][26][27][28][29], thereby enabling the study of the statistical characteristics and generation mechanisms of submesoscale eddies [30,31]. There are four general mechanisms responsible for eddy manifestations on SAR images: (i) spatial heterogeneity of atmospheric stability due to wind stress over ocean fronts [32], (ii) surface films associated with eddy-induced surface convergence [33,34], (iii) roughness changes caused by wave-current interactions [35], and (iv) spatial redistribution of eddies traced by drifting ice [36]. In SAR images, eddies look like "black" areas at low to moderate wind speeds (~0.2-5.6 m/s), but appear "white" at higher wind speeds (6-12.5 m/s) [32,37].…”

Section: Introductionmentioning

confidence: 99%

The Characteristics of Submesoscale Eddies near the Coastal Regions of Eastern Japan: Insights from Sentinel-1 Imagery

Li,

He,

Wen

et al. 2024

JMSE

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A long-term time series of 319 Sentinel-1 SAR Imagery with Interferometric Wide Swath (IW) mode was used to study the characteristics of submesoscale eddies over Japanese coastal regions from 2015 to 2021, including spatiotemporal eddy properties and possible mechanisms of their formation. The results showed that around 98% of the 1499 eddies identified from the SAR snapshots were submesoscale eddies (horizontal scales of O1–20 km) with a ratio of around 78% cyclones to around 22% anticyclones. Around 8% of the submesoscale eddies were found in these SAR images in winter since the submesoscale current-induced signals are masked by the stronger wind speed, compared with other seasons. Typical features of submesoscale eddies are summarized, providing a preliminary qualitative analysis of potential generation mechanisms specific to the eddy characteristics in this region. This study suggests that Sentinel-1 images are capable of providing insights into the observed submesoscale eddies near the coastal regions of eastern Japan, thereby contributing to the improved understanding of the generation of submesoscale eddies.

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“…The high spatiotemporal variability of submesoscale/mesoscale gyres/eddies in seas and oceans makes satellite imagery an appropriate tool for observing the size and distribution of such coherent circulations [6,[14][15][16]. In particular, Synthetic Aperture Radar (SAR) imagery is often used to detect mesoscale/submesoscale circulation patterns (e.g., [17][18][19][20][21]).…”

Section: Introductionmentioning

confidence: 99%

“…The bright lines outline the shape of submesoscale/mesoscale eddies. Eddies manifested by this mechanism are referred to as 'white' eddies [15,17,34]. Existing algorithms for detecting eddies in SAR imagery are generally designed to identify 'white' or 'black' eddies.…”

Section: Introductionmentioning

confidence: 99%

Monitoring Mesoscale to Submesoscale Processes in Large Lakes with Sentinel-1 SAR Imagery: The Case of Lake Geneva

et al. 2022

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As in oceans, large-scale coherent circulations such as gyres and eddies are ubiquitous features in large lakes that are subject to the Coriolis force. They play a crucial role in the horizontal and vertical distribution of biological, chemical and physical parameters that can affect water quality. In order to make coherent circulation patterns evident, representative field measurements of near-surface currents have to be taken. This, unfortunately, is difficult due to the high spatial and temporal variability of gyres/eddies. As a result, few complete field observations of coherent circulation in oceans/lakes have been reported. With the advent of high-resolution satellite imagery, the potential to unravel and improve the understanding of mesoscale and submesoscale processes has substantially increased. Features in the satellite images, however, must be verified by field measurements and numerical simulations. In the present study, Sentinel-1 SAR satellite imagery was used to detect gyres/eddies in a large lake (Lake Geneva). Comparing SAR images with realistic high-resolution numerical model results and in situ observations allowed for identification of distinct signatures of mesoscale gyres, which can be revealed through submesoscale current patterns. Under low wind conditions, cyclonic gyres manifest themselves in SAR images either through biogenic slicks that are entrained in submesoscale and mesoscale currents, or by pelagic upwelling that appears as smooth, dark elliptical areas in their centers. This unique combination of simultaneous SAR imagery, three-dimensional numerical simulations and field observations confirmed that SAR imagery can provide valuable insights into the spatial scales of thus far unresolved mesoscale and submesoscale processes in a lake. Understanding these processes is required for developing effective lake management concepts.

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Performance Analysis of Ocean Eddy Detection and Identification by L-Band Compact Polarimetric Synthetic Aperture Radar

Cited by 4 publications

References 47 publications

Synthetic Aperture Radar (SAR) for Ocean: A Review

Synthetic Aperture Radar (SAR) for Ocean: A Review

The Characteristics of Submesoscale Eddies near the Coastal Regions of Eastern Japan: Insights from Sentinel-1 Imagery

Monitoring Mesoscale to Submesoscale Processes in Large Lakes with Sentinel-1 SAR Imagery: The Case of Lake Geneva

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