Sea-ice and brine formation in Storfjorden: Implications for the Arctic wintertime air—sea CO2 flux

Omar, Abdirahman M; Johannessen, Truls; Bellerby, R. G. J.; Olsen, Are; Anderson, Leif G.; Kivimäe, Caroline

doi:10.1029/158gm12

Cited by 26 publications

(46 citation statements)

References 25 publications

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“…The few existing studies of Norwegian fjords confirm the above picture; i.e. they act as an annual net sink for atmospheric CO 2 (Fransson et al, 2014;Omar et al, 2005).…”

Section: A M Omar Et Al: Aragonite Saturation States and Ph In Wesmentioning

confidence: 58%

“…However, only a few studies on the carbon cycle of Norwegian fjords exist and these are only from the high Arctic at Svalbard (Fransson et al, 2014;Omar et al, 2005). Generally, in the Northern Hemisphere, high latitude coastal regions are thought to be sinks for atmospheric CO 2 , while low-latitude regions are thought to be CO 2 sources Cai et al, 2006;Chavez et al, 2007;Chen and Borges, 2009).…”

Section: A M Omar Et Al: Aragonite Saturation States and Ph In Wesmentioning

confidence: 99%

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Aragonite saturation states and pH in western Norwegian fjords: seasonal cycles and controlling factors, 2005–2009

et al. 2016

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Abstract. The uptake of anthropogenic carbon dioxide (CO2) by the ocean leads to a process known as ocean acidification (OA), which lowers the aragonite saturation state (ΩAr) and pH, and this is poorly documented in coastal environments including fjords due to lack of appropriate observations.Here we use weekly underway data from the Voluntary Observing Ships (VOS) program covering the period 2005–2009 combined with data from research cruises to estimate ΩAr and pH values in several adjacent western Norwegian fjords, and to evaluate how seawater CO2 chemistry drives their variations in response to physical and biological factors.The OA parameters in the surface waters of the fjords are subject to strong seasonal and spatially coherent variations. These changes are governed by the seasonal changes in temperature, salinity, formation and decay of organic matter, and vertical mixing with deeper, carbon-rich coastal water. Annual mean pH and ΩAr values were 8.13 and 2.21, respectively. The former varies from minimum values ( ≈  8.05) in late December – early January to maximum values of around 8.2 during early spring (March–April) as a consequence of the phytoplankton spring bloom, which reduces dissolved inorganic carbon (DIC). In the following months, pH decreases in response to warming. This thermodynamic decrease in pH is reinforced by the deepening of the mixed layer, which enables carbon-rich coastal water to reach the surface, and this trend continues until the low winter values of pH are reached again. ΩAr, on the other hand, reaches its seasonal maximum (> 2.5) in mid- to late summer (July–September), when the spring bloom is over and pH is decreasing. The lowest ΩAr values ( ≈  1.3–1.6) occur during winter (January–March), when both pH and sea surface temperature (SST) are low and DIC is its highest. Consequently, seasonal ΩAr variations align with those of SST and salinity normalized DIC (nDIC).We demonstrate that underway measurements of fugacity of CO2 in seawater (fCO2) and SST from VOS lines combined with high frequency observations of the complete carbonate system at strategically placed fixed stations provide an approach to interpolate OA parameters over large areas in the fjords of western Norway.

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“…The few existing studies of Norwegian fjords confirm the above picture; i.e. they act as an annual net sink for atmospheric CO 2 (Fransson et al, 2014;Omar et al, 2005).…”

Section: A M Omar Et Al: Aragonite Saturation States and Ph In Wesmentioning

confidence: 58%

Section: A M Omar Et Al: Aragonite Saturation States and Ph In Wesmentioning

confidence: 99%

Aragonite saturation states and pH in western Norwegian fjords: seasonal cycles and controlling factors, 2005–2009

et al. 2016

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“…A counterbalance to wintertime outgassing from polynyas and leads, may be wintertime net influx of carbon due to brine rejection during deep water formation (Anderson et al, 2004;Omar et al, 2005). Omar et al (2005), scaling results from Storfjorden, Svalbard, reported a wintertime influx of 2.3, 6.8 and 33 Tg C for coastal shelf ploynyas, central basin polynyas, and brine-rejection during ice formation in the seasonally sea-ice free areas of the Arctic, respectively.…”

Section: The Present Day Annual Arctic Ocean Co 2 Sink: Caveats and Cmentioning

confidence: 99%

“…As in the Barents Sea, the fall and winter rebound of seawater pCO 2 to values just below equilibrium with the atmosphere likely results from a continued uptake of CO 2 through gas exchange during sea-ice formation and brine rejection (Anderson et al, 2004;Omar et al, 2005) and vertical entrainment by mixing with CO 2 rich subsurface waters.…”

