Air-Sea CO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; fluxes on the Scotian Shelf: seasonal to multi-annual variability

Shadwick, E. H.; Thomas, Helmuth; Comeau, Adam; Craig, Susanne E.; Hunt, Christopher W; Salisbury, Joe

doi:10.5194/bg-7-3851-2010

Cited by 61 publications

(127 citation statements)

References 76 publications

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“…Observational studies reveal the Scotian Shelf to be a source of CO2 to the atmosphere, except during the period of the spring bloom (Shadwick et al, 2010(Shadwick et al, , 2011, see also Signorini et al, 2013 for discussion). Fluxes of CO2 to the atmosphere are highly variable outside of the spring bloom period (Shadwick et al, 2010).…”

Section: Oceanographic Settingmentioning

confidence: 99%

“…2d) demonstrate the intensity of the spring bloom during the months of March/April. The timing of the bloom varies between these two months depending on several factors including the onset of stratification (Shadwick et al, 2010, Greenan et al, 2004. Once the phytoplankton bloom consumes the available nitrate, the assemblage is taken over by smaller phytoplankton that prosper in the higher temperature, lower nutrient conditions (Craig et al, 2015;Li et al, 2006).…”

Section: Oceanographic Settingmentioning

confidence: 99%

“…This short but intense bloom heavily influences carbon cycling on the Scotian shelf. During this period the region shifts from being a source of CO2 to the atmosphere to a sink because of the biological CO2 drawdown (Shadwick et al, 2010(Shadwick et al, , 2011. Chlorophyll a concentrations (Fig.…”

Section: Oceanographic Settingmentioning

confidence: 99%

“…The Scotian Shelf is a coastal ocean and these complex, multifactorial interactions result in challenges in determining the processes that control the high degree of variability reported in this region (Shadwick et al, 2010, Signorini et al, 2013, Shadwick and Thomas, 2014.…”

Section: Introductionmentioning

confidence: 99%

“…Recent studies of the Scotian Shelf have focused primarily on monthly, seasonal, and interannual variability of carbon cycling (Shadwick et al, 2010, Shadwick and Thomas, 2014, Craig et al, 2015, but these longer-term trends are overlain by significant short-term variability (e.g. Vandemark et al, 2011 concentrations and timing of the phytoplankton bloom (e.g.…”

Section: Introductionmentioning

confidence: 99%

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Hurricane Arthur and its effect on the short-term variability of pCO<sub>2</sub> on the Scotian Shelf, NW Atlantic

Lemay¹,

Thomas²,

Craig³

et al. 2017

Preprint

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The understanding of seasonal variability of carbon cycling on the Scotian Shelf, NW Atlantic Ocean, has improved in recent years, however, very little information is available regarding its short-term variability. In order to shed light on this aspect of carbon cycling on the Scotian Shelf we investigate the effects of Hurricane Arthur, which passed the region on July 5 At the surface, phytoplankton begin to grow more rapidly due to increased light. The combination of growth and mixing of low DIC water led to a short-term reduction in partial pressure of CO2 until wind speeds relaxed and allowed for the restratification of the upper water column. These Hurricane-related processes caused a (net-) CO2 uptake by the Scotian Shelf region that is comparable to the spring bloom, thus exerting a major impact on the annual CO2 flux budget.

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Section: Oceanographic Settingmentioning

confidence: 99%

Section: Oceanographic Settingmentioning

confidence: 99%

Section: Oceanographic Settingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Hurricane Arthur and its effect on the short-term variability of pCO<sub>2</sub> on the Scotian Shelf, NW Atlantic

Lemay¹,

Thomas²,

Craig³

et al. 2017

Preprint

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Regionalized global budget of the CO₂ exchange at the air‐water interface in continental shelf seas

Laruelle

Lauerwald

Pfeil

et al. 2014

Global Biogeochemical Cycles

216

260

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Over the past decade, estimates of the atmospheric CO 2 uptake by continental shelf seas were constrained within the 0.18-0.45 Pg C yr À1 range. However, most of those estimates are based on extrapolations from limited data sets of local flux measurements (n < 100). Here we propose to derive the CO 2 air-sea exchange of the shelf seas by extracting 3 · 10 6 direct surface ocean CO 2 measurements from the global database SOCAT (Surface Ocean CO 2 Atlas), atmospheric CO 2 values from GlobalVIEW and calculating gas transfer rates using readily available global temperature, salinity, and wind speed fields. We then aggregate our results using a global segmentation of the shelf in 45 units and 152 subunits to establish a consistent regionalized CO 2 exchange budget at the global scale. Within each unit, the data density determines the spatial and temporal resolutions at which the air-sea CO 2 fluxes are calculated and range from a 0.5°resolution in the best surveyed regions to a whole unit resolution in areas where data coverage is limited. Our approach also accounts, for the first time, for the partial sea ice cover of polar shelves. Our new regionalized global CO 2 sink estimate of 0.19 ± 0.05 Pg C yr À1 falls in the low end of previous estimates. Reported to an ice-free surface area of 22 · 10 6 km 2 , this value yields a flux density of 0.7 mol C m À2 yr À1 ,~40% more intense than that of the open ocean. Our results also highlight the significant contribution of Arctic shelves to this global CO 2 uptake (0.07 Pg C yr À1 ).

