scholarly journals A modelling study of temporal and spatial <i>p</i>CO<sub>2</sub> variability on the biologically active and temperature-dominated Scotian Shelf

2021 ◽  
Vol 18 (23) ◽  
pp. 6271-6286
Author(s):  
Krysten Rutherford ◽  
Katja Fennel ◽  
Dariia Atamanchuk ◽  
Douglas Wallace ◽  
Helmuth Thomas
Keyword(s):  
Surface Water ◽  
Coastal Upwelling ◽  
Gulf Of Maine ◽  
Dissolved Inorganic Carbon ◽  
General Assumption ◽  
Biologically Active ◽  
Source Surface ◽  
Scotian Shelf ◽  
Temporal And Spatial ◽  
Carbon Dioxide Co2

Abstract. Continental shelves are thought to be affected disproportionately by climate change and are a large contributor to global air–sea carbon dioxide (CO2) fluxes. It is often reported that low-latitude shelves tend to act as net sources of CO2, whereas mid- and high-latitude shelves act as net sinks. Here, we combine a high-resolution regional model with surface water time series and repeat transect observations from the Scotian Shelf, a mid-latitude region in the northwest North Atlantic, to determine what processes are driving the temporal and spatial variability of partial pressure of CO2 (pCO2) on a seasonal scale. In contrast to the global trend, the Scotian Shelf acts as a net source. Surface pCO2 undergoes a strong seasonal cycle with an amplitude of ∼ 200–250 µatm. These changes are associated with both a strong biological drawdown of dissolved inorganic carbon (DIC) in spring (corresponding to a decrease in pCO2 of 100–200 µatm) and pronounced effects of temperature, which ranges from 0 ∘C in the winter to near 20 ∘C in the summer, resulting in an increase in pCO2 of ∼ 200–250 µatm. Throughout the summer, events with low surface water pCO2 occur associated with coastal upwelling. This effect of upwelling on pCO2 is also in contrast to the general assumption that upwelling increases surface pCO2 by delivering DIC-enriched water to the surface. Aside from these localized events, pCO2 is relatively uniform across the shelf. Our model agrees with regional observations, reproduces seasonal patterns of pCO2, and simulates annual outgassing of CO2 from the ocean of +1.7±0.2 mol C m−2 yr−1 for the Scotian Shelf, net uptake of CO2 by the ocean of -0.5±0.2 mol C m−2 yr−1 for the Gulf of Maine, and uptake by the ocean of -1.3±0.3 mol C m−2 yr−1 for the Grand Banks.

scholarly journals A modeling study of temporal and spatial <i>p</i>CO<sub>2</sub> variability on the biologically active and temperature-dominated Scotian Shelf

2021 ◽  
Author(s):  
Krysten Rutherford ◽  
Katja Fennel ◽  
Dariia Atamanchuk ◽  
Douglas Wallace ◽  
Helmuth Thomas
Keyword(s):  
Surface Water ◽  
Coastal Upwelling ◽  
Gulf Of Maine ◽  
Dissolved Inorganic Carbon ◽  
Co2 Flux ◽  
General Assumption ◽  
Biologically Active ◽  
Source Surface ◽  
Scotian Shelf ◽  
Temporal And Spatial

Abstract. Continental shelves are thought to be affected disproportionately by climate change and are a large contributor to global air-sea carbon dioxide (CO2) fluxes. It is often reported that low-latitude shelves tend to act as net sources of CO2 whereas mid- and high-latitude shelves act as net sinks. Here, we combine a high-resolution regional model with surface water time-series and repeat transect observations from the Scotian Shelf, a mid-latitude region in the northwest North Atlantic, to determine what processes are driving the temporal and spatial variability of partial pressure of CO2 (pCO2). In contrast to the global trend, the Scotian Shelf acts as a net source. Surface pCO2 undergoes a strong seasonal cycle associated with both a strong biological drawdown of Dissolved Inorganic Carbon (DIC) in spring, and pronounced effects of temperature, which ranges from 0 °C in the winter to near 20 °C in the summer. Throughout the summer, events with low surface-water pCO2 occur nearshore associated with coastal upwelling. This effect of upwelling on pCO2 is also in contrast to the general assumption that upwelling increases surface pCO2 by delivering DIC-enriched water to the surface. Aside from these localized events, pCO2 is relatively uniform across the shelf. Our model agrees with regional observations, reproduces seasonal patterns of pCO2, and simulates annual outgassing of CO2 from the ocean of +1.9 ± 0.2 mol C m−2 yr−1 for the Scotian Shelf, net neutral CO2 flux of −0.09 ± 0.16 mol C m−2 yr−1 for the Gulf of Maine and uptake by the ocean of −0.88 ± 0.4 mol C m−2 yr−1 for the Grand Banks.

