Implications of sea-ice biogeochemistry for oceanic production and emissions of dimethyl sulfide in the Arctic
Sea ice represents an additional oceanic source of the climatically active gas dimethyl sulfide (DMS) for the Arctic atmosphere. To what extent this source contributes to the dynamics of summertime Arctic clouds is, however, not known due to scarcity of field measurements. In this study, we devel...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2017-06-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/14/3129/2017/bg-14-3129-2017.pdf |
| Summary: | Sea ice represents an additional oceanic source of the climatically active
gas dimethyl sulfide (DMS) for the Arctic atmosphere. To what extent this
source contributes to the dynamics of summertime Arctic clouds is, however,
not known due to scarcity of field measurements. In this study, we developed
a coupled sea ice–ocean ecosystem–sulfur cycle model to investigate the
potential impact of bottom-ice DMS and its precursor
dimethylsulfoniopropionate (DMSP) on the oceanic production and emissions of
DMS in the Arctic. The results of the 1-D model simulation were compared with
field data collected during May and June of 2010 in Resolute Passage. Our
results reproduced the accumulation of DMS and DMSP in the bottom ice during
the development of an ice algal bloom. The release of these sulfur species
took place predominantly during the earlier phase of the melt period,
resulting in an increase of DMS and DMSP in the underlying water column prior
to the onset of an under-ice phytoplankton bloom. Production and removal
rates of processes considered in the model are analyzed to identify the
processes dominating the budgets of DMS and DMSP both in the bottom ice and
the underlying water column. When openings in the ice were taken into
account, the simulated sea–air DMS flux during the melt period was dominated
by episodic spikes of up to 8.1 µmol m<sup>−2</sup> d<sup>−1</sup>. Further
model simulations were conducted to assess the effects of the incorporation
of sea-ice biogeochemistry on DMS production and emissions, as well as the
sensitivity of our results to changes of uncertain model parameters of the
sea-ice sulfur cycle. The results highlight the
importance of taking into account both the sea-ice sulfur cycle and ecosystem
in the flux estimates of oceanic DMS near the ice margins and identify key
uncertainties in processes and rates that should be better constrained by new
observations. |
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| ISSN: | 1726-4170 1726-4189 |