scholarly journals The Marine Radiocarbon Bomb Pulse Across the Temperate North Atlantic: A Compilation of Δ14C Time Histories from Arctica Islandica Growth Increments

Radiocarbon ◽  
2012 ◽  
Vol 54 (02) ◽  
pp. 165-186 ◽  
Author(s):  
James D Scourse ◽  
Alan D Wanamaker ◽  
Chris Weidman ◽  
Jan Heinemeier ◽  
Paula J Reimer ◽  
...  
Keyword(s):  
North Sea ◽  
Marine Environment ◽  
Mixed Layer ◽  
North Atlantic ◽  
German Bight ◽  
Freshwater Flux ◽  
Arctica Islandica ◽  
Growth Increments ◽  
Time Histories ◽  
Carbon Reservoir

Marine radiocarbon bomb-pulse time histories of annually resolved archives from temperate regions have been underexploited. We present here series of Δ14C excess from known-age annual increments of the long-lived bivalve molluskArctica islandicafrom 4 sites across the coastal North Atlantic (German Bight, North Sea; Troms⊘, north Norway; Siglufjordur, north Icelandic shelf; Grimsey, north Icelandic shelf) combined with published series from Georges Bank and Sable Bank (NW Atlantic) and the Oyster Ground (North Sea). The atmospheric bomb pulse is shown to be a step-function whose response in the marine environment is immediate but of smaller amplitude and which has a longer decay time as a result of the much larger marine carbon reservoir. Attenuation is determined by the regional hydrographic setting of the sites, vertical mixing, processes controlling the isotopic exchange of14C at the air-sea boundary,14C content of the freshwater flux, primary productivity, and the residence time of organic matter in the sediment mixed layer. The inventories form a sequence from high magnitude-early peak (German Bight) to low magnitude-late peak (Grimsey). All series show a rapid response to the increase in atmospheric Δ14C excess but a slow response to the subsequent decline resulting from the succession of rapid isotopic air-sea exchange followed by the more gradual isotopic equilibration in the mixed layer due to the variable marine carbon reservoir and incorporation of organic carbon from the sediment mixed layer. The data constitute calibration scries for the use of the bomb pulse as a high-resolution dating tool in the marine environment and as a tracer of coastal ocean water masses.

scholarly journals The Marine Radiocarbon Bomb Pulse Across the Temperate North Atlantic: A Compilation of Δ14C Time Histories fromArctica IslandicaGrowth Increments

Radiocarbon ◽  
2012 ◽  
Vol 54 (2) ◽  
pp. 165-186 ◽  
Author(s):  
James D Scourse ◽  
Alan D Wanamaker ◽  
Chris Weidman ◽  
Jan Heinemeier ◽  
Paula J Reimer ◽  
...  
Keyword(s):  
North Sea ◽  
Marine Environment ◽  
Mixed Layer ◽  
North Atlantic ◽  
German Bight ◽  
Freshwater Flux ◽  
Arctica Islandica ◽  
Oyster Ground ◽  
Time Histories ◽  
Carbon Reservoir

Marine radiocarbon bomb-pulse time histories of annually resolved archives from temperate regions have been underexploited. We present here series of Δ14C excess from known-age annual increments of the long-lived bivalve molluskArctica islandicafrom 4 sites across the coastal North Atlantic (German Bight, North Sea; Troms⊘, north Norway; Siglufjordur, north Icelandic shelf; Grimsey, north Icelandic shelf) combined with published series from Georges Bank and Sable Bank (NW Atlantic) and the Oyster Ground (North Sea). The atmospheric bomb pulse is shown to be a step-function whose response in the marine environment is immediate but of smaller amplitude and which has a longer decay time as a result of the much larger marine carbon reservoir. Attenuation is determined by the regional hydrographic setting of the sites, vertical mixing, processes controlling the isotopic exchange of14C at the air-sea boundary,14C content of the freshwater flux, primary productivity, and the residence time of organic matter in the sediment mixed layer. The inventories form a sequence from high magnitude-early peak (German Bight) to low magnitude-late peak (Grimsey). All series show a rapid response to the increase in atmospheric Δ14C excess but a slow response to the subsequent decline resulting from the succession of rapid isotopic air-sea exchange followed by the more gradual isotopic equilibration in the mixed layer due to the variable marine carbon reservoir and incorporation of organic carbon from the sediment mixed layer. The data constitute calibration scries for the use of the bomb pulse as a high-resolution dating tool in the marine environment and as a tracer of coastal ocean water masses.

