Variability of Dissolved Oxygen in the Bottom Layer of the Southern Senegalese Shelf - ANR - Agence nationale de la recherche Accéder directement au contenu
Article Dans Une Revue Journal of Geophysical Research. Oceans Année : 2021

Variability of Dissolved Oxygen in the Bottom Layer of the Southern Senegalese Shelf

Résumé

The observation station “Melax” was deployed in 2015 on the wide and shallow south Senegalese shelf to study the ocean dynamics, air-sea interactions, and dissolved oxygen (DO) cycle. Data from February 2015 to August 2016 were used to study the main physical processes affecting the variability of DO in the bottom layer (∼30 m depth) on time scales ranging from tidal to seasonal. Between November and May, wind-driven upwelling provides phytoplankton enrichment of the surface layers and brings cold, salty, and depleted DO on the shelf. Water properties at Melax vary depending on the source waters located at the shelf edge. The DO concentration changes between the shelf edge and Melax are broadly consistent with the inferred respiration rates estimated in previous studies. In contrast, the monsoon season (July–October) is characterized by weak westerly winds and northward currents. Bottom waters are warmer, fresher, and more oxygenated. The slower circulation in this period allows a stronger decoupling between the water properties of the waters observed at Melax and those of the source waters. Stratification strengthening near the bottom layer inhibits vertical mixing and induces strong high-frequency variability in properties caused by internal tide-generated waves. Intense upwelling events can deepen the mixed layer and intermittently transform the bottom layer waters (locally or remotely). Relaxation events associated with current reversals significantly modify their properties. Coastal trapped waves constitute a distant forcing that can act year-round, impacting both shelf waters and source regions.
Fichier principal
Vignette du fichier
JGR Oceans - 2021 - Tall - Variability of Dissolved Oxygen in the Bottom Layer of the Southern Senegalese Shelf.pdf (3.78 Mo) Télécharger le fichier
Origine : Fichiers éditeurs autorisés sur une archive ouverte

Dates et versions

hal-03319671 , version 1 (16-08-2022)

Licence

Copyright (Tous droits réservés)

Identifiants

Citer

Abdoul Wahab Tall, Éric Machu, Vincent Echevin, Xavier Capet, Alice Pietri, et al.. Variability of Dissolved Oxygen in the Bottom Layer of the Southern Senegalese Shelf. Journal of Geophysical Research. Oceans, 2021, 126 (5), pp.e2020JC016854. ⟨10.1029/2020JC016854⟩. ⟨hal-03319671⟩
95 Consultations
73 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More