How Marine Emissions of Bromoform Impact the Remote Atmosphere.

Jia, Yue , Tegtmeier, Susann, Atlas, Elliot and Quack, Birgit (2019) How Marine Emissions of Bromoform Impact the Remote Atmosphere. Open Access Atmospheric Chemistry and Physics, 19 (17). pp. 11089-11103. DOI 10.5194/acp-19-11089-2019.

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Supplementary data:

Abstract

It is an open question how localized elevated emissions of bromoform (CHBr3) and other very short-lived halocarbons (VSLHs), found in coastal and upwelling regions, and low background emissions, typically found over the open ocean, impact the atmospheric VSLH distribution. In this study, we use the Lagrangian dispersion model FLEXPART to simulate atmospheric CHBr3 resulting from assumed uniform background emissions, and from elevated emissions consistent with those derived during three tropical cruise campaigns.

The simulations demonstrate that the atmospheric CHBr3 distributions in the uniform background emissions scenario are highly variable with high mixing ratios appearing in regions of convergence or low wind speed. This relation holds on regional and global scales.

The impact of localized elevated emissions on the atmospheric CHBr3 distribution varies significantly from campaign to campaign. The estimated impact depends on the strength of the emissions and the meteorological conditions. In the open waters of the western Pacific and Indian oceans, localized elevated emissions only slightly increase the background concentrations of atmospheric CHBr3, even when 1∘ wide source regions along the cruise tracks are assumed. Near the coast, elevated emissions, including hot spots up to 100 times larger than the uniform background emissions, can be strong enough to be distinguished from the atmospheric background. However, it is not necessarily the highest hot spot emission that produces the largest enhancement, since the tug-of-war between fast advective transport and local accumulation at the time of emission is also important.

Our results demonstrate that transport variations in the atmosphere itself are sufficient to produce highly variable VSLH distributions, and elevated VSLHs in the atmosphere do not always reflect a strong localized source. Localized elevated emissions can be obliterated by the highly variable atmospheric background, even if they are orders of magnitude larger than the average open ocean emissions.

Document Type: Article
Keywords: PARTICLE DISPERSION MODEL; SHORT-LIVED SUBSTANCES; CONVECTIVE-TRANSPORT; OCEANIC EMISSIONS; METHYL-IODIDE; PACIFIC-OCEAN; OZONE; BROMINE; CLIMATE; AIR
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-CH Chemical Oceanography
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-ME Maritime Meteorology
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.5194/acp-19-11089-2019
ISSN: 1680-7316
Projects: FLEXPART
Date Deposited: 14 Dec 2018 13:45
Last Modified: 19 Sep 2019 06:53
URI: http://oceanrep.geomar.de/id/eprint/45028

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