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Author |
Alexander, B.; Savarino, J.; Kreutz, K.J.; Thiemens, M.H. |
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Title |
Impact of preindustrial biomass-burning emissions on the oxidation pathways of tropospheric sulfur and nitrogen |
Type |
Journal Article |
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Year |
2004 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
109 |
Issue |
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Pages |
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Keywords |
0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry; 1040 Geochemistry: Isotopic composition/chemistry; 1610 Global Change: Atmosphere |
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Abstract |
Ice core measurements (H2O2 and CH4/HCHO) and modeling studies indicate a change in the oxidation capacity of the atmosphere since the onset of the Industrial Revolution due to increases in fossil fuel burning emissions [e.g., Lelieveld et al., 2002; Hauglustaine and Brasseur, 2001; Wang and Jacob, 1998; Staffelbach et al., 1991]. The mass-independent fractionation (MIF) in the oxygen isotopes of sulfate and nitrate from a Greenland ice core reveal that biomass-burning events in North America just prior to the Industrial Revolution significantly impacted the oxidation pathways of sulfur and nitrogen species deposited in Greenland ice. This finding highlights the importance of biomass-burning emissions for atmospheric chemistry in preindustrial North America and warrants the inclusion of this impact in modeling studies estimating changes in atmospheric oxidant chemistry since the Industrial Revolution, particularly when using paleo-oxidant data as a reference for model evaluation. |
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1011 |
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American Geophysical Union |
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ISSN |
0148-0227 |
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yes |
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Call Number  |
IPEV @ Thierry.Lemaire @ |
Serial |
5555 |
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Author |
Alexander, B.; Park, R.J.; Jacob, D.J.; Li, Q.B.; Yantosca, R.M.; Savarino, J.; Lee, C.C.W.; Thiemens, M.H. |
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Title |
Sulfate formation in sea-salt aerosols: Constraints from oxygen isotopes |
Type |
Journal Article |
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Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
110 |
Issue |
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Pages |
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Keywords |
atmospheric chemistry; aerosol formation; isotopes; 0305 Atmospheric Composition and Structure: Aerosols and particles; 0312 Atmospheric Composition and Structure: Air/sea constituent fluxes; 0365 Atmospheric Composition and Structure: Troposphere: composition and chemistry; 0490 Biogeosciences: Trace gases; 1041 Geochemistry: Stable isotope geochemistry |
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Abstract |
We use observations of the mass-independent oxygen isotopic composition (?17O) of sulfate in the marine boundary layer (MBL) to quantify the sulfate source from aqueous SO2 (S(IV)) oxidation by O3 in alkaline sea-salt aerosols. Oxidation by O3 imparts a large ?17O signature to the resulting sulfate (8.8‰) relative to oxidation by H2O2 (0.9‰) or by OH or O2 (0‰). Ship data from two Indian Ocean Experiment (INDOEX) cruises in the Indian Ocean indicate ?17O values usually <1‰ in the submicron sulfate aerosol but considerable variability in the supermicron sulfate with frequent occurrences above 1‰ and up to 6.7‰. The large ?17O values are associated with high concentrations of sea-salt aerosols, providing evidence for the S(IV) + O3 pathway. We use a global chemical transport model (GEOS-CHEM) to interpret quantitatively the INDOEX observations and to assess the global importance of sulfate production in sea-salt aerosols. The model accounts for titration of sea-salt alkalinity in the MBL by uptake of acid gases (SO2, H2SO4, and HNO3), shutting down the S(IV) + O3 pathway. We find that this titration occurs rapidly over much of the oceans except at high latitudes (strong sea-salt emission) and is due to both the S(IV) + O3 reaction and HNO3 (g) condensation; that is, sulfate formation in sea-salt aerosols is limited by the alkalinity flux from the ocean and by competition for this alkalinity supply from HNO3 (g). The model is consistent with the ?17O magnitudes and patterns in the INDOEX data. Titration of alkalinity is critical for the success of the model simulation. Regeneration of sea-salt aerosol alkalinity by OH uptake is inconsistent with the ?17O observations in INDOEX. Model results indicate that sulfate production in sea-salt aerosols decreases MBL SO2 concentrations and gas phase H2SO4 production rates by typically 10–30% (up to >70%) and increases MBL sulfate concentrations by typically >10% (up to 30%). Globally, this mechanism contributes 9% of atmospheric sulfate production and 1% of the sulfate burden. The impact on H2SO4 (g) formation and implications for the potential formation of new particles in the MBL warrants inclusion in models examining the radiative effects of sulfate aerosols. |
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399 |
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American Geophysical Union |
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ISSN |
0148-0227 |