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Seasonality of biological and physical controls on surface ocean CO₂ from hourly observations at the Southern Ocean Time Series site south of Australia

Shadwick

Trull

Tilbrook

et al. 2015

Global Biogeochemical Cycles

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The Subantarctic Zone (SAZ), which covers the northern half of the Southern Ocean between the Subtropical and Subantarctic Fronts, is important for air-sea CO 2 exchange, ventilation of the lower thermocline, and nutrient supply for global ocean productivity. Here we present the first high-resolution autonomous observations of mixed layer CO 2 partial pressure (pCO 2 ) and hydrographic properties covering a full annual cycle in the SAZ. The amplitude of the seasonal cycle in pCO 2 (∼60 μatm), from near-atmospheric equilibrium in late winter to ∼330 μatm in midsummer, results from opposing physical and biological drivers. Decomposing these contributions demonstrates that the biological control on pCO 2 (up to 100 μatm), is 4 times larger than the thermal component and driven by annual net community production of 2.45 ± 1.47 mol C m −2 yr −1 . After the summer biological pCO 2 depletion, the return to near-atmospheric equilibrium proceeds slowly, driven in part by autumn entrainment into a deepening mixed layer and achieving full equilibration in late winter and early spring as respiration and advection complete the annual cycle. The shutdown of winter convection and associated mixed layer shoaling proceeds intermittently, appearing to frustrate the initiation of production. Horizontal processes, identified from salinity anomalies, are associated with biological pCO 2 signatures but with differing impacts in winter (when they reflect far-field variations in dissolved inorganic carbon and/or biomass) and summer (when they suggest promotion of local production by the relief of silicic acid or iron limitation). These results provide clarity on SAZ seasonal carbon cycling and demonstrate that the magnitude of the seasonal pCO 2 cycle is twice as large as that in the subarctic high-nutrient, low-chlorophyll waters, which can inform the selection of optimal global models in this region.

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Air-Sea CO<sub>2</sub> fluxes on the Scotian Shelf: seasonal to multi-annual variability

Cited by 61 publications

References 76 publications

Hurricane Arthur and its effect on the short-term variability of pCO<sub>2</sub> on the Scotian Shelf, NW Atlantic

Hurricane Arthur and its effect on the short-term variability of pCO<sub>2</sub> on the Scotian Shelf, NW Atlantic

Regionalized global budget of the CO₂ exchange at the air‐water interface in continental shelf seas

Seasonality of biological and physical controls on surface ocean CO₂ from hourly observations at the Southern Ocean Time Series site south of Australia

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Air-Sea CO&lt;sub&gt;2&lt;/sub&gt; fluxes on the Scotian Shelf: seasonal to multi-annual variability

Cited by 61 publications

References 76 publications

Hurricane Arthur and its effect on the short-term variability of pCO&lt;sub&gt;2&lt;/sub&gt; on the Scotian Shelf, NW Atlantic

Hurricane Arthur and its effect on the short-term variability of pCO&lt;sub&gt;2&lt;/sub&gt; on the Scotian Shelf, NW Atlantic

Regionalized global budget of the CO2 exchange at the air‐water interface in continental shelf seas

Seasonality of biological and physical controls on surface ocean CO2 from hourly observations at the Southern Ocean Time Series site south of Australia

Contact Info

Product

Resources

About

Air-Sea CO<sub>2</sub> fluxes on the Scotian Shelf: seasonal to multi-annual variability

Hurricane Arthur and its effect on the short-term variability of pCO<sub>2</sub> on the Scotian Shelf, NW Atlantic

Hurricane Arthur and its effect on the short-term variability of pCO<sub>2</sub> on the Scotian Shelf, NW Atlantic

Regionalized global budget of the CO₂ exchange at the air‐water interface in continental shelf seas

Seasonality of biological and physical controls on surface ocean CO₂ from hourly observations at the Southern Ocean Time Series site south of Australia