| Records |
| Author |
Schwander, J.; Jouzel, J.; Hammer, C.U.; Petit, J.-R.; Udisti, R.; Wolff, E. |
| Title |
A Tentative Chronology for the EPICA Dome Concordia Ice Core |
Type |
Journal Article |
| Year |
2001 |
Publication |
Geophysical research letters |
Abbreviated Journal |
|
| Volume |
28 |
Issue |
|
Pages |
|
| Keywords |
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| Abstract |
A tentative age scale (EDC1) for the last 45 kyr is established for the new 788-m EPICA Dome C ice core using a simple ice flow model. The age of volcanic eruptions, the end of the Younger Dryas event, and the estimated depth and age of elevated 10Be, about 41 kyr ago were used to calibrate the model parameters. The uncertainty of EDC1 is estimated to ± 10 yr for 0 to 700 yr BP, up to ± 200 yr back to 10 kyr BP, and up to ± 2 kyr back to 41 kyr BP. The age of the air in the bubbles is calculated with a firn densification model. In the Holocene the air is about 2000 yr younger than the ice and about 5500 yr during the last glacial maximum. |
| Programme |
960 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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Publisher  |
American Geophysical Union |
Place of Publication |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0094-8276 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5558 |
| Permanent link to this record |
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| |
| Author |
Rivier, L.; Ciais, P.; Hauglustaine, D.A.; Bakwin, P.; Bousquet, P.; Peylin, P.; Klonecki, A. |
| Title |
Evaluation of SF6, C2Cl4, and CO to approximate fossil fuel CO2 in the Northern Hemisphere using a chemistry transport model |
Type |
Journal Article |
| Year |
2006 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
| Volume |
111 |
Issue |
|
Pages |
|
| Keywords |
fossil fuel proxy; SF 6; C 2 Cl 4; CO; carbon fluxes; emissions; 0322 Atmospheric Composition and Structure: Constituent sources and sinks; 0368 Atmospheric Composition and Structure: Troposphere: constituent transport and chemistry; 0365 Atmospheric Composition and Structure: Troposphere: composition and chemistry; 0345 Atmospheric Composition and Structure: Pollution: urban and regional |
| Abstract |
The distribution of the fossil fuel component in atmospheric CO2 cannot be measured directly at a cheap cost. Could anthropogenic tracers with source patterns similar to fossil fuel CO2 then be used for that purpose? Here we present and evaluate a methodology using surrogate tracers, CO, SF6, and C2Cl4, to deduce fossil fuel CO2. A three-dimensional atmospheric chemistry transport model is used to simulate the relationship between each tracer and fossil fuel CO2. In summertime the regression slopes between fossil fuel CO2 and surrogate tracers show large spatial variations for chemically active tracers (CO and C2Cl4), although C2Cl4 presents less scatter than CO. At two tall tower sites in the United States (WLEF, Wisconsin, and WITN, North Carolina), we found that in summertime the C2Cl4 (CO) versus fossil CO2 slope is on average up to 15% (25%) higher than in winter. We show that for C2Cl4 this seasonal variation is due to OH oxidation. For CO the seasonal variation is due to both chemistry and mixing with nonanthropogenic CO sources. In wintertime the three surrogate tracers SF6, C2Cl4, and CO are about equally as good indicators of the presence of fossil CO2. However, our model strongly underestimates the variability of SF6 at both towers, probably because of unaccounted for emissions. Hence poor knowledge of emission distribution hampers the use of SF6 as a surrogate tracer. From a practical point of view we recommend the use of C2Cl4 as a proxy of fossil CO2. We also recommend the use of tracers to separate fossil CO2. Despite the fact that the uncertainty on the regression slope is on the order of 30%, the tracer approach is likely to have less bias than when letting one model with one inventory emission map calculate the fossil CO2 distribution. |
| Programme |
439 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
American Geophysical Union |
Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0148-0227 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5588 |
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| |
| Author |
Thuillier, G.; Perrin, J.-M.; Lathuillère, C.; Hersé, M.; Fuller-Rowell, T.; Codrescu, M.; Huppert, F.; Fehrenbach, M. |
| Title |
Dynamics in the polar thermosphere after the coronal mass ejection of 28 October 2003 observed with the EPIS interferometer at Svalbard |
Type |
Journal Article |
| Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
| Volume |
110 |
Issue |
