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 F̈ur 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 8915-8934Subject Categories
Meteorology and Atmospheric Sciences
DOI
10.5194/acp-13-8915-2013