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yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5554 |
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Author |
Nishitani, N.; Ogawa, T.; Sato, N.; Yamagishi, H.; Pinnock, M.; Villain, J.-P.; Sofko, G.; Troshichev, O. |
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Title |
A study of the dusk convection cell's response to an IMF southward turning |
Type |
Journal Article |
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Year |
2002 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
107 |
Issue |
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Pages |
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Keywords |
2463 Ionosphere: Plasma convection; 2431 Ionosphere: Ionosphere/magnetosphere interactions; 2437 Ionosphere: Ionospheric dynamics; 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions |
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Abstract |
One example of the response of ionospheric convection and the polar cap boundary to a sudden change in the interplanetary magnetic field (IMF) orientation has been studied by using ground magnetometers, the Super Dual Auroral Radar Network (SuperDARN), and Defense Meteorological Satellite Program (DMSP) particle detectors when the IMF suddenly changed from northward (+6 nT) to strongly southward (?19 nT) at 1716 UT on 5 September 1995. The Bz component was fairly constant for ?2 hours before and ?25 min after the sudden IMF change. The convection flow changed almost simultaneously over a global extent. This initial change of the convection pattern can be characterized by a sudden formation of a large flow vortex in the afternoon sector. This agrees with the earlier findings by Ruohoniemi and Greenwald [1998] and Ridley et al. [1998]. On the other hand, the response of the polar cap boundary (or its proxy) is more complicated. The Saskatoon radar, located in the late morning sector, observed an equatorward shift of the cusp scatter region simultaneously with the initial response of the convection flows. The DMSP particle data also showed a simultaneous equatorward expansion of the auroral oval in the 2100 magnetic local time (MLT) sector. The radar and particle data indicate the immediate equatorward expansion of the precipitation regions in the noon and premidnight sectors. About 10–20 min after the initial change, there were changes observed in the dusk region, namely, an equatorward expansion of the current reversal boundary observed by the Greenland magnetometer chain in the dusk sector between 1740 and 1750 UT and an equatorward expansion of the convection reversal boundary detected by the Stokkseyri, Halley, and Syowa radars. The delayed responses were observed 18-8 min before a substorm onset was recorded at midlatitude stations at 1756 UT. These observations indicate that there were two kinds of ionospheric responses to the southward turning of the IMF; the first response is the formation of the convection vortex and the equatorward shift of the polar cap boundary at noon and at ?2100 MLT, and the second response is the equatorward expansion of the convection reversal boundary in the dusk sector. We make the case that the first response is associated with the propagation of magnetosonic waves and that the second response is consistent with the Cowley and Lockwood [1992] picture of the redistribution of the newly created open flux in the polar cap region. |
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Programme |
312;911 |
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Thesis |
Bachelor's thesis |
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Publisher |
American Geophysical Union |
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ISSN |
0148-0227 |
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Approved |
yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5557 |
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Author |
Dominé, F.; Rey-Hanot, L. |
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Title |
Adsorption isotherms of acetone on ice between 193 and 213 K |
Type |
Journal Article |
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Year |
2002 |
Publication |
Geophysical research letters |
Abbreviated Journal |
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Volume |
29 |
Issue |
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Pages |
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Keywords |
1863 Hydrology: Snow and ice; 3947 Mineral Physics: Surfaces and interfaces; 0320 Atmospheric Composition and Structure: Cloud physics and chemistry |
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Abstract |
The adsorption isotherms of acetone on ice were measured at 193, 203 and 213 K using a volumetric method with mass spectrometric detection. Henry's law applies for values of the acetone partial pressure, Pacetone, lower than 10?3 Pa. Where Henry's law applies, the number of acetone molecules adsorbed per cm2 of ice, is: nads = 90.53 × Pacetone × exp (6610.2/T), with Pacetone in Pa and T in K. The measured enthalpy of adsorption of acetone on ice is ?Hads = ?55±7 kJ/mol. Acetone values previously measured in Arctic snow are too high to be due to adsorbed acetone. Acetone was then probably dissolved in ice or in organic aerosols contained in snow. Adsorption of acetone in the snowpack or on ice crystals in cirrus clouds is insufficient to affect Pacetone above the snow or in the clouds. |
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Programme |
437 |
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American Geophysical Union |
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ISSN |
