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Atmospheric isoprene measurements reveal larger-than-expected Southern Ocean emissions.

Published version
Peer-reviewed

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Authors

Bolas, Conor G 
Robinson, Andrew D 
Tummon, Fiona 

Abstract

Isoprene is a key trace component of the atmosphere emitted by vegetation and other organisms. It is highly reactive and can impact atmospheric composition and climate by affecting the greenhouse gases ozone and methane and secondary organic aerosol formation. Marine fluxes are poorly constrained due to the paucity of long-term measurements; this in turn limits our understanding of isoprene cycling in the ocean. Here we present the analysis of isoprene concentrations in the atmosphere measured across the Southern Ocean over 4 months in the summertime. Some of the highest concentrations ( >500 ppt) originated from the marginal ice zone in the Ross and Amundsen seas, indicating the marginal ice zone is a significant source of isoprene at high latitudes. Using the United Kingdom Earth System Model we show that current estimates of sea-to-air isoprene fluxes underestimate observed isoprene by a factor >20. A daytime source of isoprene is required to reconcile models with observations. The model presented here suggests such an increase in isoprene emissions would lead to >8% decrease in the hydroxyl radical in regions of the Southern Ocean, with implications for our understanding of atmospheric oxidation and composition in remote environments, often used as proxies for the pre-industrial atmosphere.

Description

Funder: The Antarctic Circumnavigation Expedition was funded by the Swiss Polar Institute and Ferring Pharmaceuticals. A. Baccarini was supported by the SNSF Grant No. 200021_169090. J. Schmale holds the Ingvar Kamprad Chair for Extreme Environments Research. R. Simó holds a European Research Council Advanced Grant (ERC-2018-AdG #834162). The ICM-CSIC is supported by a “Severo Ochoa” Centre of Excellence grant (CEX2019-000928-S) from the Spanish government. This work used Monsoon2, a collaborative high-performance computing facility funded by the Met Office and the Natural Environment Research Council. This work used Joint Analysis System Meeting Infrastructure Needs (JASMIN), the UK collaborative data analysis facility. JW’s work was supported by the United Kingdom Research and Innovation (UKRI) Future Leaders Fellowship Programme awarded to Dr Maria Val Martin (MR/T019867/1)

Keywords

37 Earth Sciences, 3709 Physical Geography and Environmental Geoscience, 3701 Atmospheric Sciences, 3708 Oceanography, 13 Climate Action

Journal Title

Nat Commun

Conference Name

Journal ISSN

2041-1723
2041-1723

Volume Title

15

Publisher

Springer Science and Business Media LLC
Sponsorship
RCUK | Natural Environment Research Council (NERC) (NE/T006366/1)