Identification

Title

Isotopic ordering in atmospheric O2 as a tracer of ozone photochemistry and the tropical atmosphere

Abstract

The distribution of isotopes within O-2 molecules can be rapidly altered when they react with atomic oxygen. This mechanism is globally important: while other contributions to the global budget of O-2 impart isotopic signatures, the O(P-3)+O-2 reaction resets all such signatures in the atmosphere on subdecadal timescales. Consequently, the isotopic distribution within O-2 is determined by O-3 photochemistry and the circulation patterns that control where that photochemistry occurs. The variability of isotopic ordering in O-2 has not been established, however. We present new measurements of (OO)-O-18-O-18 in air (reported as (36) values) from the surface to 33km altitude. They confirm the basic features of the clumped-isotope budget of O-2: Stratospheric air has higher (36) values than tropospheric air (i.e., more (OO)-O-18-O-18), reflecting colder temperatures and fast photochemical cycling of O-3. Lower (36) values in the troposphere arise from photochemistry at warmer temperatures balanced by the influx of high-(36) air from the stratosphere. These observations agree with predictions derived from the GEOS-Chem chemical transport model, which provides additional insight. We find a link between tropical circulation patterns and regions where (36) values are reset in the troposphere. The dynamics of these regions influences lapse rates, vertical and horizontal patterns of O-2 reordering, and thus the isotopic distribution toward which O-2 is driven in the troposphere. Temporal variations in (36) values at the surface should therefore reflect changes in tropospheric temperatures, photochemistry, and circulation. Our results suggest that the tropospheric O-3 burden has remained within a 10% range since 1978.

Resource type

document

Resource locator

Unique resource identifier

code

https://n2t.org/ark:/85065/d7nc62zg

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

2016-10-27T00:00:00Z

Frequency of update

Quality and validity

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Conformity

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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