1250 Years of Global Volcanism as Revealed by Central Greenland Ice Cores

Clausen, H. B.; Hammer, C. U.; Christensen, Jonas; Hvidberg, Christine S.; Dahl-Jensen, Dorthe; Legrand, Michel; Steffensen, Jørgen Peder

doi:10.1007/978-3-642-51172-1_9

Cited by 36 publications

(31 citation statements)

References 23 publications

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“…The unidentified 1516-event must be 'local', because, although it is the largest sulfate concentration peak in the last 550 years in the PRCol and Eclipse cores (Yalcin et al, 2007), it has no prominence in the eastern Arctic ice cores (Clausen et al, 1995;Zheng et al, 1998). The White River candidate peak is within a metre of where it is expected.…”

Section: Timescale For Prcol Logan Holocenementioning

confidence: 96%

The Mt Logan Holocene—late Wisconsinan isotope record: tropical Pacific—Yukon connections

et al. 2008

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The ice core recovered from Prospector Russell Col on Mt Logan (5.4 km a.s.l.), in the Yukon spans over 20 000 years. This unique record offers a Pacific view of the stable isotope and chemical record from the Lateglacial to the present. The timescale is based on seasonal counted years, the largest known volcanic acid signatures and the major shift in stable isotopes and chemistry at the end of the Younger Dryas. There are large and sustained changes in the stable isotopic record that are anti-correlated with marine and continental chemistry series. The oxygen-18 in this area is not a proxy for palaeotemperature but rather for source region. The last major isotope shift in AD 1840 in δ( 18 O) and chemistry is compared with the Quinn's ENSO record. During periods of more frequent La Niña (stronger tropical easterlies) there is more zonal flow of water vapour transport to the Pacific Northwest, δ( 18 O) values are larger and the deuterium excess d smaller. These periods coincide with periods of lower accumulation/precipitation in southern Yukon. The Holocene δ( 18 O) record indicates many large shifts between the meridional (strong El Niño) and zonal (La Niña). Comparison of the Logan isotopic record and the moisture/temperature-sensitive time series of peat bog inception dates for the Northwest shows a strong correlation (0.36) that points to high accumulation rates coincident with low δ( 18 O) and enhanced meridional flow. Major changes in the core at 4200 BP and 7000-8000 BP point to enhanced meridional flow, which coincide with big changes in the Pacific palaeorecords of the balance between El Niño and La Niña. 4200 BP seems to have inaugurated the 'modern' ENSO world.

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Section: Timescale For Prcol Logan Holocenementioning

confidence: 96%

The Mt Logan Holocene—late Wisconsinan isotope record: tropical Pacific—Yukon connections

et al. 2008

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“…The PRCol record is placed on a time scale using a model, recent accumulation rates and the major ECM (acid) peaks of Katmai, Laki, a large unknown peak at A.D. 1516 and White River (Clausen et al, 1995;Clague et al, 1995;Zheng et al, 1998;Yalcin and Wake, 2003). The unidentified A.D. 1516 event must be "local" because, although it is the largest peak in the last 550 years, it has no prominence in the Eastern Arctic (Clausen et al, 1995;Zheng et al, 1998). Between the fixed points of this time scale, the uncertainty could be ±3 years.…”

Section: Résumé Comportement Des Isotopes Stables Dans Les Carottes Dmentioning

confidence: 99%

Stable Isotope Records from Mount Logan, Eclipse Ice Cores and Nearby Jellybean Lake. Water Cycle of the North Pacific Over 2000 Years and Over Five Vertical Kilometres: Sudden Shifts and Tropical Connections