Bivalves indicate that the North Atlantic was under stress before the onset of the Little Ice Age

2021 ◽  
Author(s):  
Beatriz Arellano Nava ◽  
Paul R. Halloran ◽  
Chris A. Boulton ◽  
Timothy M. Lenton
Keyword(s):  
Marine Environment ◽  
North Atlantic ◽  
Little Ice Age ◽  
Stable State ◽  
Volcanic Eruptions ◽  
Ice Age ◽  
Last Millennium ◽  
The North ◽  
Growth Increments ◽  
Negative Feedbacks

<p>The last millennium was characterised by a cooling from the Medieval Warm Period into the Little Ice Age. While strong volcanic eruptions could have triggered the onset of the Little Ice Age by reducing solar irradiance, modelling experiments suggest that it was amplified and maintained by sea ice-ocean feedbacks, including a potential abrupt weakening of the subpolar gyre. The weakening of negative feedbacks that maintain a system in a stable state, prior to an abrupt transition, can be detected as an increase in temporal autocorrelation and variability. Here we use an annually-resolved and absolutely dated shell-derived record from the North Icelandic Shelf that spans the last millennium, to detect such a loss of resilience in the marine environment leading up to the Little Ice Age transition. We find a significant increase in autocorrelation and variance in bivalve growth increments and oxygen isotopes before the transition, providing evidence consistent with loss of stability in the marine environment. This supports the idea that internal feedbacks played an important role in the Little Ice Age onset.</p>

scholarly journals First-Order Scaling Law for Potential Vorticity Extraction due to Wind

2012 ◽  
Vol 42 (8) ◽  
pp. 1303-1312 ◽  
Author(s):  
Bruno Deremble ◽  
W. K. Dewar
Keyword(s):  
Mixed Layer ◽  
North Atlantic ◽  
Potential Vorticity ◽  
Scaling Law ◽  
Freshwater Flux ◽  
Sources And Sinks ◽  
First Order ◽  
The North ◽  
Wind Driven Currents ◽  
The Impact

Abstract Surface sources and sinks of potential vorticity (PV) have been examined recently in various publications. These are normally identified as the mechanical and buoyant PV fluxes with the former scaled according to wind stress and the latter from buoyancy flux. The authors here examine a PV source that is often overlooked: namely, the diabatically forced source due to wind-driven deepening. Based on an idealized model of the mixed layer, the rate of deepening of the mixed layer due to wind is translated into PV extraction. The authors propose the first-order scaling law as an estimate of the net PV flux due to diabatic wind effects in the absence of other buoyancy effects. This law is verified and calibrated in several numerical experiments. Then, the authors compare the magnitude of the PV extraction due to wind to the other factors responsible for PV input/output: namely, air–sea heat flux, freshwater flux, and Ekman wind-driven currents. Finally, to illustrate the impact of the mixing induced by wind, the authors conclude with a global air–sea PV budget in the North Atlantic basin. The wind-driven diabatic PV flux is found to be comparable to all other sources in all cases and is distinguished by acting only to extract PV.

scholarly journals Is there a reliable taphonomic clock in the temperate North Atlantic? An example from a North Sea population of the mollusc Arctica islandica

2020 ◽  
Vol 560 ◽  
pp. 109975
Author(s):  
Paul G. Butler ◽  
Nicole M. Fraser ◽  
James D. Scourse ◽  
Christopher A. Richardson ◽  
Charlotte Bryant ◽  
...  
Keyword(s):  
North Sea ◽  
North Atlantic ◽  
Arctica Islandica

Seasonal lipid dynamics of the shrimps Crangon crangon and Pandalus montagui in the German Bight (North Sea)

2019 ◽  
Vol 625 ◽  
pp. 41-52 ◽  
Author(s):  
D Martínez-Alarcón ◽  
R Saborowski ◽  
E Melis ◽  
W Hagen
Keyword(s):  
North Sea ◽  
German Bight ◽  
Crangon Crangon ◽  
Lipid Dynamics

scholarly journals Response of Freshwater Flux and Sea Surface Salinity to Variability of the Atlantic Warm Pool

2013 ◽  
Vol 26 (4) ◽  
pp. 1249-1267 ◽  
Author(s):  
Chunzai Wang ◽  
Liping Zhang ◽  
Sang-Ki Lee
Keyword(s):  
Central America ◽  
North Atlantic ◽  
Warm Pool ◽  
Sea Surface ◽  
Sea Surface Salinity ◽  
Freshwater Flux ◽  
Surface Salinity ◽  
Atlantic Warm Pool ◽  
Mean Circulation ◽  
Circulation Dynamics

Abstract The response of freshwater flux and sea surface salinity (SSS) to the Atlantic warm pool (AWP) variations from seasonal to multidecadal time scales is investigated by using various reanalysis products and observations. All of the datasets show a consistent response for all time scales: A large (small) AWP is associated with a local freshwater gain (loss) to the ocean, less (more) moisture transport across Central America, and a local low (high) SSS. The moisture budget analysis demonstrates that the freshwater change is dominated by the atmospheric mean circulation dynamics, while the effect of thermodynamics is of secondary importance. Further decomposition points out that the contribution of the mean circulation dynamics primarily arises from its divergent part, which mainly reflects the wind divergent change in the low level as a result of SST change. In association with a large (small) AWP, warmer (colder) than normal SST over the tropical North Atlantic can induce anomalous low-level convergence (divergence), which favors anomalous ascent (decent) and thus generates more (less) precipitation. On the other hand, a large (small) AWP weakens (strengthens) the trade wind and its associated westward moisture transport to the eastern North Pacific across Central America, which also favors more (less) moisture residing in the Atlantic and hence more (less) precipitation. The results imply that variability of freshwater flux and ocean salinity in the North Atlantic associated with the AWP may have the potential to affect the Atlantic meridional overturning circulation.

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