Identification

Title

Mechanisms of low-frequency oxygen variability in the North Pacific

Abstract

This study investigates the mechanisms of interannual and decadal variability of dissolved oxygen (O-2) in the North Pacific using historical observations and a hindcast simulation using the Community Earth System Model. The simulated variability of upper ocean (200 m) O-2 is moderately correlated with observations where sampling density is relatively high. The dominant mode of O-2 variability explains 24.8% of the variance and is significantly correlated with the Pacific Decadal Oscillation (PDO) index (r = 0.68). Two primary mechanisms are hypothesized by which the PDO controls upper ocean O-2 variability. Vertical movement of isopycnals ("heave") drives O-2 variations in the deep tropics; isopycnal surfaces are depressed in the eastern tropics under the positive (El Nino-like) phase of PDO, leading to O-2 increases in the upper water column. In contrast to the tropics, changes in subduction are the primary control on extratropical O-2 variability. These hypotheses are tested by contrasting O-2 anomalies with the heave-induced component of variability calculated from potential density anomalies. Isopycnal heave is the leading control on O-2 variability in the tropics, but heave alone cannot fully explain the amplitude of tropical O-2 variability, likely indicating reinforcing changes from the biological O-2 consumption. Midlatitude O-2 variability indeed reflects ocean ventilation downstream of the subduction region where O-2 anomalies are correlated with the depth of winter mixed layer. These mechanisms, synchronized with the PDO, yield a basin-scale pattern of O-2 variability that are comparable in magnitude to the projected rates of ocean deoxygenation in this century under "unchecked" emission scenario.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.org/ark:/85065/d71v5j0k

codeSpace

Dataset language

eng

Spatial reference system

code identifying the spatial reference system

Classification of spatial data and services

Topic category

geoscientificInformation

Keywords

Keyword set

keyword value

Text

originating controlled vocabulary

title

Resource Type

reference date

date type

publication

effective date

2016-01-01T00:00:00Z

Geographic location

West bounding longitude

East bounding longitude

North bounding latitude

South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2019-02-01T00:00:00Z

Frequency of update

Quality and validity

Lineage

Conformity

Data format

name of format

version of format

Constraints related to access and use

Constraint set

Use constraints

Limitations on public access

None

Responsible organisations

Responsible party

contact position

OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

email address

opensky@ucar.edu

web address

http://opensky.ucar.edu/

name: homepage

responsible party role

pointOfContact

Metadata on metadata

Metadata point of contact