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TitreThe tropical connection between the Atlantic sector ice cores and the north pacific Mt Logan ice core
AuteurFisher, D A
SourceAmerican Geophysical Union, Fall Meeting 2009, abstracts; 2009 p. 1
Séries alt.Secteur des sciences de la Terre, Contribution externe 20100312
RéunionAmerican Geophysical Union Fall Meeting; San Francisco; US; décembre 14-18, 2009
Mediaen ligne; numérique
Lat/Long OENS-130.0000 -128.0000 62.0000 61.0000
Sujetsglace; échantillons de glace; épaisseurs des glaces; échantillons carrotés; concentration de glace; géologie des dépôts meubles/géomorphologie; géologie de l'environnement
ProgrammeÉtudes paléo-environnementales sur les changements climatiques, Géosciences de changements climatiques
LiensOnline - En ligne
Résumé(disponible en anglais seulement)
The stable isotope record from the Mt Logan, Yukon, Canada ice core spans the late Glacial to present and shows very large and sudden variations in O18 during the Holocene . It is hypothesized that they are driven by changes in the water sources ,which in turn, are determined by the state of ENSO. There seems to be no correlations between the Logan ice core isotope record and those from the North Atlantic (Greenland and Eastern Canadian Arctic). Using the stacked and co-dated Greenland and Eastern Canadian Arctic ice core records from the Holocene, it is possible to reproduce the Logan isotope record by subtracting the stacked Atlantic record from itself with an 1100 year lag. The correlations obtainable are -0.43 for 50 year average series. This correlation is significant at the 99.8 % level . The 1100 lag has also been found in previous studies comparing the Greenland to Antarctic ice cores (Stocker and Johnsen,2003). It is argued that such a lagged difference series is a proxy for the difference between the ocean water surface and deep temperatures in the tropical Pacific . ENSO’s amplitude is driven by this temperature difference, (Sun 2000). When the deep water is too warm, then the difference is too small to produce ENSO oscillations and strong tropical easterly winds persist (ie strong and constant La Nina). The ice core records from Mt Logan , Greenland and Eastern Arctic Canada all point to a similar history of ENSO oscillation strength. Prior to ~ 4200 BP the strong and constant La Nina tended to drive the tropical Pacific winds and moisture across to produce strong and reliable monsoons. Since 4200 BP the “modern” and variable pattern has been in place. There was a smaller scale shift about 1840 AD . For about a couple of centuries prior to 1840 AD , La Nina was in charge and after there were the oscillations that are thought of as normal. If the 1100 year lag between surface and bottom temperatures is true and if the bottom temperatures are echoes those from the N Atlantic 1100 years ago, there are implications for what we could expect from the tropical Pacific oscillations (ENSO) in the future.