scholarly journals Earthquakes drive large-scale submarine canyon development and sediment supply to deep-ocean basins

2018 ◽  
Vol 4 (3) ◽  
pp. eaar3748 ◽  
Author(s):  
Joshu J. Mountjoy ◽  
Jamie D. Howarth ◽  
Alan R. Orpin ◽  
Philip M. Barnes ◽  
David A. Bowden ◽  
...  
Keyword(s):  
Large Scale ◽  
Deep Ocean ◽  
Submarine Canyon ◽  
Sediment Supply

scholarly journals Deglacial carbon cycle changes observed in a compilation of 127 benthic <i>δ</i><sup>13</sup>C time series (20–6 ka)

2018 ◽  
Vol 14 (8) ◽  
pp. 1229-1252 ◽  
Author(s):  
Carlye D. Peterson ◽  
Lorraine E. Lisiecki
Keyword(s):  
Time Series ◽  
Carbon Cycle ◽  
Carbon Storage ◽  
Large Scale ◽  
Deep Ocean ◽  
Atmospheric Co2 ◽  
Last Deglaciation ◽  
Terrestrial Biosphere ◽  
Spatial Coverage ◽  
Ocean Carbon

Abstract. We present a compilation of 127 time series δ13C records from Cibicides wuellerstorfi spanning the last deglaciation (20–6 ka) which is well-suited for reconstructing large-scale carbon cycle changes, especially for comparison with isotope-enabled carbon cycle models. The age models for the δ13C records are derived from regional planktic radiocarbon compilations (Stern and Lisiecki, 2014). The δ13C records were stacked in nine different regions and then combined using volume-weighted averages to create intermediate, deep, and global δ13C stacks. These benthic δ13C stacks are used to reconstruct changes in the size of the terrestrial biosphere and deep ocean carbon storage. The timing of change in global mean δ13C is interpreted to indicate terrestrial biosphere expansion from 19–6 ka. The δ13C gradient between the intermediate and deep ocean, which we interpret as a proxy for deep ocean carbon storage, matches the pattern of atmospheric CO2 change observed in ice core records. The presence of signals associated with the terrestrial biosphere and atmospheric CO2 indicates that the compiled δ13C records have sufficient spatial coverage and time resolution to accurately reconstruct large-scale carbon cycle changes during the glacial termination.

scholarly journals Spatial scales of temperature and salinity variability estimated from Argo observations

2015 ◽  
Vol 12 (4) ◽  
pp. 1793-1814
Author(s):  
F. Ninove ◽  
P. Y. Le Traon ◽  
E. Remy ◽  
S. Guinehut
Keyword(s):  
Large Scale ◽  
Spatial Scales ◽  
Deep Ocean ◽  
General Tendency ◽  
Zero Crossing ◽  
Tropical Regions ◽  
Covariance Functions ◽  
Salinity Variability ◽  
First Time

Abstract. Argo observations from 2005 to 2013 are used to characterize spatial scales temperature and salinity variations from the surface down to 1500 m. Simulations are first performed to analyze the sensitivity of results to Argo sampling; they show that several years of Argo observations are required to estimate the spatial scales of ocean variability over 20° × 20° boxes. Spatial scales are then computed over several large scale areas. Zonal and meridional spatial scales (Lx and Ly which are also zero crossing of covariance functions) vary as expected with latitudes. Scales are of about 100 km at high latitudes and more of 700 km in the Indian and Pacific equatorial/tropical regions. Zonal and meridional scales are similar: except in these tropical/equatorial regions where zonal scales are much larger (by a factor of 2 to 3) than meridional scales. Spatial scales are the largest close to the surface and have a general tendency for temperature to increase in deeper layers. There are significant differences between temperature and salinity scales, in particular, in the deep ocean. Results are consistent with previous studies based on sparse in-situ observations or satellite altimetry. They provide, however, for the first time a global description of temperature and salinity scales of variability and a characterization of their variations according to depths.

Shifting ocean circulation warms the Subpolar North Atlantic since 2016

2021 ◽  
Author(s):  
Damien Desbruyères ◽  
Léon Chafik ◽  
Guillaume Maze
Keyword(s):  
Ocean Circulation ◽  
North Atlantic ◽  
Large Scale ◽  
Deep Ocean ◽  
Ocean Heat Uptake ◽  
Driving Mechanisms ◽  
Temperature Trends ◽  
Meridional Overturning ◽  
Ocean Observing