Seasonal variability of dissolved inorganic carbon and surface water pCO2 in the Scotian Shelf region of the Northwestern Atlantic

2011 ◽  
Vol 124 (1-4) ◽  
pp. 23-37 ◽  
Author(s):  
E.H. Shadwick ◽  
H. Thomas ◽  
K. Azetsu-Scott ◽  
B.J.W. Greenan ◽  
E. Head ◽  
...  
Keyword(s):  
Surface Water ◽  
Seasonal Variability ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Scotian Shelf ◽  
Shelf Region

Sources of Water Contributed to the Bay of Fundy by Surface Circulation

1960 ◽  
Vol 17 (2) ◽  
pp. 181-197 ◽  
Author(s):  
Dean F. Bumpus
Keyword(s):  
Surface Water ◽  
Annual Cycle ◽  
Gulf Of Maine ◽  
Surface Flow ◽  
Bay Of Fundy ◽  
Georges Bank ◽  
Scotian Shelf ◽  
Eastern Side ◽  
Surface Circulation ◽  
Surface Drift

The returns from the 35,000 drift bottles launched in the Gulf of Maine area since 1919 have been analyzed to determine the annual cycle of surface drift. The source of surface flow into the Bay of Fundy expands from a minimum during January in the offing of the eastern side of the bay to a maximum in May which includes most of Georges Bank, the Gulf of Maine and the southwestern Scotian Shelf, then commencing in September gradually contracts toward the minimum.Secular variations in the removal of surface water from the Bay of Fundy, indicative of changes in the Maine eddy, were noted during 1957 and 1958.

Coastal Adaptations to the Northern Gulf of Maine and Southern Scotian Shelf

2019 ◽  
pp. 44-80
Author(s):  
Matthew W. Betts ◽  
David W. Black ◽  
Brian Robinson ◽  
Arthur Spiess ◽  
Victor D. Thompson
Keyword(s):  
Surface Water ◽  
Sea Level Rise ◽  
Sea Level ◽  
Gulf Of Maine ◽  
Woodland Period ◽  
Late Archaic ◽  
Scotian Shelf ◽  
Near Shore ◽  
Coastal Adaptations ◽  
Cultural Shifts

The northern Gulf of Maine (NGOM) and its watershed have attracted humans for the last 12,500 years (cal BP), and evidence of Palaeoindian marine economies is well established in adjacent regions by ca. 8000 cal BP. Sea level rise (SLR) has obscured understandings of early coastal adaptations, although underwater research and some near-shore sites are providing important insights. The earliest evidence from surviving shell middens dates to ca. 5000 cal BP, and reveals that shellfish collecting and the seasonal exploitation of benthopelagic fish were important throughout the Late Maritime Archaic and Maritime Woodland periods. However, significant economic shifts have occurred. In particular, a Late Archaic focus on marine swordfish hunting was replaced by a dramatic increase in inshore seal hunting in the Maritime Woodland period. After ca. 3100 cal BP, inshore fishing for cod, flounder, sculpin, sturgeon and other species intensified. During the Late Maritime Woodland period, shellfish exploitation declined somewhat and the hunting of small seals, and, in some areas, white-tailed deer, increased sharply. The extent and nature of coastal economies in the NGOM was controlled, in part, by SLR, increasing tidal amplitude, and concomitant changes in surface-water temperatures, in tandem with broad regional cultural shifts.

