Oxygen Saturation Surrounding Deep Water Formation Events in the Labrador Sea From Argo-O-2 Data - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Global Biogeochemical Cycles Année : 2018

Oxygen Saturation Surrounding Deep Water Formation Events in the Labrador Sea From Argo-O-2 Data

Mitchell K. Wolf
  • Fonction : Auteur
Roberta C. Hamme
  • Fonction : Auteur
Denis Gilbert
Igor Yashayaev

Résumé

Deep water formation supplies oxygen-rich water to the deep sea, spreading throughout the ocean by means of the global thermohaline circulation. Models suggest that dissolved gases in newly formed deep water do not come to equilibrium with the atmosphere. However, direct measurements during wintertime convection are scarce, and the controls over the extent of these disequilibria are poorly quantified. Here we show that, when convection reached deeper than 800 m, oxygen in the Labrador Sea was consistently undersaturated at -6.1% to -7.6% at the end of convection. Deeper convection resulted in greater undersaturation, while convection ending later in the year resulted in values closer to equilibrium, from which we produce a predictive relationship. We use dissolved oxygen data from six profiling Argo floats in the Labrador Sea between 2003 and 2016, allowing direct observations of wintertime convection. Three of the six optode oxygen sensors displayed substantial average in situ drift of -3.03 mu mol O-2 kg(-1)yr(-1) (-0.94% O-2 yr(-1)), which we corrected to stable deepwater oxygen values from repeat ship surveys. Observations of low oxygen intrusions during restratification and a simple mixing calculation demonstrate that lateral processes act to lower the oxygen inventory of the central Labrador Sea. This suggests that the Labrador Sea is a net sink for atmospheric oxygen, but uncertainties in parameterizing gas exchange limit our ability to quantify the net uptake. Our results constrain the oxygen concentration of newly formed Labrador Sea Water and allow more precise estimates of oxygen utilization and nutrient regeneration in this water mass.
Fichier principal
Vignette du fichier
56829.pdf (2.55 Mo) Télécharger le fichier
Origine Fichiers éditeurs autorisés sur une archive ouverte

Dates et versions

hal-04202123 , version 1 (06-10-2023)

Licence

Copyright (Tous droits réservés)

Identifiants

Citer

Mitchell K. Wolf, Roberta C. Hamme, Denis Gilbert, Igor Yashayaev, Virginie Thierry. Oxygen Saturation Surrounding Deep Water Formation Events in the Labrador Sea From Argo-O-2 Data. Global Biogeochemical Cycles, 2018, 32 (4), pp.635-653. ⟨10.1002/2017GB005829⟩. ⟨hal-04202123⟩
19 Consultations
12 Téléchargements

Altmetric

Partager

Gmail Mastodon Facebook X LinkedIn More