&lt;p&gt;The Subpolar North Atlantic (SPNA) is known for rapid reversals of decadal temperature trends, with ramifications encompassing the large-scale meridional overturning and gyre circulations, Arctic heat and mass balances, or extreme continental weather. Here, we combine datasets derived from sustained ocean observing systems (satellite and in situ), and idealized observation-based modelling (advection-diffusion of a passive tracer) and machine learning technique (ocean profile clustering) to document and explain the most-recent and ongoing cooling-to-warming transition of the SPNA. Following a gradual cooling of the region that was persisting since 2006, a surface-intensified and large-scale warming sharply emerged in 2016 following an ocean circulation shift that enhanced the northeastward penetration of warm and saline waters from the western subtropics. Driving mechanisms and ramification for deep ocean heat uptake will be discussed.&lt;/p&gt;

Deep-Ocean Exploitation Technology

1971 ◽  
Vol 8 (02) ◽  
pp. 145-158
Author(s):  
Raymond Kaufman
Keyword(s):  
Continental Shelf ◽  
Large Scale ◽  
Deep Ocean ◽  
Abandoned Mine ◽  
Economic Potential ◽  
Mining Method ◽  
Mine Shaft ◽  
Sea Floor ◽  
Ocean Mining ◽  
Air Lift

The paper discusses the latest techniques proposed for mining minerals from the deep ocean. Deep ocean is defined as the sea beyond the continental shelf, particularly areas of the sea floor exceeding 1200 ft in depth. The three principal deep-ocean minerals having economic potential in the immediate future are identified. Four recently proposed advanced deep-ocean mining concepts are presented. Use of the air-lift pump as a viable mining method is discussed and a large-scale air-lift pump experiment conducted in an abandoned mine shaft at Galax, Virginia is described. The principal features of the conversion of a small C1-M-AV1 type cargo ship to a deep-ocean mining prototype vessel, RV Deepsea Miner, is outlined.

Large-scale siliciclastic input during the Paleocene-Eocene Thermal Maximum in the North Sea Basin

2021 ◽  
Author(s):  
Simin Jin ◽  
David Kemp ◽  
David Jolley ◽  
Manuel Vieira ◽  
Chunju Huang
Keyword(s):  
Carbon Isotope ◽  
North Sea ◽  
Climate Warming ◽  
Large Scale ◽  
Time Lag ◽  
Sediment Supply ◽  
Deep Time ◽  
The North ◽  
Thermal Maximum ◽  
The North Sea

&lt;p&gt;The Paleocene-Eocene Thermal Maximum (PETM, ~56 Ma) was the most marked climate warming event of the Cenozoic, and a potentially useful deep time analogue for understanding environmental responses to anthropogenic carbon emissions and associated warming. The response of sedimentary systems to the large-scale climate changes of the PETM are, however, still uncertain. Here, we present an extremely thick (~140 m) record of the PETM in cores from a well in the North Sea, offshore UK. In this well, a thick Paleocene-Eocene interval is developed owing to uplift of the East Shetland Platform in the late Paleocene. Carbon isotope data through this well, coupled with detailed sedimentological analysis, show that the PETM interval is contemporaneous with &gt;200 sandstone turbidites layers. Mud deposition without turbidites dominated sedimentation below and above the PETM. These observations support previous work from other localities highlighting how climate warming during the PETM likely drove substantial changes in hydrological cycling, erosion and sediment supply. Spectral analysis of turbidite recurrence in the PETM interval suggests that the abundance of turbidites was modulated in part by ~21 kyr astronomical precession climate cycles, further emphasizing a potential climatic control on turbidite sedimentation. In detail, we note a kiloyear-scale time lag between onset of the PETM carbon isotope excursion and the appearance of turbidites in the succession, highlighting a delay between PETM carbon release and warming and the basin-wide response in sediment supply.&lt;/p&gt;

scholarly journals Sediment Supply Explains Long‐Term and Large‐Scale Patterns in Salt Marsh Lateral Expansion and Erosion

2019 ◽  
Vol 46 (20) ◽  
pp. 11178-11187 ◽  
Author(s):  
Cai J.T. Ladd ◽  
Mollie F. Duggan‐Edwards ◽  
Tjeerd J. Bouma ◽  
Jordi F. Pagès ◽  
Martin W. Skov
Keyword(s):  
Salt Marsh ◽  
Large Scale ◽  
Sediment Supply ◽  
Lateral Expansion

scholarly journals Large deep-sea zooplankton biomass mirrors primary production in the global ocean

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
S. Hernández-León ◽  
R. Koppelmann ◽  
E. Fraile-Nuez ◽  
A. Bode ◽  
C. Mompeán ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Primary Production ◽  
Deep Sea ◽  
Large Scale ◽  
Net Primary Production ◽  
Deep Ocean ◽  
Zooplankton Biomass ◽  
Global Ocean ◽  
Global Coupling ◽  
Do So

