Sensitivity of Global Ocean Deoxygenation to Vertical and Isopycnal Mixing in an Ocean Biogeochemistry Model
Abstract
Large-scale loss of oxygen under global warming is termed “ocean deoxygenation” and is caused by the imbalance between physical supply and biological consumption of oxygen in the ocean interior. Significant progress has been made in the theoretical understanding of ocean deoxygenation; however, many questions remain unresolved. The oxygen change in the tropical thermocline is poorly understood, with diverging projections among different models. Physical oxygen supply is controlled by a suite of processes that transport oxygen-rich surface waters into the interior ocean, which is expected to weaken due to increasing stratification under global warming. Using a numerical model and a series of sensitivity experiments, the role of ocean mixing is examined in terms of effects on the mean state and the response to a transient warming. Both vertical and horizontal (isopycnal) mixing coefficients are systematically varied over a wide range, and the resulting oxygen distributions in equilibrated and transient simulations are examined. The spatial patterns of oxygen loss are sensitive to both vertical and isopycnal mixing, and the sign of tropical oxygen trend under climate warming can reverse depending on the choice of mixing parameters. An elevated level of isopycnal mixing disrupts the vertical advective-diffusive balance of the tropical thermocline, increasingmore »
- Authors:
-
[1];
[2];
[3];
[4]
- Georgia Institute of Technology, Atlanta, GA (United States)
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Princeton Univ., NJ (United States)
- National Center for Atmospheric Research (NCAR), Boulder, CO (United States)
- Publication Date:
- Research Org.:
- Georgia Institute of Technology, Atlanta, GA (United States); Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC), Biological and Environmental Research (BER); National Science Foundation (NSF)
- OSTI Identifier:
- 1864678
- Alternate Identifier(s):
- OSTI ID: 1864915; OSTI ID: 1866961
- Report Number(s):
- LA-UR-21-27311
Journal ID: ISSN 0886-6236; 1737158; 1737188; 1737282
- Grant/Contract Number:
- SC0021300; NSF-1737158; NSF-1737188; NSF-1737282; 89233218CNA000001
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Global Biogeochemical Cycles
- Additional Journal Information:
- Journal Volume: 36; Journal Issue: 4; Journal ID: ISSN 0886-6236
- Publisher:
- American Geophysical Union (AGU)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 58 GEOSCIENCES; Earth Sciences; ocean deoxygenation, ocean mixing, global warming
Citation Formats
Ito, T., Takano, Yohei, Deutsch, Curtis, and Long, Matthew C. Sensitivity of Global Ocean Deoxygenation to Vertical and Isopycnal Mixing in an Ocean Biogeochemistry Model. United States: N. p., 2022.
Web. doi:10.1029/2021gb007151.
Ito, T., Takano, Yohei, Deutsch, Curtis, & Long, Matthew C. Sensitivity of Global Ocean Deoxygenation to Vertical and Isopycnal Mixing in an Ocean Biogeochemistry Model. United States. https://doi.org/10.1029/2021gb007151
Ito, T., Takano, Yohei, Deutsch, Curtis, and Long, Matthew C. Sun .
"Sensitivity of Global Ocean Deoxygenation to Vertical and Isopycnal Mixing in an Ocean Biogeochemistry Model". United States. https://doi.org/10.1029/2021gb007151. https://www.osti.gov/servlets/purl/1864678.
@article{osti_1864678,
title = {Sensitivity of Global Ocean Deoxygenation to Vertical and Isopycnal Mixing in an Ocean Biogeochemistry Model},
author = {Ito, T. and Takano, Yohei and Deutsch, Curtis and Long, Matthew C.},
abstractNote = {Large-scale loss of oxygen under global warming is termed “ocean deoxygenation” and is caused by the imbalance between physical supply and biological consumption of oxygen in the ocean interior. Significant progress has been made in the theoretical understanding of ocean deoxygenation; however, many questions remain unresolved. The oxygen change in the tropical thermocline is poorly understood, with diverging projections among different models. Physical oxygen supply is controlled by a suite of processes that transport oxygen-rich surface waters into the interior ocean, which is expected to weaken due to increasing stratification under global warming. Using a numerical model and a series of sensitivity experiments, the role of ocean mixing is examined in terms of effects on the mean state and the response to a transient warming. Both vertical and horizontal (isopycnal) mixing coefficients are systematically varied over a wide range, and the resulting oxygen distributions in equilibrated and transient simulations are examined. The spatial patterns of oxygen loss are sensitive to both vertical and isopycnal mixing, and the sign of tropical oxygen trend under climate warming can reverse depending on the choice of mixing parameters. An elevated level of isopycnal mixing disrupts the vertical advective-diffusive balance of the tropical thermocline, increasing the mean state oxygen as well as the magnitude of the transient oxygen decline. These results provide first-order explanations for the diverging behaviors of simulated tropical oxygen with respect to ocean mixing parameters.},
doi = {10.1029/2021gb007151},
journal = {Global Biogeochemical Cycles},
number = 4,
volume = 36,
place = {United States},
year = {Sun Apr 03 00:00:00 EDT 2022},
month = {Sun Apr 03 00:00:00 EDT 2022}
}
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