0094-8276 |
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yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5560 |
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Author |
Convey, P.; Frenot, Y.; Gremmen, N.; Bergstrom, D. |
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Title |
Biological Invasions |
Type |
Book Chapter |
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Year |
2006 |
Publication |
Trends in Antarctic Terrestrial and Limnetic Ecosystems |
Abbreviated Journal |
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Pages |
193-220 |
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Programme |
136 |
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yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5561 |
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Author |
Weimerskirch, H.; Cherel, Y.; Cuenot-Chaillet, F.; Ridoux, V. |
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Title |
Alternative foraging strategies and resource allocation by male and female wandering albatrosses. |
Type |
Journal Article |
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Year |
1997 |
Publication |
Ecology |
Abbreviated Journal |
Ecology |
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Volume |
78 |
Issue |
7 |
Pages |
2051-2063 |
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Programme |
109 |
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ISSN |
0012-9658 |
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yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5562 |
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Author |
Hennion, F.; Huiskes, A.; Robinson, S.; Convey, P. |
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Title |
Physiological Traits of Organisms in a Changing Environment |
Type |
Book Chapter |
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Year |
2006 |
Publication |
Trends in Antarctic Terrestrial and Limnetic Ecosystems |
Abbreviated Journal |
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Volume |
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Pages |
129-159 |
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Programme |
136 |
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Approved |
yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5563 |
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Author |
Simon, N.S.C.; Neumann, E.-R.; Bonadiman, C.; Coltorti, M.; Delpech, G.; Gregoire, M.; Widom, E. |
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Title |
Ultra-refractory Domains in the Oceanic Mantle Lithosphere Sampled as Mantle Xenoliths at Ocean Islands |
Type |
Journal Article |
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Year |
2008 |
Publication |
Journal of petrology |
Abbreviated Journal |
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Volume |
49 |
Issue |
6 |
Pages |
1223-1251 |
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Abstract |
Many peridotite xenoliths sampled at ocean islands appear to have strongly refractory major element and modal compositions. To better constrain the chemistry, abundance and origin of these ultra-refractory rocks we compiled a large number of data for xenoliths from nine groups of ocean islands. The xenoliths were filtered petrographically for signs of melt infiltration and modal metasomatism, and the samples affected by these processes were excluded. The xenolith suites from most ocean islands are dominated by ultra-refractory harzburgites. Exceptions are the Hawaii and Tahiti peridotites, which are more fertile and contain primary clinopyroxene, and the Cape Verde suite, which contains both ultra-refractory and more fertile xenoliths. Ultra-refractory harzburgites are characterized by the absence of primary clinopyroxene, low whole-rock Al2O3, CaO, FeO/MgO and heavy rare earth element (HREE) concentrations, low Al2O3 in orthopyroxene (generally < 3 wt %), high Cr-number in spinel (0{middle dot}3-0{middle dot}8) and high forsterite contents in olivine (averages > 91{middle dot}5). They are therefore on average significantly more refractory than peridotites dredged and drilled from mid-ocean ridges and fracture zones. Moreover, their compositions resemble those of oceanic forearc peridotites. The formation of ultra-refractory ocean island harzburgites requires potential temperatures above those normally observed at modern mid-ocean ridges, and/or fluid fluxed conditions. Some ultra-refractory ocean island harzburgites give high Os model ages (up to 3300 Ma), showing that their formation significantly pre-dates the oceanic crust in the area. A genetic relationship with the host plume is considered unlikely based on textural observations, equilibration temperatures and pressures, inferred physical properties, and the long-term depleted Os and Sr isotope compositions of some of the harzburgites. Although we do not exclude the possibility that some ultra-refractory ocean island harzburgites have formed at mid-ocean ridges, we favor a model in which they formed in a process spatially and temporally unrelated to the formation of the oceanic plate and the host plume. As a result of their whole-rock compositions, ultra-refractory harzburgites have a very high solidus temperature at a given pressure, low densities and very high viscosities, and will tend to accumulate at the top of the convecting mantle. They may be preserved as fragments in the convecting mantle over long periods of time and be preferentially incorporated into newly formed lithosphere. |
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Programme |
444 |
