| |
Records |
Links  |
|
Author |
Miyashita, Y.; Ieda, A.; Kamide, Y.; Machida, S.; Mukai, T.; Saito, Y.; Liou, K.; Meng, C.-I.; Parks, G.K.; McEntire, R.W.; Nishitani, N.; Lester, M.; Sofko, G.J.; Villain, J.-P. |
|
| |
Title |
Plasmoids observed in the near-Earth magnetotail at X ? ?7 RE |
Type |
Journal Article |
| |
Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
|
| |
Volume |
110 |
Issue |
|
Pages |
|
|
| |
Keywords |
plasmoid; Geotail; 2723 Magnetospheric Physics: Magnetic reconnection; 2744 Magnetospheric Physics: Magnetotail; 2790 Magnetospheric Physics: Substorms; 2704 Magnetospheric Physics: Auroral phenomena; 2736 Magnetospheric Physics: Magnetosphere/ionosphere interactions |
|
| |
Abstract |
Recent studies have statistically shown that the magnetic reconnection site at substorm expansion onset is located in the magnetotail at X ? ?20 R E on average. For a substorm event that occurred at ?0153 UT on 2 July 1996, however, Geotail observed a series of tailward but slow flows with southward magnetic fields fairly close to the Earth at (X, Y) ? (?7, 9) R E
. The flows had enhancements of the total pressure and the total magnetic field as well as bidirectional field-aligned low-energy electrons in their central part. We interpret these as signatures for tailward moving small plasmoids with scales of ?0.5–3 R E
. Considering that GOES-8 observed a dipolarization at (X, Y) ? (?4, 5) R E after the expansion onset, we estimate that the magnetic reconnection occurred between the Geotail and GOES-8 positions. UVI auroral images from Polar and ground magnetic field data show that this substorm, initiated at ?20 hours MLT and ?64° magnetic latitude, was not very intense, and the period examined was not during an intense storm. The southward interplanetary magnetic field (IMF) was not very large, while the large duskward IMF persisted for more than 12 hours before the onset as well as the somewhat large solar wind dynamic pressure. It seems likely that the global ionospheric convection was not very strong. Locally enhanced convection and auroral oval expansion due to the large IMF B y and the solar wind dynamic pressure might lead to the initiation of the magnetic reconnection much closer to the Earth than usual. |
|
| |
Programme |
312;911 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0148-0227 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5619 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
De Lauretis, M.; Francia, P.; Vellante, M.; Piancatelli, A.; Villante, U.; Di Memmo, D. |
|
| |
Title |
ULF geomagnetic pulsations in the southern polar cap: Simultaneous measurements near the cusp and the geomagnetic pole |
Type |
Journal Article |
| |
Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
|
| |
Volume |
110 |
Issue |
|
Pages |
|
|
| |
Keywords |
polar cap phenomena; cusp; MHD waves and turbulence; solar wind/magnetosphere interactions; 2776 Magnetospheric Physics: Polar cap phenomena; 2706 Magnetospheric Physics: Cusp; 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions; 2752 Magnetospheric Physics: MHD waves and instabilities; 2740 Magnetospheric Physics: Magnetospheric configuration and dynamics |
|
| |
Abstract |
During November 2003, a 1-week test campaign of ULF geomagnetic field measurements was conducted at the new Italian/French base of Concordia (Dome C, Antarctic plateau), close to the geomagnetic pole, at a corrected geomagnetic latitude of ?89°S. An analysis of these measurements is presented, together with a comparison with simultaneous measurements conducted at the Italian “Mario Zucchelli” base, at Terra Nova Bay, also located in the polar cap, but at lower latitude (?80°S). The variable solar wind and interplanetary magnetic field conditions made it possible to monitor the Pc 3–4 ULF pulsation activity under different magnetospheric conditions. For quiet conditions, the pulsation power does not show evidence for a diurnal modulation at Dome C, while at Terra Nova Bay it maximizes around local magnetic noon. This result can be interpreted in terms of the different latitude of the two stations which might be linked to different magnetospheric regions: Dome C deep in the polar cap, and Terra Nova Bay approaching the cusp around noon. Conversely, during a strong geomagnetic storm, the wave activity at the two stations becomes very similar, and major ground manifestations are driven by strong solar wind pressure pulses. The clear dependence of the pulsation frequency with the interplanetary magnetic field strength suggests that upstream waves can be the source of pulsations not only at Terra Nova Bay but also at Dome C, in the deep polar cap. We also find a clear relationship between the pulsation power and the solar wind speed which is more pronounced at Dome C, where cusp-related phenomena are not present. |
|
| |
Programme |
1130 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0148-0227 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5494 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Fain, X.; Ferrari, C.P.; Gauchard, P.-A.; Magand, O.; Boutron, C. |
