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| Cortese, G; Abelmann, A; Gersonde, R. |
| ODP Site 1089 is optimally located in order to monitor the occurrence of maxima in Agulhas heat and salt spillage from the Indian to the Atlantic Ocean. Radiolarian-based paleotemperature transfer functions allowed to reconstruct the climatic history for the last 450 kyr at this location. A warm sea surface temperature anomaly during Marine Isotope Stage (MIS) 10 was recognized and traced to other oceanic records along the surface branch of the global thermolialine (THC) circulation system, and is particularly marked at locations where a strong interaction between oceanic and atmospheric overturning cells and fronts occurs. This anomaly is absent in the Vostok ice core deuterium, and in oceanic records from the Antarctic Zone. However, it is present in the... |
| Tipo: Text |
Palavras-chave: Agulhas; Paleotemperature; Radiolarians; South Atlantic. |
| Ano: 2004 |
URL: https://archimer.ifremer.fr/doc/00229/34028/32422.pdf |
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| Sicre, Ma; Bard, E; Ezat, U; Rostek, F. |
| The C(37)-C(39) alkenones were quantified in suspended particulate matter obtained from the surface waters of the North Atlantic, including the Nordic seas, over a temperature range of 4degrees20 C. U(37)(K') values were linearly correlated to temperature over the entire range covered by our data set, i.e., 420 C (U(37)(K') = 0.027T + 0.036, r(2) = 0.97). The compilation of water column data from the Atlantic, Pacific, and Southern Ocean and Mediterranean Sea suggests that the linear model may not be the best function for fitting U(37)(K') and in situ temperature values. It also shows that suspended matter data from warm waters (T >20degreesC) are still needed to constrain the equation of the global curve. High abundances of C(37: 4) were found in the... |
| Tipo: Text |
Palavras-chave: Alkenones; Paleotemperature; Calibration; Atlantic Ocean; Plankton; Geochemistry; Marine geochemistry; Global change; Biogeochemical processes (4805); Oceanography; Paleoceanography. |
| Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00223/33393/31866.pdf |
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| Rasmussen, Tine L.; Thomsen, Erik. |
| The last deglaciation, 20,000–10,000 years ago, was a period of global warming and rapidly shrinking ice sheets. It was also climatically unstable and retreats were interrupted by re-advances. Retreat rates and timing relative to climatic changes have therefore been difficult to establish. We here study a suite of 12 marine sediment cores from Storfjorden and Storfjorden Trough, Svalbard. The purpose is to reconstruct retreat patterns and retreat rates of a high northern latitude marine-based ice stream from the Svalbard-Barents Sea Ice Sheet in relation to paleoceanographic and paleoclimatic changes. The study is based on abundance and composition of planktic and benthic foraminiferal assemblages, ice rafted debris (IRD), lithology, and 70 AMS-14C dates.... |
| Tipo: Text |
Palavras-chave: Ice retreat rates; Storfjorden ice stream; Paleoceanography; Paleoclimate; Paleotemperature. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00658/77019/78289.pdf |
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| Yamamoto, Yasuto; Ajioka, Taku; Yamamoto, Masanobu. |
| We investigated branched and isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs) in surface soils and a paleosol sequence to understand the effects of environmental and postdepositional factors on branched GDGT composition in different soil types and to reconstruct the past changes in the mean annual air temperature (MAAT) in southwestern Japan during the last 15 ka. The estimated MAAT was overestimated by 6 degrees C and 2 degrees C when the global and regional soil calibrations were applied, respectively. Additionally, the estimated MAAT increased downward by a maximum of 4 degrees C in the upper 30 cm of the soil sequence. This is likely to reflect the addition of newly produced branched GDGTs in subsurface soils. The estimated MAATs in a paleosol... |
| Tipo: Text |
Palavras-chave: GDGT; MBT/CBT; Paleotemperature; Japan; Holocene. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00421/53259/54690.pdf |
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| Ujiie, Yurika; Asahi, Hirofumi; Sagawa, Takuya; Bassinot, Franck. |
| The North Pacific Subtropical Gyre (NPSG) has two important functions, i.e., one in ocean heat transfer and another as a driving force for circulation of the surface and intermediate waters on the basin scale. In the present study, we describe records of the vertical thermal structures and distributions of water masses in the upper ocean of the subtropical northwest (NW) Pacific for the past 190 kyr, using two sediment cores collected from the Kuroshio Current area in the East China Sea and the NPSG area. During the two glacial periods, the Kuroshio Current was weakened owing to changes in ocean-atmosphere circulation and eustasy. The differences in the Mg/Ca-derived temperatures between surface and thermocline waters show the changes of depth and... |
| Tipo: Text |
Palavras-chave: North Pacific Subtropical Gyre; LGM; MIS 6; Paleotemperature; Water-column structure. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00358/46911/46812.pdf |
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| Cortese, G.; Abelmann, A.; Gersonde, R.. |
| A submillennial resolution, radiolarian-based record of summer sea surface temperature (SST) documents the last five glacial to interglacial transitions at the subtropical front, southern Atlantic Ocean. Rapid fluctuations occur both during glacial and interglacial intervals, and sudden cooling episodes at glacial terminations are recurrent. Surface hydrography and global ice volume proxies from the same core suggest that summer SST increases prior to terminations lead global ice- volume decreases by 4.7 +/- 3.7 ka (in the eccentricity band), 6.9 +/- 2.5 ka (obliquity), and 2.7 +/- 0.9 ka (precession). A comparison between SST and benthic delta C-13 suggests a decoupling in the response of northern subantarctic surface, intermediate, and deep water masses... |
| Tipo: Text |
Palavras-chave: Paleotemperature; Radiolaria; Southern Ocean. |
| Ano: 2007 |
URL: https://archimer.ifremer.fr/doc/00236/34725/33297.pdf |
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