Consulta: subjectFacets:"Deglacial"
Registros recuperados: 6
Data/hora: 02/06/2024 15:47:42

Coherent Response of Antarctic Intermediate Water and Atlantic Meridional Overturning Circulation During the Last Deglaciation: Reconciling Contrasting Neodymium Isotope Reconstructions From the Tropical Atlantic
Provedor de dados: 5
Autores: Gu, Sifan; Liu, Zhengyu; Zhang, Jiaxu; Rempfer, Johannes; Joos, Fortunat; Oppo, Delia W.
Antarctic Intermediate Water (AAIW) plays important roles in the global climate system and the global ocean nutrient and carbon cycles. However, it is unclear how AAIW responds to global climate changes. In particular, neodymium isotopic composition (epsilon(Nd)) reconstructions from different locations from the tropical Atlantic have led to a debate on the relationship between northward penetration of AAIW into the tropical Atlantic and the Atlantic meridional overturning circulation (AMOC) variability during the last deglaciation. We resolve this controversy by studying the transient oceanic evolution during the last deglaciation using a neodymium-enabled ocean model. Our results suggest a coherent response of AAIW and AMOC: when AMOC weakens, the...
Tipo: Text
Palavras-chave: AAIW; AMOC; Deglacial; Neodymium isotope; Paleocirculation tracer.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00495/60709/65334.pdf

Impact of deglacial and Holocene AMOC changes on the mixed layer and deepwater hydrography of the subtropical North Atlantic
Provedor de dados: 5
Autores: Respschläger, Janne.
The Atlantic meridional overturning circulation (AMOC) transports warm saline water from low to high northern latitudes where it cools, sinks down and returns southward as deepwater flow. By the heat transfer from low to high latitudes, AMOC contributes in balancing the global energy budget and thus is an important part of global climate system. Within this study the impact of AMOC changes on surface and deepwater hydrography of the subtropical North Atlantic is investigated by the use of high-resolution sediment cores from a coring site located south of the Azores at the eastern flank of the Mid Atlantic Ridge. The Azores coring site is situated in the subtropical eastern North Atlantic (NA) at the boundary between warm Subtropical Gyre Water (STG) and...
Tipo: Text
Palavras-chave: Paleoceanography; AMOC; Subtropical gyre; Deglacial; Multiproxy SST; BWT; Stable isotopes; Planktonic and benthic foraminifera.
Ano: 2013
URL: https://archimer.ifremer.fr/doc/00493/60444/63889.pdf

Ocean Temperature Variability during the Late Pleistocene
Provedor de dados: 5
Autores: Hoffman, Jeremy Scott.
This dissertation explores one overarching question relevant to the paleoclimate of the latest Pleistocene glacial cycle (approximately the last 130,000 years): “How did spatial and temporal evolution of ocean temperature, both at the surface and interior, relate to other parts of the climate system in the late Pleistocene?” Results from three studies are presented that seek to address longstanding questions in paleoceanography and paleoclimatology for the late Pleistocene using a combination of novel and accepted statistical and geochemical analysis techniques and leveraging comparisons with available global climate model data. The last interglaciation (LIG; ~129-116 ka) was the most recent period in Earth’s history with higher-than-present global sea...
Tipo: Text
Palavras-chave: Paleoclimate; Interglacial; Heinrich events; Deglacial; Paleoceanography; Climate.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00505/61702/65670.pdf

Late Quaternary changes in intermediate water oxygenation and oxygen minimum zone, northern Japan: A benthic foraminiferal perspective
Provedor de dados: 5
Autores: Shibahara, Akihiko; Ohkushi, Ken'Ichi; Kennett, James P.; Ikehara, Ken.
A strong oxygen minimum zone (OMZ) currently exists at upper intermediate water depths on the northern Japanese margin, NW Pacific. The OMZ results largely from a combination of high surface water productivity and poor ventilation of upper intermediate waters. We investigated late Quaternary history ( last 34 kyr) of ocean floor oxygenation and the OMZ using quantitative changes in benthic foraminiferal assemblages in three sediment cores taken from the continental slope off Shimokita Peninsula and Tokachi, northern Japan, at water depths between 975 and 1363 m. These cores are well located within the present-day OMZ, a region of high surface water productivity, and in close proximity to the source region of North Pacific Intermediate Water. Late...
Tipo: Text
Palavras-chave: Benthic foraminifera; Paleoceanography; Oyashio; Biological production; Last glacial; Deglacial; Holocene.
Ano: 2007
URL: https://archimer.ifremer.fr/doc/00236/34733/33182.pdf

Atlantic Meridional Overturning Circulation during the Last Glacial and Deglacial: Inferences from the Atlantic Tropical Thermocline Temperature and Seawater Radiocarbon Activity
Provedor de dados: 5
Autores: Huang, Enqing.
This thesis aims to investigate variations of the last glacial and deglacial Atlantic Ocean circulation, with emphasize on the Atlantic deepwater ventilation rate during the Last Glacial Maximum (LGM). The highlights of the thesis are as the followings: (1) the modern frontal zone between the North Atlantic and the South Atlantic central waters off NW Africa shifted to the south during the last glacial and deglacial time periods. (2) The radiocarbon-based circulation age of the deep Atlantic (&gt; 1500 m) was estimated to be less than 400 years during the LGM, which was equal to or less than its pre-bomb value. Therefore, the LGM deep Atlantic was inferred to be well ventilated. (3) The abyssal Atlantic (below 2500 m) prior to the LGM was more depleted in...
Tipo: Text
Palavras-chave: Climate change; Ocean circulation; Atlantic Ocean; Glacial; Deglacial; Thermocline; Radiocarbon; Global carbon cycle; Foraminifera; Carbonate; Trace elements; Deep ocean ventilation rates.
Ano: 2013
URL: https://archimer.ifremer.fr/doc/00493/60446/63891.pdf

Late Glacial to Preboreal sea-level rise recorded by the Rhone deltaic system (NW Mediterranean)
Provedor de dados: 5
Autores: Berne, Serge; Jouet, Gwenael; Bassetti, Maria-angela; Dennielou, Bernard; Taviani, M.
A unique late Glacial-Preboreal record of changes in sea-level and sediment fluxes originating from the Alps is recorded in the Rhone subaqueous delta in the Western Mediterranean Sea. The compilation of detailed bathymetric charts, together with high-resolution seismic profiles and long cores, reveals the detailed architecture of several sediment lobes, related to periods of decreased sea-level rise and/or increased sediment flux. They are situated along the retreat path of the Rhone distributaries, from the shelf edge and canyon heads up to the modem coastline. They form transgressive backstepping parasequences across the shelf, the late Holocene (highstand) deltas being confined to the inner shelf The most prominent feature is an elongated...
Tipo: Text
Palavras-chave: Western Mediterranean sea; Delta; Younger Dryas; Deglacial; Sea level.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-3589.pdf