Sensitivity of Arctic sulfate aerosol and clouds to changes in future surface seawater dimethylsulfide concentrations
Dimethylsulfide (DMS), outgassed from ocean waters, plays an important role in the climate system, as it oxidizes to methane sulfonic acid (MSA) and sulfur dioxide (SO2), which can lead to the formation of sulfate aerosol. Newly formed sulfate aerosol resulting from DMS oxidation may grow by condens...
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Published in | Atmospheric chemistry and physics Vol. 19; no. 9; pp. 6419 - 6435 |
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Main Authors | , , , , |
Format | Journal Article |
Language | English |
Published |
Katlenburg-Lindau
Copernicus GmbH
16.05.2019
Copernicus Publications |
Subjects | |
Online Access | Get full text |
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Summary: | Dimethylsulfide (DMS), outgassed from ocean waters, plays an
important role in the climate system, as it oxidizes to methane sulfonic
acid (MSA) and sulfur dioxide (SO2), which can lead to the formation of
sulfate aerosol. Newly formed sulfate aerosol resulting from DMS oxidation
may grow by condensation of gases, in-cloud oxidation, and coagulation to
sizes where they may act as cloud condensation nuclei (CCN) and influence
cloud properties. Under future global warming conditions, sea ice in the
Arctic region is expected to decline significantly, which may lead to
increased emissions of DMS from the open ocean and changes in cloud regimes.
In this study we evaluate impacts of DMS on Arctic sulfate aerosol budget,
changes in cloud droplet number concentration (CDNC), and cloud radiative
forcing in the Arctic region under current and future sea ice conditions
using an atmospheric global climate model. Given that future DMS
concentrations are highly uncertain, several simulations with different
surface seawater DMS concentrations and spatial distributions in the Arctic
were performed in order to determine the sensitivity of sulfate aerosol
budgets, CDNC, and cloud radiative forcing to Arctic surface seawater DMS
concentrations. For any given amount and distribution of Arctic surface
seawater DMS, similar amounts of sulfate are produced by oxidation of DMS
in 2000 and 2050 despite large increases in DMS emission in the latter period
due to sea ice retreat in the simulations. This relatively low sensitivity
of sulfate burden is related to enhanced sulfate wet removal by
precipitation in 2050. However simulated aerosol nucleation rates are higher
in 2050, which results in an overall increase in CDNC and substantially more
negative cloud radiative forcing. Thus potential future reductions in sea
ice extent may cause cloud albedos to increase, resulting in a negative
climate feedback on radiative forcing in the Arctic associated with ocean DMS emissions. |
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ISSN: | 1680-7324 1680-7316 1680-7324 |
DOI: | 10.5194/acp-19-6419-2019 |