|
Pages |
|
| Keywords |
thermosphere; CME; neutral winds; EPIS; ESR; 0310 Atmospheric Composition and Structure: Airglow and aurora; 0358 Atmospheric Composition and Structure: Thermosphere: energy deposition; 7513 Solar Physics, Astrophysics, and Astronomy: Coronal mass ejections |
| Abstract |
The upper atmosphere dynamics in the polar cap is mainly driven by ion-drag momentum sources imposed by the mapping of magnetosphere convection into the thermosphere/ionosphere and by Joule and auroral particle heating. Auroral particles also enhance conductivity particularly in the middle and lower ionosphere. Changes in the magnetospheric energy and momentum sources can significantly modify the wind circulation during geomagnetic storms. To observe these effects, a Michelson interferometer has been installed in Svalbard to measure winds in the thermosphere. Prior to 30 October 2003, cloud cover over Svalbard rendered the conditions unfavorable for optical observation. However, meteorological conditions improved after this date to enable the thermospheric response to the 28 October coronal mass ejection to be made. During quiet geomagnetic conditions measured wind velocities were in good agreement with those predicted by the Horizontal Wind Model (HWM). During disturbed geomagnetic conditions, HWM tended to underestimate the observed velocities. Comparison of the wind observations with a physical model tended to show reasonable agreement during both the strongly driven and recovery phase of the storm. Although the physical model did not always capture the timing of the rapid changes in the wind response in the early phase of the storm, the amplitudes of the fluctuations were in good agreement. After the initial phase the physical model agreed well with both the timing and amplitude of the meridional and zonal wind fluctuations. The meridional wind component was also derived from the EISCAT Svalbard Radar ion velocity and was found to be in close agreement with the optical winds observations. |
| Programme |
384 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
American Geophysical Union |
Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0148-0227 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
|
Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5585 |
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| |
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| |
| Author |
Landais, A.; Steffensen, J.P.; Caillon, N.; Jouzel, J.; Masson-Delmotte, V.; Schwander, J. |
| Title |
Evidence for stratigraphic distortion in the Greenland Ice Core Project (GRIP) ice core during Event 5e1 (120 kyr BP) from gas isotopes |
Type |
Journal Article |
| Year |
2004 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
| Volume |
109 |
Issue |
|
Pages |
|
| Keywords |
1827 Hydrology: Glaciology; 3344 Meteorology and Atmospheric Dynamics: Paleoclimatology; 3349 Meteorology and Atmospheric Dynamics: Polar meteorology |
| Abstract |
The disturbed stratigraphy of the ice in the lowest 10% of the Greenland GRIP ice core has been previously demonstrated using gas measurements (?18O of O2 and CH4) on a few meters depth scale. However, rapid ice isotopic variations (on the scale of 20 cm) are experienced in the bottom of the GRIP ice core with complex chemical signatures that make them difficult to reconcile with a disturbed stratigraphy of the ice. This is the case for event 5e1, first described as a dramatic cooling 120 kyr BP. We analyzed at a 5 cm resolution the isotopic composition of the air from 2 m of the GRIP bottom ice core covering event 5e1. The ?15N measurements, combined with a basic firn modeling, lead to the solid conclusion that the rapid event 5e1 is not a climatic event. Rapid variations of ?18O of O2 (?18Oatm) are in agreement with a disturbed ice stratigraphy. However, the double peak shape of the ?18Oatm, recalling chemical data at the same depth, requires processes of diffusion after the mixing or even postcoring, placing limits to the interpretation of some classical paleoclimatic proxies in small scale mixed ice (<1 m). |
| Programme |
458 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
American Geophysical Union |
Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0148-0227 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5647 |
| Permanent link to this record |
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| |
| Author |
Park, Y.-H.; Roquet, F.; Vivier, F. |
| Title |
Quasi-stationary ENSO wave signals versus the Antarctic Circumpolar Wave scenario |
Type |
Journal Article |
| Year |
2004 |
Publication |
Geophysical research letters |
Abbreviated Journal |
|
| Volume |
31 |
Issue |
