Maintaining of the Eastern South Pacific Oxygen Minimum Zone (OMZ) off Chile Geophysical Research Letters

Aurélien Paulmier (1) , Diana Ruiz-Pino (1) , Veronique Garcon (2) , L. Farias

1 LOCEAN - Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques
2 LEGOS - Laboratoire d'études en Géophysique et océanographie spatiales

Processes regulating OMZs persistence in the oxygenated ocean remain poorly understood. Four cruises (21°-30°S) and fixed-point monitoring (36°S) between 2000 and 2002 using techniques adapted to O 2 conditions as low as 1 mM allow a preliminary analysis of the entire Chilean OMZ structure. A shallow OMZ is observed in the three studied areas, although its structure differs. Off northern and central Chile, the OMZ is a permanent feature, more pronounced at the coast than further offshore. On the shelf, it forms in spring and erodes in fall. A conceptual model of two intermittent active or passive phases (intense or low biogeochemical O 2 consumption) is proposed as a key mechanism for the local OMZ maintaining. The highest O 2 consumptions are paradoxically favoured at the oxycline when the OMZ is less intense as offshore and on the shelf in spring and fall, suggesting a control by O 2 availability of the OMZ remineralization.

Domaines: Planète et Univers [physics]

Aurélien Paulmier, Diana Ruiz-Pino, Veronique Garcon, L. Farias. Maintaining of the Eastern South Pacific Oxygen Minimum Zone (OMZ) off Chile Geophysical Research Letters. Geophysical Research Letters, 2006, 33, pp.33-L20601. ⟨10.1029/2006GL026801⟩. ⟨hal-00282580⟩