scholarly journals Calcium carbonate saturation in the surface water of the Arctic Ocean: undersaturation in freshwater influenced shelves

2009 ◽  
Vol 6 (11) ◽  
pp. 2421-2431 ◽  
Author(s):  
M. Chierici ◽  
A. Fransson
Keyword(s):  
Calcium Carbonate ◽  
Surface Water ◽  
Cold Water ◽  
Dissolved Inorganic Carbon ◽  
Chukchi Sea ◽  
Total Alkalinity ◽  
The Arctic ◽  
Subsurface Water ◽  
Chukchi Peninsula ◽  
Bering Strait

Abstract. In the summer of 2005, we sampled surface water and measured pH and total alkalinity (AT) underway aboard IB Oden along the Northwest Passage from Cape Farewell (South Greenland) to the Chukchi Sea. We investigated the variability of carbonate system parameters, focusing particularly on carbonate concentration [CO32−] and calcium carbonate saturation states, as related to freshwater addition, biological processes and physical upwelling. Measurements on AT, pH at 15°C, salinity (S) and sea surface temperature (SST), were used to calculate total dissolved inorganic carbon (CT), [CO32−] and the saturation of aragonite (ΩAr) and calcite (ΩCa) in the surface water. The same parameters were measured in the water column of the Bering Strait. Some surface waters in the Canadian Arctic Archipelago (CAA) and on the Mackenzie shelf (MS) were found to be undersaturated with respect to aragonite (ΩAr<1). In these areas, surface water was low in AT and CT (<1500 μmol kg−1) relative to seawater and showed low [CO32−]. The low saturation states were probably due to the likely the effect of dilution due to freshwater addition by sea ice melt (CAA) and river runoff (MS). High AT and CT and low pH, corresponded with the lowest [CO32−], ΩAr and ΩCa, observed near Cape Bathurst and along the South Chukchi Peninsula. This was linked to the physical upwelling of subsurface water with elevated CO2. The highest surface ΩAr and ΩCa of 3.0 and 4.5, respectively, were found on the Chukchi Sea shelf and in the cold water north of Wrangel Island, which is heavily influenced by high CO2 drawdown and lower CT from intense biological production. In the western Bering Strait, the cold and saline Anadyr Current carries water that is enriched in AT and CT from enhanced organic matter remineralization, resulting in the lowest ΩAr (~1.2) of the area.

scholarly journals Environmental control on the variability of DMS and DMSP in the Mauritanian upwelling region

2011 ◽  
Vol 8 (4) ◽  
pp. 8591-8618
Author(s):  
C. Zindler ◽  
I. Peeken ◽  
C. A. Marandino ◽  
H. W. Bange
Keyword(s):  
Nitrogen Limitation ◽  
Coastal Upwelling ◽  
Environmental Control ◽  
Hot Spot ◽  
Northwest Africa ◽  
Induced Stress ◽  
Temporal And Spatial Variability ◽  
Temporal And Spatial ◽  
A Minor ◽  
The Tropics

Abstract. Dimethylsulfide (DMS) and dissolved and particulate dimethylsulfoniopropionate (DMSPd, DMSPp) were measured in sea surface layer along the Mauritanian coast, Northwest Africa, during the upwelling season in February 2008. DMS, DMSPd and DMSPp surface concentrations of up to 10 nmol L−1, 15 nmol L−1 and 990 nmol L−1, respectively, were measured. The maximum DMSPp concentration is the highest reported from upwelling regions so far and indicates that the Mauritanian upwelling is a hot spot of DMSP and, thus, DMS production. Dinoflagellates were responsible for the DMS production. Other phytoplankton groups seemed to have only a minor or no influence on the DMS and DMSP production. Decreasing nitrogen (i.e. increasing nitrogen limitation) most likely triggered a switch from high DMSP production to high DMS production. It seems that both nitrogen limitation and the intensive solar radiation in the tropics induced stress in DMSP producing algae and activated their antioxidant system. Our results underline the importance of coastal upwelling regions as ecosystems with a pronounced temporal and spatial variability which result in high DMSP and DMS production.