|
| |
Title |
Fast depletion of gaseous elemental mercury in the Kongsvegen Glacier snowpack in Svalbard |
Type |
Journal Article |
| |
Year |
2006 |
Publication |
Geophysical research letters |
Abbreviated Journal |
|
|
| |
Volume |
33 |
Issue |
|
Pages |
|
|
| |
Keywords |
0317 Atmospheric Composition and Structure: Chemical kinetic and photochemical properties; 0322 Atmospheric Composition and Structure: Constituent sources and sinks; 0330 Atmospheric Composition and Structure: Geochemical cycles; 0365 Atmospheric Composition and Structure: Troposphere: composition and chemistry; 0736 Cryosphere: Snow |
|
| |
Abstract |
Gaseous elemental mercury (GEM, Hg°) was measured in the snowpack interstitial air on the Kongsvegen Glacier (Svalbard) between the surface and 190 cm depth. A rapid depletion of GEM from ?5 to 0.4 ng.m?3 in the snowpack air was measured in less than 8 hours at a calculated depletion rate of ?0.5–0.7 ng.m?3.h?1 while concentration of GEM above the snow stayed constant about 1.7 ng.m?3. This depletion could only be explained by chemical processes and this study suggests that Br. could be the most important reactant for the oxidation of GEM in the interstitial snow air. The lifetime of GEM was estimated to be ?10 minutes with second order reaction rate constant between GEM and Br. of about ?2 × 10?11 cm?3.molecule?1.s?1. These first experimental kinetic values for GEM oxidation in the snow air are in good agreement with both theoretical and modelling studies previously reported. |
|
| |
Programme |
399 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0094-8276 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5592 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Lambotte, S.; Rivera, L.; Hinderer, J. |
|
| |
Title |
Rupture length and duration of the 2004 Aceh-Sumatra earthquake from the phases of the Earth's gravest free oscillations |
Type |
Journal Article |
| |
Year |
2006 |
Publication |
Geophysical research letters |
Abbreviated Journal |
|
|
| |
Volume |
33 |
Issue |
|
Pages |
|
|
| |
Keywords |
3255 Mathematical Geophysics: Spectral analysis; 7209 Seismology: Earthquake dynamics; 7215 Seismology: Earthquake source observations; 7255 Seismology: Surface waves and free oscillations; 7260 Seismology: Theory |
|
| |
Abstract |
The Aceh-Sumatra 2004 earthquake strongly excited the Earth's free oscillations. Well separated split multiplets provide useful information on the earthquake source. Particularly, the phases of split singlets constrain the duration, rupture length and mean rupture velocity. We analyze the initial phases of some of the Earth's gravest free oscillations (0
S
2, 0
S
3, 0
S
0 and 1
S
0) in order to constrain the space-time finiteness of the source. We use recordings of vertical broadband seismometers and superconducting gravimeters from several worldwide geophysical networks. We estimate a rupture length of about 1220 km, a source time duration of about 500 s, and a mean rupture velocity of 2.4 km/s. |
|
| |
Programme |
133;906 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0094-8276 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5627 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Andersen, O.B.; Seneviratne, S.I.; Hinderer, J.; Viterbo, P. |
|
| |
Title |
GRACE-derived terrestrial water storage depletion associated with the 2003 European heat wave |
Type |
Journal Article |
| |
Year |
2005 |
Publication |
Geophysical research letters |
Abbreviated Journal |
|
|
| |
Volume |
32 |
Issue |
|
Pages |
|
|
| |
Keywords |
1640 Global Change: Remote sensing; 1655 Global Change: Water cycles; 1836 Hydrology: Hydrological cycles and budgets; 1812 Hydrology: Drought |
|
| |
Abstract |
The GRACE twin satellites reveal large inter-annual terrestrial water-storage variations between 2002 and 2003 for central Europe. GRACE observes a negative trend in regional water storage from 2002 to 2003 peaking at ?7.8 cm in central Europe with an accuracy of 1 cm. The 2003 excess terrestrial water storage depletion observed from GRACE can be related to the record-breaking heat wave that occurred in central Europe in 2003. We validate the measurements from GRACE using two independent hydrological estimates and direct gravity observations from superconducting gravimeters in Europe. All datasets agree well with the GRACE measurements despite the disparity of the employed information; the difference between datasets tends to be within GRACE margin of error. The April-to-August terrestrial water storage depletion is found to be significantly larger in 2003 than in 2002 from both models and observations. |
|
| |
Programme |
337 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0094-8276 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5597 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Domine, F.; Taillandier, A.S.; Simpson, W.R.; Severin, K. |
|
| |
Title |
Specific surface area, density and microstructure of frost flowers |
Type |
Journal Article |
| |
Year |
2005 |
