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| Dolven, Jk; Cortese, G; Bjorklund, Kr. |
| Polycystine radiolarians are used to reconstruct summer sea surface temperatures (SSSTs) for the Late Pleistocene-Holocene (600-13,400 C-14 years BP) in the Norwegian Sea. At 13,200 C-14 years BP, the SSST was close to the average Holocene SSST (similar to12degreesC). It then gradually dropped to 7.1degreesC in the Younger Dryas. Near the Younger Dryas-Holocene transition (similar to10,000 C-14 years BP), the SSST increased 5degreesC in about 530 years. Four abrupt cooling events, with temperature drops of up to 2.1degreesC, are recognized during the Holocene: at 9340, 7100 ("8200 calendar years event''), 6400 and 1650 C-14 years BP. Radiolarian SSSTs and the isotopic signal from the GISP2 ice core are strongly coupled, stressing the importance of the... |
| Tipo: Text |
Palavras-chave: Radiolarians; Paleoclimate; Late Pleistocene-Holocene; Norwegian Sea. |
| Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00223/33384/31894.pdf |
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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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| Cortese, G; Dolven, Jk; Bjorklund, Kr; Malmgren, Ba. |
| Artificial Neural Networks (ANN) were trained by using an extensive radiolarian census dataset from the Nordic (Greenland, Norwegian, and Iceland) Seas. The regressions between observed and predicted Summer Sea Temperature (SST) indicate that lower error margins and better correlation coefficients are obtained for 100 m (SST100) compared to 10 m (SST10) water depth, and by using a subset of species instead of all species. The trained ANNs were subsequently applied to radiolarian data from two Norwegian Sea cores, HM 79-4 and MD95-2011, for reconstructions of SSTs through the last 15,000 years. The reconstructed SST is quite high during the Bolling-Allerod, when it reaches values only found later during the warmest phase of the Holocene. The climatic... |
| Tipo: Text |
Palavras-chave: Artificial neural networks; Radiolarians; Nordic seas; Late Pleistocene; Holocene. |
| Ano: 2005 |
URL: https://archimer.ifremer.fr/doc/00229/34074/32535.pdf |
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