scholarly journals Seasonal trends and phenology shifts in sea surface temperature on the North American northeastern continental shelf

Elem Sci Anth ◽  
2017 ◽  
Vol 5 ◽  
Author(s):  
Andrew C. Thomas ◽  
Andrew J. Pershing ◽  
Kevin D. Friedland ◽  
Janet A. Nye ◽  
Katherine E. Mills ◽  
...  
Keyword(s):  
Surface Temperature ◽  
Continental Shelf ◽  
Sea Surface Temperature ◽  
North American ◽  
Gulf Of Maine ◽  
Sea Surface ◽  
Scotian Shelf ◽  
Seasonal Differences ◽  
Study Region ◽  
The North

The northeastern North American continental shelf from Cape Hatteras to the Scotian Shelf is a region of globally extreme positive trends in sea surface temperature (SST). Here, a 33-year (1982–2014) time series of daily satellite SST data was used to quantify and map spatial patterns in SST trends and phenology over this shelf. Strongest trends are over the Scotian Shelf (&gt;0.6°C decade–1) and Gulf of Maine (&gt;0.4°C decade–1) with weaker trends over the inner Mid-Atlantic Bight (~0.3°C decade–1). Winter (January–April) trends are relatively weak, and even negative in some areas; early summer (May–June) trends are positive everywhere, and later summer (July–September) trends are strongest (~1.0°C decade–1). These seasonal differences shift the phenology of many metrics of the SST cycle. The yearday on which specific temperature thresholds (8° and 12°C) are reached in spring trends earlier, most strongly over the Scotian Shelf and Gulf of Maine (~ –0.5 days year–1). Three metrics defining the warmest summer period show significant trends towards earlier summer starts, later summer ends and longer summer duration over the entire study region. Trends in start and end dates are strongest (~1 day year–1) over the Gulf of Maine and Scotian Shelf. Trends in increased summer duration are &gt;2.0 days year–1 in parts of the Gulf of Maine. Regression analyses show that phenology trends have regionally varying links to the North Atlantic Oscillation, to local spring and summer atmospheric pressure and air temperature and to Gulf Stream position. For effective monitoring and management of dynamically heterogeneous shelf regions, the results highlight the need to quantify spatial and seasonal differences in SST trends as well as trends in SST phenology, each of which likely has implications for the ecological functioning of the shelf.

scholarly journals Inorganic carbon time series at Ocean Weather Station M in the Norwegian Sea

2007 ◽  
Vol 4 (4) ◽  
pp. 2929-2958 ◽  
Author(s):  
I. Skjelvan ◽  
E. Falck ◽  
F. Rey ◽  
S. B. Kringstad
Keyword(s):  
Surface Water ◽  
Deep Water ◽  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Sea Surface ◽  
Linear Regression Method ◽  
Weather Station ◽  
Arctic Water ◽  
Annual Increase ◽  
Norwegian Sea

Abstract. Dissolved inorganic carbon (CT) has been collected at Ocean Weather Station M (OWSM) in the Norwegian Sea since 2001. Seasonal variations in CT are confined to the upper 50 m, where the biology is active, and below this layer no clear seasonal signal is seen. From winter to summer the surface CT concentration typical drops from 2140 to about 2040 μmol kg−1, while a deep water CT concentration of about 2163 μmol kg−1 is measured throughout the year. Observations show an annual increase in salinity normalized carbon concentration (nCT) of 1.3±0.7 μmol kg−1 in the surface layer, which is equivalent to a pCO2 increase of 2.6±1.2 μatm yr−1, i.e. larger than the atmospheric increase in this area. Observations also show an annual increase in the deep water nCT of 0.57± 0.24 μmol kg−1, of which about a tenth is due to inflow of old Arctic water with larger amounts of remineralised matter. The remaining part has an anthropogenic origin and sources for this might be Greenland Sea surface water, Iceland Sea surface water, and/or recirculated Atlantic Water. By using an extended multi linear regression method (eMLR) it is verified that anthropogenic carbon has entered the whole water column at OWSM.

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