Publication |
Geophysical research letters |
Abbreviated Journal |
|
|
| |
Volume |
32 |
Issue |
|
Pages |
|
|
| |
Keywords |
0736 Cryosphere: Snow; 0750 Cryosphere: Sea ice; 0754 Cryosphere: Leads |
|
| |
Abstract |
Frost flowers often grow on new sea ice. They are thought to have a high specific surface area (SSA) that provides sites for heterogeneous reactions. We have measured the SSA of frost flowers using CH4 adsorption at 77 K and obtained a value of 185 (+80 ?50) cm2/g, much lower than inferred by others. Their density is 0.02 g/cm3. We calculate that the total surface area of frost flowers is 1.4 m2 per m2 of ice surface, so that they do not increase the ice surface area significantly. Their role as sites for enhanced heterogeneous reactions should be reconsidered. Frost flowers also commonly grow on fresh water and the saline brine seen on young sea ice is not necessary for their growth. Photo- and electro-micrographs reveal hollow and concave structures, typical of very fast growing crystals. The brine that wicks up frost flowers considerably perturbs their growth. |
|
| |
Programme |
437 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0094-8276 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5633 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Legagneux, L.; Domine, F. |
|
| |
Title |
A mean field model of the decrease of the specific surface area of dry snow during isothermal metamorphism |
Type |
Journal Article |
| |
Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
|
| |
Volume |
110 |
Issue |
|
Pages |
|
|
| |
Keywords |
model; isothermal snow metamorphism; Ostwald ripening; 0736 Cryosphere: Snow; 3947 Mineral Physics: Surfaces and interfaces; 1847 Hydrology: Modeling; 5112 Physical Properties of Rocks: Microstructure |
|
| |
Abstract |
The surface area of snow that is accessible to gases is an essential parameter for quantifying the exchange of trace gases between the snowpack and the atmosphere and is called the specific surface area (SSA). Snow SSA decreases during metamorphism, but this is not described in current snow models owing to the complexity of the physics and geometry of snow. In this paper, we test whether it is possible to model snow SSA changes during isothermal metamorphism without accounting for all the complexity of the three-dimensional (3-D) structure of real snow. We have developed a mean field model of snow metamorphism under isothermal conditions, grounded in the theoretical framework of transient Ostwald ripening and representing snow as a distribution of spherical particles. Analytical expressions of the growth rates of these spheres are obtained, and the evolution of two measurable parameters that characterize snow geometry, the SSA and the distribution of radii of curvature (DRC), are simulated and compared to experimental data obtained by X-ray tomography. The qualitative effects of temperature, snow density, and the condensation coefficient on the rate of SSA decrease are examined. The model predicts very well the rate of evolution of the particle size distribution, which validates our physical description of isothermal metamorphism. In particular, we find that vapor phase diffusion is rate limiting. However, the calculation of the SSA from the DRC appears delicate and evidences too crude approximations in our description of the 3-D geometry of snow. Finally, it is stressed that the initial DRC can greatly influence the rate of SSA decrease, while experimental measurements of the rate of SSA decrease suggest that all snow types evolve in a similar way. It is thus proposed that most natural fresh snows have similar DRCs. |
|
| |
Programme |
437 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0148-0227 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5650 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Verhoeven, O.; Rivoldini, A.; Vacher, P.; Mocquet, A.; Choblet, G.; Menvielle, M.; Dehant, V.; Van Hoolst, T.; Sleewaegen, J.; Barriot, J.-P.; Lognonné, P. |
|
| |
Title |
Interior structure of terrestrial planets: Modeling Mars' mantle and its electromagnetic, geodetic, and seismic properties |
Type |
Journal Article |
| |
Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
|
| |
Volume |
110 |
Issue |
|
Pages |
|
|
| |
Keywords |
internal structure; Mars; network science; 5430 Planetary Sciences: Solid Surface Planets: Interiors; 6225 Planetary Sciences: Solar System Objects: Mars; 3672 Mineralogy and Petrology: Planetary mineralogy and petrology |
|
| |
Abstract |
