Physical and Biological Satellite Observations of the Northwest African Upwelling: Spatial Extent and Dynamics

2021

Physics of Fluids

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Automatic identification and tracking of mesoscale eddies are crucial in large oceanic observational and numerical model data. This work proposes a fully automated method that identifies and tracks from a single Lagrangian advection, all mesoscale eddies, without prior knowledge of their lifespans. The eddies' detection and tracking use a hybrid method based on geometrical properties of the evolving velocity along Lagrangian trajectories and a grid density-based clustering algorithm. The high eddies' monitoring capacity of the proposed method is demonstrated by automatically identifying and tracking these structures from two different datasets: satellite-derived surface geostrophic velocity fields and a two-dimensional fluid simulation. The proposed approach gives complete dynamical features and evolution of the detected mesoscale eddies by identifying their genesis event, monitoring their coherent core, and describing their splitting and vanishing image.

Section: B Application To Satellite Geostrophic Currentsmentioning

confidence: 99%

A hybrid identification and tracking of Lagrangian mesoscale eddies

2021

Physics of Fluids

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“…In a related work, El Abidi and Minaoui [13] and El Aouni et al [14] proposed different methods to identify the upwelling along the Atlantic coast of Morocco based on the biological observation. El Aouni et al [1] and El Abidi et al [15] developed different methodologies to delineate and extract the upwelling region using the satellite observation. In fact, the method proposed in [1] was used to study the upwelling physical and biological variabilities of the northwest African region.…”

Section: In the Open Ocean)mentioning

confidence: 99%

“…El Aouni et al [1] and El Abidi et al [15] developed different methodologies to delineate and extract the upwelling region using the satellite observation. In fact, the method proposed in [1] was used to study the upwelling physical and biological variabilities of the northwest African region.…”

Section: In the Open Ocean)mentioning

confidence: 99%

“…It is characterized by the presence of the coastal upwelling phenomenon almost all year round. The hydrodynamical process of the upwelling along this region is mostly forced by the trade winds that cause cold, nutrient-rich intermediate waters to surface at the epipelagic level [1]. As a result, a variable cold and nutrient-rich current operates the coast from North to South.…”

Section: Introductionmentioning

confidence: 99%

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An Efficient Detection of Moroccan Coastal Upwelling Based on Fusion of Chlorophyll-a and Sea Surface Temperature Images With a New Validation Index

Abidi

Minaoui

IEEE Geosci. Remote Sensing Lett.

et al. 2021

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This research deals with the problem of identifying and extracting effectively the main Moroccan upwelling front. The proposed methodology, based on the image-fusion concept, comes to benefit from the information available in both sea-surface temperature (SST) and chlorophyll-a satellite images. Moreover, a new validation index is proposed by computing a simple gradient along the extracted upwelling limit. The developed procedure is applied over a database of 366 SST and 366 chlorophyll-a images from 2007 to 2014, covering the Moroccan Atlantic coast. The final results are validated qualitatively by an oceanographer and quantitatively by our innovative index. The findings of validation demonstrate the performance of our fusion approach.

“…T HE Atlantic coastline of north Africa is characterized by the presence of the upwelling phenomenon almost all around the year. This phenomenon can be identified by seasonally variable cold and nutrient-rich water [1]. Thus, the automatic identification and detection of this phenomenon is of fundamental importance in the study of productivity enhancement [2], [3] and associated fish management [4].…”

Section: Introductionmentioning

confidence: 99%

Robust Detection of the North-West African Upwelling From SST Images

IEEE Geosci. Remote Sensing Lett.

Daoudi²,

Minaoui³

et al. 2021

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Analysis and study of coastal upwelling using sea surface temperature (SST) satellite images is a common procedure because of its coast effectiveness (economic, time, frequency, and manpower). Developing on the Ekman theory, we propose a robust method to identify the upwelling regions along the northwest African margin. The proposed method comes to overcome the issues encountered in a recent method devoted for the same purpose and for the same upwelling system. Afterward, we show how our method can serve as a framework to study and monitor the spatio-temporal variability of the upwelling phenomenon in the studied region.