Caractérisation de la variabilité climatique Holocène à partir de séries continentales, marines et glaciaires
The aim of this thesis is to characterize Holocene climate variability (10 000-0 years) by the analysis of marine, continental and glacial records. North and South Atlantic and southern ocean records allowed to identify two millenial frequencies. The first are present during the first part of the Ho...
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Other Authors: | , , , , |
Format: | Doctoral or Postdoctoral Thesis |
Language: | French |
Published: |
HAL CCSD
2008
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Subjects: | |
Online Access: | https://theses.hal.science/tel-00535769 https://theses.hal.science/tel-00535769/document https://theses.hal.science/tel-00535769/file/These_Debret_2008.pdf |
Summary: | The aim of this thesis is to characterize Holocene climate variability (10 000-0 years) by the analysis of marine, continental and glacial records. North and South Atlantic and southern ocean records allowed to identify two millenial frequencies. The first are present during the first part of the Holocene (10 000-5 000 years) and are comparable to frequencies observed in solar activity, whereas the second ones, during the late Holocene (5 000-10 000 years), suggest an internal oceanic forcing. This Holocene pattern depicts an oceanic circulation influenced by the melt water coming from the last continental ice sheet in North America until 5 000 years. After 5 000 years, the second part of the Holocene is marked by the gradual appearance of internal forcing, accompanied by a stabilisation of the signal linked to a less disturbed salinity content. In Antarctica, original dust data were produced for the last 2 000 years from the Vostok and Dôme C ice cores. For Holocene period, the analysis of various data (stable isotope, Deuterium excess, Dust) from different places in East Antarctica does not yield persistent and significant feature for all of this proxies. In Greenland, the only significant frequencies in the Deuterium content are the results of a huge melt water discharge events around 8 200 years. The climatic signal extracted from polar ice caps for the Holocene period is hidden by specific processes such as local effects, proxy sensitivity,. L'objectif de la thèse est de caractériser la variabilité climatique de la période Holocène (10 000-0 ans) en analysant des séries climatiques d'enregistrements marins, continentaux, glaciaires. Les enregistrements d'Atlantique Nord et Sud ainsi que l'océan Austral ont permis d'identifier deux types de fréquences millénaires : les premières s'expriment pendant le début de l'Holocène (10 000-5 000 BP) et sont similaires aux fréquences solaires, les secondes, pendant la fin de l'Holocène, suggèrent un forçage interne océanique. Ce schéma Holocène avec une circulation ... |
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