We present a new procedure to describe the one-dimensional thermodynamical state and mineralogy of any Earth-like planetary mantle, with Mars as an example. The model parameters are directly related to expected results from a geophysical network mission, in this case electromagnetic, geodetic, and seismological processed observations supplemented with laboratory measurements. We describe the internal structure of the planet in terms of a one-dimensional model depending on a set of eight parameters: for the crust, the thickness and the mean density, for the mantle, the bulk volume fraction of iron, the olivine volume fraction, the pressure gradient, and the temperature profile, and for the core, its mass and radius. Currently, available geophysical and geochemical knowledge constrains the range of the parameter values. In the present paper, we develop the forward problem and present the governing equations from which synthetic data are computed using a set of parameter values. Among all Martian models fitting the currently available knowledge, we select eight candidate models for which we compute synthetic network science data sets. The synergy between the three geophysical experiments of electromagnetic sounding, geodesy, and seismology is emphasized. The stochastic inversion of the synthetic data sets will be presented in a companion paper. |
|
| |
Programme |
905;907 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
Bachelor's thesis |
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0148-0227 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5567 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Alexander, B.; Park, R.J.; Jacob, D.J.; Li, Q.B.; Yantosca, R.M.; Savarino, J.; Lee, C.C.W.; Thiemens, M.H. |
|
| |
Title |
Sulfate formation in sea-salt aerosols: Constraints from oxygen isotopes |
Type |
Journal Article |
| |
Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
|
| |
Volume |
110 |
Issue |
|
Pages |
|
|
| |
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 |
|
| |
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. |
|
| |
Programme |
399 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0148-0227 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5554 |
|
| Permanent link to this record |
| |
|
| |
|
Author |
Masson-Delmotte, V.; Landais, A.; Stievenard, M.; Cattani, O.; Falourd, S.; Jouzel, J.; Johnsen, S.J.; Dahl-Jensen, D.; Sveinsbjornsdottir, A.; White, J.W.C.; Popp, T.; Fischer, H. |
|
| |
Title |
Holocene climatic changes in Greenland: Different deuterium excess signals at Greenland Ice Core Project (GRIP) and NorthGRIP |
Type |
Journal Article |
| |
Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
|
| |
Volume |
110 |
Issue |
|
Pages |
|
|
| |
Keywords |
paleoclimate; polar ice sheet; water cycle; 1041 Geochemistry: Stable isotope geochemistry; 0724 Cryosphere: Ice cores; 1620 Global Change: Climate dynamics; 1655 Global Change: Water cycles; 3344 Atmospheric Processes: Paleoclimatology |
|
| |
Abstract |
Water stable isotope measurements (?D and ?18O) have been conducted on the Holocene part of two deep Greenland ice cores (Greenland Ice Core Project (GRIP) and NorthGRIP), located ?320 km apart. These combined measurements provide the first two continuous Greenland Holocene deuterium excess profiles (d = ?D ? 8?18O), a parameter strongly influenced by changes in moisture sources. We discuss here temporal and regional fluctuations of the deuterium excess within central to north Greenland, with a mean temporal resolution of ?4 years. Although GRIP and NorthGRIP exhibit similar annual mean surface temperatures and ?18O levels, a significant offset of modern deuterium excess is observed between the two sites. We attribute this offset to a different mix of modern moisture sources, pointing to regional-scale differences in moisture advection toward Greenland. The common long-term deuterium excess Holocene increasing trend is probably related to the increased relative contribution of low-latitude moisture to Greenland snowfall, in response to the change in the Earth obliquity, as symmetrically observed in Antarctica. Three abrupt declines punctuate the GRIP excess record (8.2, 4.5, and 0.35 ka BP), suggesting associated reorganizations of the northern high latitudes hydrological cycle. The 8.2 ka BP event is characterized by (1) a rapid cooling followed by a progressive warming and (2) a deuterium excess cooling restricted to GRIP, therefore totally different from rapid events during glacial times. By contrast, the NorthGRIP deuterium excess record is more stable. We propose that a slightly larger proportion of moisture supplied by local storm tracks to GRIP induces an isotopic compensation mechanism between simultaneous site and source temperature coolings, resulting in a rather temperature-insensitive ?18O profile, together with well-marked deuterium excess amplitudes. NorthGRIP ?18O seems less biased by isotopic processes and should provide a more reliable past temperature record. |
|
| |
Programme |
458 |
|
| |
Campaign |
|
|
| |
Address |
|
|
| |
Corporate Author |
|
Thesis |
|
|
| |
Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
|
| |
Language |
|
Summary Language |
|
Original Title |
|
|
| |
Series Editor |
|
Series Title |
|
Abbreviated Series Title |
|
|
| |
Series Volume |
|
Series Issue |
|
Edition |
|
|
| |
ISSN |
0148-0227 |
ISBN |
|
Medium |
|
|
| |
Area |
|
Expedition |
|
Conference |
|
|
| |
Notes |
|
Approved |
yes |
|
| |
Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5508 |
|
| Permanent link to this record |
