Identification

Title

Effects of ozone isotopologue formation on the clumped-isotope composition of atmospheric O2

Abstract

Tropospheric (OO)-O-18-O-18 is an emerging proxy for past tropospheric ozone and free-tropospheric temperatures. The basis of these applications is the idea that isotope-exchange reactions in the atmosphere drive (OO)-O-18-O-18 abundances toward isotopic equilibrium. However, previous work used an offline box-model framework to explain the (OO)-O-18-O-18 budget, approximating the interplay of atmospheric chemistry and transport. This approach, while convenient, has poorly characterized uncertainties. To investigate these uncertainties, and to broaden the applicability of the (OO)-O-18-O-18 proxy, we developed a scheme to simulate atmospheric (OO)-O-18-O-18 abundances (quantified as increment (36) values) online within the GEOS-Chem chemical transport model. These results are compared to both new and previously published atmospheric observations from the surface to 33 km. Simulations using a simplified O-2 isotopic equilibration scheme within GEOS-Chem show quantitative agreement with measurements only in the middle stratosphere; modeled increment (36) values are too high elsewhere. Investigations using a comprehensive model of the O-O-2-O-3 isotopic photochemical system and proof-of-principle experiments suggest that the simple equilibration scheme omits an important pressure dependence to increment (36) values: the anomalously efficient titration of (OO)-O-18-O-18 to form ozone. Incorporating these effects into the online increment (36) calculation scheme in GEOS-Chem yields quantitative agreement for all available observations. While this previously unidentified bias affects the atmospheric budget of (OO)-O-18-O-18 in O-2, the modeled change in the mean tropospheric increment (36) value since 1850 CE is only slightly altered; it is still quantitatively consistent with the ice-core increment (36) record, implying that the tropospheric ozone burden increased less than 40% over the twentieth century.

Resource type

document

Resource locator

Unique resource identifier

code

http://n2t.net/ark:/85065/d7js9tzx

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

2021-07-27T00:00:00Z

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