scholarly journals Influence of the Panama Seaway closure on large-scale ocean circulation and the tropical Pacific oxygen minimum zone during the Pliocene from model simulations

2021 ◽  
Author(s):  
Vyacheslav Khon ◽  
Babette Hoogakker ◽  
Birgit Schneider ◽  
Joachim Segschneider ◽  
Wonsun Park
Keyword(s):  
Ocean Circulation ◽  
Large Scale ◽  
Oxygen Minimum Zone ◽  
Tropical Pacific ◽  
Model Simulations ◽  
Minimum Zone ◽  
Panama Seaway ◽  
Oxygen Minimum ◽  
The Tropical Pacific

scholarly journals Oxygen minimum zone variations in the tropical Pacific during the Holocene

2015 ◽  
Vol 42 (20) ◽  
pp. 8530-8537 ◽  
Author(s):  
Xu Xu ◽  
Joachim Segschneider ◽  
Birgit Schneider ◽  
Wonsun Park ◽  
Mojib Latif
Keyword(s):  
Oxygen Minimum Zone ◽  
Tropical Pacific ◽  
The Holocene ◽  
Minimum Zone ◽  
Oxygen Minimum ◽  
The Tropical Pacific

scholarly journals Diapycnal oxygen supply to the tropical North Atlantic oxygen minimum zone

2012 ◽  
Vol 9 (10) ◽  
pp. 14291-14325 ◽  
Author(s):  
T. Fischer ◽  
D. Banyte ◽  
P. Brandt ◽  
M. Dengler ◽  
G. Krahmann ◽  
...  
Keyword(s):  
North Atlantic ◽  
Large Scale ◽  
Oxygen Supply ◽  
Water Layer ◽  
Oxygen Minimum Zone ◽  
Depth Interval ◽  
Diapycnal Mixing ◽  
Tropical North Atlantic ◽  
Minimum Zone ◽  
Oxygen Minimum

Abstract. The replenishment of consumed oxygen in the open ocean oxygen minimum zone (OMZ) off West Africa in the tropical North Atlantic Ocean is studied, with a focus on oxygen transport across density surfaces (diapycnal flux). The latter is obtained from a large observational set of oxygen profiles and diapycnal mixing data from years 2008 to 2010. Diapycnal mixing is inferred from different sources: a large scale tracer release experiment, microstructure profiles, and shipboard acoustic current measurements plus density profiles. The average diapycnal diffusivity in the study area is 1 × 10−5 m2 s−1. No significant vertical gradient of average diapycnal diffusivities exists in the depth interval from 150 to 500 m. The diapycnal flux is found to contribute substantially to the oxygen supply of the OMZ. Within the OMZ core, 1.5 µmol kg−1 a−1 of oxygen is supplied via diapycnal mixing, contributing about a third of the total demand. The oxygen that is contributed via diapycnal mixing originates from oxygen that has been laterally supplied within the overlying Central Water layer by advective and eddy fluxes. Due to the existence of a separate shallow oxygen minimum at about 100 m depth throughout most of the study area, there is no direct net vertical oxygen flux from the surface layer of the study area into the Central Water layer. Thus all oxygen supply of the OMZ is associated with remote pathways.

scholarly journals High-resolution modeling of the Eastern Tropical Pacific oxygen minimum zone: Sensitivity to the tropical oceanic circulation

2014 ◽  
Vol 119 (8) ◽  
pp. 5515-5532 ◽  
Author(s):  
Ivonne Montes ◽  
Boris Dewitte ◽  
Elodie Gutknecht ◽  
Aurélien Paulmier ◽  
Isabelle Dadou ◽  
...  
Keyword(s):  
High Resolution ◽  
Oxygen Minimum Zone ◽  
Tropical Pacific ◽  
Oceanic Circulation ◽  
Eastern Tropical Pacific ◽  
Minimum Zone ◽  
Oxygen Minimum

Impact of Resolution and Optimized ECCO Forcing on Simulations of the Tropical Pacific

2008 ◽  
Vol 25 (1) ◽  
pp. 131-147 ◽  
Author(s):  
I. Hoteit ◽  
B. Cornuelle ◽  
V. Thierry ◽  
D. Stammer
Keyword(s):  
Ocean Circulation ◽  
General Circulation ◽  
Large Scale ◽  
Circulation Model ◽  
Tropical Pacific ◽  
Global Ocean ◽  
Massachusetts Institute Of Technology ◽  
Model Domain ◽  
Freshwater Fluxes ◽  
The Tropical Pacific

Abstract The sensitivity of the dynamics of a tropical Pacific Massachusetts Institute of Technology (MIT) general circulation model (MITgcm) to the surface forcing fields and to the horizontal resolution is analyzed. During runs covering the period 1992–2002, two different sets of surface forcing boundary conditions are used, obtained 1) from the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) reanalysis project and 2) from the Estimating the Circulation and Climate of the Ocean (ECCO) assimilation consortium. The “ECCO forcing” is the “NCEP forcing” adjusted by a state estimation procedure using the MITgcm with a 1° × 1° global grid and the adjoint method assimilating a multivariate global ocean dataset. The skill of the model is evaluated against ocean observations available in situ and from satellites. The model domain is limited to the tropical Pacific, with open boundaries located along 26°S, 26°N, and in the Indonesian throughflow. To account for large-scale changes of the ocean circulation, the model is nested in the global time-varying ocean state provided by the ECCO consortium on a 1° grid. Increasing the spatial resolution to 1/3° and using the ECCO forcing fields significantly improves many aspects of the circulation but produces overly strong currents in the western model domain. Increasing the resolution to 1/6° does not yield further improvements of model results. Using the ECCO heat and freshwater fluxes in place of NCEP products leads to improved time-mean model skill (i.e., reduced biases) over most of the model domain, underlining the important role of adjusted heat and freshwater fluxes for improving model representations of the tropical Pacific. Combinations of ECCO and NCEP wind forcing fields can improve certain aspects of the model solutions, but neither ECCO nor NCEP winds show clear overall superiority.

scholarly journals Evidences and drivers of ocean deoxygenation off Peru over recent past decades

2021 ◽  
Author(s):  
Dante Espinoza-Morriberón ◽  
Vincent Echevin ◽  
Dimitri Gutiérrez ◽  
Jorge Tam ◽  
Michelle Graco ◽  
...  
Keyword(s):  
Coupled Model ◽  
Oxygen Minimum Zone ◽  
Model Simulations ◽  
Subsurface Waters ◽  
Huge Impact ◽  
Minimum Zone ◽  
Northern Peru ◽  
Oxygen Minimum

Abstract Deoxygenation is a major threat to the coastal ocean health as it impacts marine life and key biogeochemical cycles. Understanding its drivers is crucial in the thriving and highly exploited Peru upwelling system, where naturally low-oxygenated subsurface waters form the so-called oxygen minimum zone, and a slight vertical shift in its upper limit may have a huge impact. Here we investigate the long-term deoxygenation trends in the upper part of the nearshore oxygen minimum zone off Peru over the period 1970-2008. We use a unique set of dissolved oxygen in situ observations and several high resolution regional dynamical-biogeochemical coupled model simulations. The upper part of the oxygen minimum zone appears to lose oxygen over the period, particularly off Northern Peru, a trend well reproduced by the model. Model simulations attribute the deoxygenation to the slowdown of the near-equatorial eastward currents, which transport oxygen toward the Peruvian shores. The large uncertainties in the estimation of this ventilation flux and the consequences for more recent and future deoxygenation trends are discussed.

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