Fisher

Wake

Kreutz

et al. 2006

gpq

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140

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Three ice cores recovered on or near Mount Logan, together with a nearby lake record (Jellybean Lake), cover variously 500 to 30 000 years. This suite of records offers a unique view of the lapse rate in stable isotopes from the lower to upper troposphere. The region is climatologically important, being beside the Cordilleran pinning-point of the Rossby Wave system and the Aleutian Low. Comparison of stable isotope series over the last 2000 years and model simulations suggest sudden and persistent shifts between modern (mixed) and zonal flow regimes of water vapour transport to the Pacific Northwest. The last such shift was in A.D. 1840. Model simulations for modern and “pure” zonal flow suggest that these shifts are consistent regime changes between these flow types, with predominantly zonal flow prior to ca. A.D. 1840 and modern thereafter. The 5.4 and 0.8 km asl records show a shift at A.D. 1840 and another at A.D. 800. It is speculated that the A.D. 1840 regime shift coincided with the end of the Little Ice Age and the A.D. 800 shift with the beginning of the European Medieval Warm Period. The shifts are very abrupt, taking only a few years at most.Trois carottes de glace prélevées à proximité du mont Logan, combinées à une coupe stratigraphique du lac Jellybean, couvrent une période comprise entre 500 et 30 000 ans. Elles renseignent sur les taux de changement de la composition isotopique de la troposphère. La région étudiée est importante au niveau climatologique puisqu’elle est au point de convergence des ondes de Rossby et de la dépression des Aléoutiennes. La comparaison entre la composition isotopique depuis 2000 ans et les résultats des simulations suggère des changements brusques et persistants entre les régimes de transport de vapeur d’eau modernes et zonaux dans le nord-est du Pacifique, où le dernier changement s’est produit en 1840 de notre ère. Les simulations indiquent que les changements de flux correspondent aux changements de régime, avec un flux zonal avant ca 1840 pour passer au type moderne ensuite. Les forages à 5,4 et 0,8 km d’altitude montrent un changement en A.D. 1840 et un autre en l’an 800. On présume que ces changements de régime coïncident respectivement avec la fin du Petit Âge Glaciaire et le début de la période médiévale chaude, ces changements s’étant produits en quelques années seulement

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“…We used the electrical conductivity data from the GRIP core [Clausen et al, 1995] to estimate the imaginary part of the complex permittivity required for our simulation. We assumed that the permittivity is constant as a function of depth for our simulations.…”

Section: Simulationmentioning

confidence: 99%

High‐resolution radar mapping of internal layers at the North Greenland Ice Core Project

Kanagaratnam¹,

Gogineni²,

Gundestrup³

et al. 2001

J. Geophys. Res.

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Abstract. Existing accumulation maps with reported errors of about 20% are determined from sparsely distributed ice cores and pits. A more accurate accumulation rate might be obtained by generating continuous profiles of dated layers from high-resolution radar mapping of near-surface internal layers in the ice sheet (isochrones). To generate such profiles we designed and developed an ultrawideband radar for high-resolution mapping of internal layers in the top 200 m of ice and tested it at the North Greenland Ice Core Project drill site. Reflection profiles of 2-and 10-km length reveal horizons that we correlate with electrical conductivity measurement (ECM) recordings. Our results show that the radar-determined depth of internal layers is within _+2 m of that in an ice core collected at a nearby location. Preliminary frequency analyses of layer reflections reveal that the reflections are strongest at the 500-1000 MHz frequency range. Long-term accumulation rate computed from radar data is within 5% of that obtained from snow pits.

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1250 Years of Global Volcanism as Revealed by Central Greenland Ice Cores

Cited by 36 publications

References 23 publications

The Mt Logan Holocene—late Wisconsinan isotope record: tropical Pacific—Yukon connections

The Mt Logan Holocene—late Wisconsinan isotope record: tropical Pacific—Yukon connections

Stable Isotope Records from Mount Logan, Eclipse Ice Cores and Nearby Jellybean Lake. Water Cycle of the North Pacific Over 2000 Years and Over Five Vertical Kilometres: Sudden Shifts and Tropical Connections

High‐resolution radar mapping of internal layers at the North Greenland Ice Core Project

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