Identification

Title

Impacts of ENSO on air-sea oxygen exchange: Observations and mechanisms

Abstract

Models and observations of atmospheric potential oxygen (APO similar or equal to O-2 + 1.1 * CO2) are used to investigate the influence of El Nino-Southern Oscillation (ENSO) on air-sea O-2 exchange. An atmospheric transport inversion of APO data from the Scripps flask network shows significant interannual variability in tropical APO fluxes that is positively correlated with the Nino3.4 index, indicating anomalous ocean outgassing of APO during El Nino. Hindcast simulations of the Community Earth System Model (CESM) and the Institut Pierre-Simon Laplace model show similar APO sensitivity to ENSO, differing from the Geophysical Fluid Dynamics Laboratory model, which shows an opposite APO response. In all models, O-2 accounts for most APO flux variations. Detailed analysis in CESM shows that the O-2 response is driven primarily by ENSO modulation of the source and rate of equatorial upwelling, which moderates the intensity of O-2 uptake due to vertical transport of low-O-2 waters. These upwelling changes dominate over counteracting effects of biological productivity and thermally driven O-2 exchange. During El Nino, shallower and weaker upwelling leads to anomalous O-2 outgassing, whereas deeper and intensified upwelling during La Nina drives enhanced O-2 uptake. This response is strongly localized along the central and eastern equatorial Pacific, leading to an equatorial zonal dipole in atmospheric anomalies of APO. This dipole is further intensified by ENSO-related changes in winds, reconciling apparently conflicting APO observations in the tropical Pacific. These findings suggest a substantial and complex response of the oceanic O-2 cycle to climate variability that is significantly (> 50%) underestimated in magnitude by ocean models.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7vx0jxx

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

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South bounding latitude

Temporal reference

Temporal extent

Begin position

End position

Dataset reference date

date type

publication

effective date

2017-05-01T00:00:00Z

Frequency of update

Quality and validity

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Conformity

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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