Section: Chukchi Sea Shelfmentioning

confidence: 99%

“…The East Siberian Sea shelf may be more highly influenced by these processes and hence more likely to be net heterotrophic and a source of CO 2 to the atmosphere. The Laptev Sea also has a permanent flaw lead polynya (Dmitrenko et al, 2005;Nitishinsky et al, 2008) that may contribute to ocean CO 2 uptake from the atmosphere during wintertime brine rejection and sea-ice formation as shown elsewhere (Anderson et al, 2004;Omar et al, 2005), but also winter outgassing of CO 2 from the polynya.…”

Section: Siberian Sea Shelves (Ie Kara Laptev and East Siberian Seas)mentioning

confidence: 99%

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The Arctic Ocean marine carbon cycle: evaluation of air-sea CO<sub>2</sub> exchanges, ocean acidification impacts and potential feedbacks

2009

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Abstract. At present, although seasonal sea-ice cover mitigates atmosphere-ocean gas exchange, the Arctic Ocean takes up carbon dioxide (CO 2 ) on the order of −66 to −199 Tg C year −1 (10 12 g C), contributing 5-14% to the global balance of CO 2 sinks and sources. Because of this, the Arctic Ocean has an important influence on the global carbon cycle, with the marine carbon cycle and atmosphere-ocean CO 2 exchanges sensitive to Arctic Ocean and global climate change feedbacks. In the near-term, further sea-ice loss and increases in phytoplankton growth rates are expected to increase the uptake of CO 2 by Arctic Ocean surface waters, although mitigated somewhat by surface warming in the Arctic. Thus, the capacity of the Arctic Ocean to uptake CO 2 is expected to alter in response to environmental changes driven largely by climate. These changes are likely to continue to modify the physics, biogeochemistry, and ecology of the Arctic Ocean in ways that are not yet fully understood. In surface waters, sea-ice melt, river runoff, cooling and uptake of CO 2 through air-sea gas exchange combine to decrease the calcium carbonate (CaCO 3 ) mineral saturation states ( ) of seawater while seasonal phytoplankton primary production (PP) mitigates this effect. Biological amplification of ocean acidification effects in subsurface waters, due to the remineralization of organic matter, is likely to reduce the ability of many species to produce CaCO 3 shells or tests with profound implications for Arctic marine ecosystems

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Brine formation in relation to climate changes and ice retreat during the last 15,000 years in Storfjorden, Svalbard, 76–78°N

Rasmussen

Thomsen

2014

Paleoceanography

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Storfjorden, Svalbard, is an area of intense brine formation. The brine is cold, dense, rich in oxygen and CO 2 , and has reduced pH. Storfjorden is unique because it contains well-preserved agglutinated foraminifera dating back to the beginning of the last deglaciation. We have investigated the distribution of calcareous and agglutinated benthic foraminifera, benthic oxygen and carbon isotopes, calcium carbonate, total organic carbon, and ice-rafted debris in five cores from Storfjorden comprising the Holocene and the deglaciation. The purpose of the study is to reconstruct brine formation in the past under different climate scenarios. The data indicate that in Storfjorden the ratio of agglutinated to calcareous benthic foraminifera can be taken as a measure of the strength of brine formation. The foraminiferal data, which are supported by stable isotopes, degree of fragmentation, and geochemical parameters, signify that brine formation intensified during cold periods and weakened during warm periods.

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Sea-ice and brine formation in Storfjorden: Implications for the Arctic wintertime air—sea CO2 flux

Cited by 26 publications

References 25 publications

Aragonite saturation states and pH in western Norwegian fjords: seasonal cycles and controlling factors, 2005–2009

Aragonite saturation states and pH in western Norwegian fjords: seasonal cycles and controlling factors, 2005–2009

The Arctic Ocean marine carbon cycle: evaluation of air-sea CO<sub>2</sub> exchanges, ocean acidification impacts and potential feedbacks

Brine formation in relation to climate changes and ice retreat during the last 15,000 years in Storfjorden, Svalbard, 76–78°N

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Sea-ice and brine formation in Storfjorden: Implications for the Arctic wintertime air—sea CO2 flux

Cited by 26 publications

References 25 publications

Aragonite saturation states and pH in western Norwegian fjords: seasonal cycles and controlling factors, 2005–2009

Aragonite saturation states and pH in western Norwegian fjords: seasonal cycles and controlling factors, 2005–2009

The Arctic Ocean marine carbon cycle: evaluation of air-sea CO&lt;sub&gt;2&lt;/sub&gt; exchanges, ocean acidification impacts and potential feedbacks

Brine formation in relation to climate changes and ice retreat during the last 15,000 years in Storfjorden, Svalbard, 76–78°N

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The Arctic Ocean marine carbon cycle: evaluation of air-sea CO<sub>2</sub> exchanges, ocean acidification impacts and potential feedbacks