Submesoscale oceanic eddy detection in SAR images using context and edge association network

Abstract

Oceanic eddies have a non-negligible impact on ocean energy transfer, nutrient distribution, and biological migration in global oceans. The fine detection of oceanic eddies is significant for the development of marine science. Remarkable achievements of eddy recognition were achieved by mining the satellite altimeter data and its derived data. However, due to the limited spatial resolution of the altimeters, it is difficult to detect the submesoscale oceanic eddies with radial dimensions less than 10 km. Different from the previous works, the context and edge association network (CEA-Net) is proposed to identify submesoscale oceanic eddies with high spatial resolution Sentinel-1 data. The edge information fusion module (EIFM) is designed to associate the context and edge feature more accurately and efficiently. Furthermore, a multi-scale eddy detection strategy is proposed and applied to Sentinel-1 interferometric wide swath data to solve the scale problem of oceanic eddy detection. Specifically, a manually interpreted dataset, SAR-Eddy 2019, was constructed to address the dilemma of insufficient datasets for submesoscale oceanic eddy detection. The experimental results demonstrate that CEA-Net can outperform other mainstream models with the highest mAP reaching 85.47% with SAR-Eddy 2019 dataset. The CEA-Net proposed in this research provides important significance for the study of submesoscale oceanic eddies.

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

“…Although deep learning methods have been applied in submesoscale eddy detection from satellite images [15,16,24], there are not enough Sentinel-1 SAR images containing submesoscale eddies to provide training sets. As a result, in the previous, similar studies, eddy factors have tended to be (successfully) detected based on visual identification of surface signatures [32,36,50,59,67].…”

“…Japanese coastal regions, with their numerous capes, turns and islands, are enveloped in wind-driven circulation [9,10] and multiscale processes [11,12]. Submesoscale eddies near the coast have been studied in different regions based on multi-source data [13][14][15][16] and numerical simulation [17,18]. However, the observation of submesoscale eddies along the Japanese coast is limited and lacks systematic analysis.…”

Estimating daily semantic segmentation maps of classified ocean eddies using sea level anomaly data from along-track altimetry

“…A recent approach for our analysis involves the use of CNNs, which have already been used to detect eddies using two-dimensional SLA or sea surface height (SSH) (Lguensat et al, 2018 ; Santana et al, 2020 ), sea surface temperature (SST) (Moschos et al, 2020 , 2022b ), both (Zhao et al, 2023 ), or other grid map observations (Xia et al, 2022 ). In most cases, such as in the study of Lguensat et al ( 2018 ), a special CNN, known as U-Net, has been used, which is a state-of-the-art method for semantic segmentation of two-dimensional data has been used.…”

“…In radar altimetry, sea surface heights are measured that contain features (highs or lows) of an eddy within the satellite footprint. The current research on eddy detection infers results either from gridded sea level anomaly (SLA) maps that are processed from multiple radar altimetry missions (Lguensat et al, 2018 ), from sea surface temperature (SST) grid maps (Moschos et al, 2020 ), from both (Zhao et al, 2023 ), or other grid map observations (Xia et al, 2022 ). Along-track (AT) altimetry data capture the instant sea-level heights at the time of measurement.…”

Variations and Depth of Formation of Submesoscale Eddy Structures in Satellite Ocean Color Data in the Southwestern Region of the Peter the Great Bay

“…Traditionally, satellite radar data have been used to study marine eddy structures [11][12][13], even in the presence of clouds. Especially useful for detecting submesoscale eddies are synthetic aperture radar (SAR) data [14,15]. Additionally, the use of satellite data in visible and infrared (IR) spectral bands significantly enhances the potential for studying submesoscale eddies [16,17].…”