AbstractThe biological pump transports organic carbon produced by photosynthesis to the meso- and bathypelagic zones, the latter removing carbon from exchanging with the atmosphere over centennial time scales. Organisms living in both zones are supported by a passive flux of particles, and carbon transported to the deep-sea through vertical zooplankton migrations. Here we report globally-coherent positive relationships between zooplankton biomass in the epi-, meso-, and bathypelagic layers and average net primary production (NPP). We do so based on a global assessment of available deep-sea zooplankton biomass data and large-scale estimates of average NPP. The relationships obtained imply that increased NPP leads to enhanced transference of organic carbon to the deep ocean. Estimated remineralization from respiration rates by deep-sea zooplankton requires a minimum supply of 0.44 Pg C y−1 transported into the bathypelagic ocean, comparable to the passive carbon sequestration. We suggest that the global coupling between NPP and bathypelagic zooplankton biomass must be also supported by an active transport mechanism associated to vertical zooplankton migration.

scholarly journals Supplied Sediment Tracking for Bridge Collapse with Large-Scale Channel Migration

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1881
Author(s):  
Takuya Inoue ◽  
Jagriti Mishra ◽  
Kazuo Kato ◽  
Tamaki Sumner ◽  
Yasuyuki Shimizu
Keyword(s):  
Erosion Rate ◽  
Large Scale ◽  
Bank Erosion ◽  
Strong Relationship ◽  
Sediment Supply ◽  
Study Region ◽  
Flow Discharge ◽  
Bridge Abutment ◽  
Bridge Collapse ◽  
Flooding Events

Here, we provide a numerical model that assigns an identification number to trace sediments and also identify the source of sediment supply. We analyze the efficacy of our model by reproducing the reach-scale field observations from flooding events in 2010 and 2016 that affected Kyusen Bridge over the Bebetsu River, Hokkaido, Japan. Our simulation results can successfully reproduce and trace the formation of bars caused by sediment supply in the study region. Our study also suggests a strong relationship between bank erosion rate, sediment supply and flow-discharge. The bank erosion rate is higher when sediment supply increases, and bank erosion reduces as flow discharge goes down. The model can also replicate the changes in a bed concerning sediment supply and was used to reproduce the bridge-abutment failure caused by the 2016 flooding with large sediment supply and the bridge-pier failure caused by the 2010 flooding with less sediment supply.

scholarly journals Interannual variability of the northwestern Iberia deep ocean: Response to large-scale North Atlantic forcing

2015 ◽  
Vol 120 (2) ◽  
pp. 832-847 ◽  
Author(s):  
E. Prieto ◽  
C. González-Pola ◽  
A. Lavín ◽  
N. P. Holliday
Keyword(s):  
Interannual Variability ◽  
North Atlantic ◽  
Large Scale ◽  
Deep Ocean ◽  
Ocean Response

Abrupt transitions between gyroscopic and internal gravity waves: the mid-latitude case

2008 ◽  
Vol 598 ◽  
pp. 67-80 ◽  
Author(s):  
HANS VAN HAREN
Keyword(s):  
Large Scale ◽  
Deep Ocean ◽  
Internal Gravity Waves ◽  
Buoyancy Frequency ◽  
Neutral Stability ◽  
Density Profiles ◽  
Geostrophic Balance ◽  
Convective Mixing ◽  
Vertical Density ◽  
Wave Limit

The large-scale vertical density stratification, represented by buoyancy frequency N, is generally very stable in the upper half of the ocean, and relatively weak in the lower half. However, closer inspection of density profiles demonstrates steps rather than a smooth increase with depth. As is demonstrated here using Richardson number, geostrophic balance and slantwise convective mixing arguments, these layers have a limited set of minimum, weak stratification, N-values Nmin indicating the transition between stably stratified and convective ‘homogeneous’ layers. Adopting the viewpoint that the transition occurs for neutral stability in the direction of Earth's rotation Ω instead of gravity g, three discrete states are hypothesized for mid-latitudes: (i) Nmin = 2fh under linear stability conditions, (ii) Nmin = fh(|ϕ| < 45°) and (iii) Nmin = 4fh, both under nonlinear stability, where horizontal component fh = 2Ω cos ϕ at latitude ϕ. The Nmin are not in terms of inertial frequency f = 2Ω sin ϕ, because the effect of fh is the tilting of vortex tubes away from the local vertical in the direction of Ω. The above explains very well deep-ocean North-Atlantic and Mediterranean observations on transitions in conductivity-temperature with depth profiles, inertial polarization and near-inertial shear. The latter peaks at sub-inertial 0.97f, which is associated with the lower inertio-gravity wave limit for Nmin = 4fh, thereby stressing the importance of fh for the dominant physics associated with mixing in the ocean.

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