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ISSN |
0022-3530 |
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Notes |
10.1093/petrology/egn023 |
Approved |
yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5566 |
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Author |
Biessy, G.; Dauteuil, O.; Van Vliet-Lanoë, B.; Wayolle, A. |
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Title |
Fast and partitioned postglacial rebound of southwestern Iceland |
Type |
Journal Article |
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Year |
2008 |
Publication |
Tectonics |
Abbreviated Journal |
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Volume |
27 |
Issue |
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Pages |
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Keywords |
glacio-isostasy; rebound; rheology; 5475 Planetary Sciences: Solid Surface Planets: Tectonics; 5416 Planetary Sciences: Solid Surface Planets: Glaciation; 4556 Oceanography: Physical: Sea level: variations and mean; 8033 Structural Geology: Rheology: mantle |
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Abstract |
Located both on the Mid-Atlantic Ridge and above a mantle plume, Iceland is subject to horizontal and vertical motions. Many studies described these deformations in terms of rifting episodes that have combined both extensional tectonics and magmatism. However, few studies have described the glacio-isostatic response induced by the retreat of the Weichselian ice cap. The melting of this ice cap induced a postglacial rebound for the whole of Iceland that may be controlled by the geodynamic setting and the rheological layering of the lithosphere. This study is devoted to (1) understanding the Holocene rebound on the southwestern coast and (2) estimating the asthenosphere viscosity and depth beneath Iceland. Two stages of holocene evolution were determined by means of GPS profiles, morphological observations, and data compilation. The first stage corresponds to a vertical uplift of 67.5 to 157.5 m. It started at 10,000 years BP and ended at 8500 years BP implying uplift rates between 4.5 and 10.5 cm/a. It was a quick isostatic response to the fast ice retreat. The second stage had vertical motion of tens of meters with a probable tectonic origin and started at 8500 years BP. The uplift rate is 1 to 2 orders of magnitude slower than the one during the first stage. Uplift partitioning during the first stage was controlled by the thermal state of the lithosphere, the highest geothermal flux inducing the maximum uplift rates. The relaxation time for uplift provides a viscosity estimate of 5.4–5.8 × 1019 Pa s for the asthenosphere. This value is similar to those determined for glacial areas in different continental contexts. However, the flexural wavelength indicates a shallower asthenosphere than that occurring in continental domains. Therefore this study highlights a coupling between the thermal structure of the Icelandic asthenosphere and the glacial rebound. |
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Programme |
316 |
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Publisher |
American Geophysical Union |
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ISSN |
0278-7407 |
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Approved |
yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5569 |
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Author |
Caillon, N.; Jouzel, J.; Severinghaus, J.P.; Chappellaz, J.; Blunier, T. |
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Title |
A novel method to study the phase relationship between Antarctic and Greenland climate |
Type |
Journal Article |
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Year |
2003 |
Publication |
Geophysical research letters |
Abbreviated Journal |
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Volume |
30 |
Issue |
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Pages |
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Keywords |
3344 Meteorology and Atmospheric Dynamics: Paleoclimatology; 4267 Oceanography: General: Paleoceanography; 1827 Hydrology: Glaciology; 4870 Oceanography: Biological and Chemical: Stable isotopes; 1620 Global Change: Climate dynamics |
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Abstract |
A classical method for understanding the coupling between northern and southern hemispheres during millennial-scale climate events is based on the correlation between Greenland and Antarctic ice core records of atmospheric composition. Here we present a new approach based on the use of a single Antarctic ice core in which measurements of methane concentration and inert gas isotopes place constraints on the timing of a rapid climate change in the North and of its Antarctic counterpart. We applied it to the Marine Isotope Stage (MIS) 5d/c transition early in the last glaciation ?108 ky BP. Our results indicate that the Antarctic temperature increase occurred 2 ky before the methane increase, which is used as a time marker of the warming in the Northern Hemisphere. This result is in agreement with the “bipolar seesaw” mechanism used to explain the phase relationships documented between 23 and 90 ky BP [
Blunier and Brook, 2001]. |
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Programme |
902 |
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Publisher |
American Geophysical Union |
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0094-8276 |
ISBN |
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yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5649 |
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