Global sea-to-air flux climatology for bromoform, dibromomethane and methyl iodide
Journal article, 2013

Volatile halogenated organic compounds containing bromine and iodine, which are naturally produced in the ocean, are involved in ozone depletion in both the troposphere and stratosphere. Three prominent compounds transporting large amounts of marine halogens into the atmosphere are bromoform (CHBr3), dibromomethane (CH2Br2) and methyl iodide (CH3I). The input of marine halogens to the stratosphere has been estimated from observations and modelling studies using low-resolution oceanic emission scenarios derived from top-down approaches. In order to improve emission inventory estimates, we calculate data-based high resolution global sea-to-air flux estimates of these compounds from surface observations within the HalOcAt (Halocarbons in the Ocean and Atmosphere) database (https://halocat.geomar.de/). Global maps of marine and atmospheric surface concentrations are derived from the data which are divided into coastal, shelf and open ocean regions. Considering physical and biogeochemical characteristics of ocean and atmosphere, the open ocean water and atmosphere data are classified into 21 regions. The available data are interpolated onto a 1 degrees x 1 degrees grid while missing grid values are interpolated with latitudinal and longitudinal dependent regression techniques reflecting the compounds' distributions. With the generated surface concentration climatologies for the ocean and atmosphere, global sea-to-air concentration gradients and sea-to-air fluxes are calculated. Based on these calculations we estimate a total global flux of 1.5/2.5 Gmol Br yr(-1) for CHBr3, 0.78/0.98 Gmol Br yr(-1) for CH2Br2 and 1.24/1.45 Gmol Br yr(-1) for CH3I (robust fit/ordinary least squares regression techniques). Contrary to recent studies, negative fluxes occur in each sea-to-air flux climatology, mainly in the Arctic and Antarctic regions. "Hot spots" for global polybromomethane emissions are located in the equatorial region, whereas methyl iodide emissions are enhanced in the subtropical gyre regions. Inter-annual and seasonal variation is contained within our flux calculations for all three compounds. Compared to earlier studies, our global fluxes are at the lower end of estimates, especially for bromoform. An under-representation of coastal emissions and of extreme events in our estimate might explain the mismatch between our bottom-up emission estimate and top-down approaches.

MARINE BOUNDARY-LAYER

HALOGENATED ORGANIC-COMPOUNDS

PHOTOCHEMICAL PRODUCTION

PHYTOPLANKTON CULTURES

STRATOSPHERIC BROMINE

TROPICAL TROPOPAUSE LAYER

GAS-EXCHANGE

WIND-SPEED

ATLANTIC-OCEAN

OZONE DEPLETION

Author

F. Ziska

Helmholtz

B. Quack

Helmholtz

Katarina Abrahamsson

Chalmers, Chemical and Biological Engineering, Analytical Chemistry

S. D. Archer

Plymouth Marine Laboratory

Bigelow Laboratory of Ocean Sciences

E. Atlas

University of Miami

T. A. Bell

University of California at Irvine (UCI)

J. H. Butler

National Oceanic and Atmospheric Administration

L. J. Carpenter

University of York

C. E. Jones

Kyoto University

University of York

N. R. P. Harris

University of Cambridge

H. Hepach

Helmholtz

K. G. Heumann

Johannes Gutenberg University Mainz

C. Hughes

Centre for Ocean and Atmospheric Sciences

J. Kuss

Institut fur Ostseeforschung Warnemunde

K. Krüger

Helmholtz

P. Liss

Centre for Ocean and Atmospheric Sciences

R. M. Moore

Dalhousie University

A. Orlikowska

Institut fur Ostseeforschung Warnemunde

S Raimund

Helmholtz

Adaptation et Diversite en Milieu Marin

C.E. Reeves

Centre for Ocean and Atmospheric Sciences

W. Reifenhäuser

Bayerisches Landesamt F╠łur Umwelt

A. D. Robinson

University of Cambridge

C. Schall

Fresenius Medical Care AG & Co. KGaA

T. Tanhua

Helmholtz

S. Tegtmeier

Helmholtz

S. Turner

Centre for Ocean and Atmospheric Sciences

L. Wang

Rutgers University

D. Wallace

Dalhousie University

J. Williams

Max Planck Society

H. Yamamoto

National Institute for Environmental Studies of Japan

Marine Works Japan Ltd.

S. Yvon-Lewis

Texas A&M University

Y. Yokouchi

National Institute for Environmental Studies of Japan

Atmospheric Chemistry and Physics

1680-7316 (ISSN) 1680-7324 (eISSN)

Vol. 13 17 8915-8934

Subject Categories

Meteorology and Atmospheric Sciences

DOI

10.5194/acp-13-8915-2013

More information

Latest update

4/27/2021