|
Pages |
|
| Keywords |
4215 Oceanography: General: Climate and interannual variability; 4207 Oceanography: General: Arctic and Antarctic oceanography; 4522 Oceanography: Physical: El Nino |
| Abstract |
Two conflicting views on the causal mechanism of the Antarctic interannual variability often appear in the literature, i.e., whether it is remotely teleconnected to tropical ENSO events or is a self-sustained eastward propagating circumpolar wave generated locally by an ocean-atmosphere coupling mechanism. Using a Fourier decomposition into stationary and propagating components of several oceanic and atmospheric variables, we show that most of the Antarctic interannual variability can be explained by a geographically phase-locked standing wave train linked to tropical ENSO episodes. This ENSO-modulated quasi-stationary variability is not zonally uniform, rather, the strongest ENSO impact is consistently concentrated in the Pacific sector of the Southern Ocean. The eastward propagating wave component is found to be not only minor (25% of variability) but also intermittent in phase, yielding little support for the so-called Antarctic Circumpolar Wave scenario. |
| Programme |
335 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
American Geophysical Union |
Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0094-8276 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
|
Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5624 |
| Permanent link to this record |
| |
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| |
| Author |
Senior, C.; Cerisier, J.-C.; Thorolfsson, A.; Lester, M. |
| Title |
Propagation in the ionosphere of convection changes following a sharp interplanetary magnetic field By transition |
Type |
Journal Article |
| Year |
2002 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
| Volume |
107 |
Issue |
|
Pages |
|
| Keywords |
2463 Ionosphere: Plasma convection; 2740 Magnetospheric Physics: Magnetospheric configuration and dynamics |
| Abstract |
The nature of the response of the ionospheric convection to changes in the interplanetary magnetic field (IMF), either quasi-simultaneous over the polar cap and auroral region or propagating with the flow velocity from the noon sector, remains to be understood. We examine the changes in the ionospheric plasma convection associated with a negative to positive transition in the dawn-dusk component (By) of the IMF. A special mode of operation of the SuperDARN HF radars has been used, which provided both a large field of view and high-resolution convection data on three beams. Close to noon, the most characteristic response concerns the position in magnetic local time (MLT) of the merging gap, the ionospheric footprint of the magnetopause reconnection line, which moves longitudinally with a velocity of 1 km/s. In addition, modifications of the convection, which are indirectly related to this motion, are observed. We attribute them to the “quasi-instantaneous” effect related to the incompressibility of the plasma. Far from noon, in the morning sector, the convection reacts with an intermediate delay, which is neither instantaneous nor compatible with the above propagation velocity. A timing of the transition, based on the IMP 8 and Geotail satellites, located on the dawn flank of the magnetosphere and at the nose of the magnetopause, respectively, indicates that the ionospheric perturbation originates at the impact site of the By transition close to 1300 MLT, with a maximum delay of 3 min after it hits the nose of the magnetopause. |
| Programme |
312;911 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
Bachelor's thesis |
| Publisher |
American Geophysical Union |
Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0148-0227 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
|
Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5623 |
| Permanent link to this record |
| |
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| |
| Author |
Park, Y.-H. |
| Title |
Determination of the surface geostrophic velocity field from satellite altimetry |
Type |
Journal Article |
| Year |
2004 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
| Volume |
109 |
Issue |
|
Pages |
|
| Keywords |
4512 Oceanography: Physical: Currents; 4528 Oceanography: Physical: Fronts and jets; 4556 Oceanography: Physical: Sea level variations |
| Abstract |
Presently available marine geoid models are not accurate enough to extract the mean surface circulation directly from satellite altimetry. A novel method for estimating the mean velocity field of major ocean current systems is derived from the free surface boundary condition. With a given quasi-geostrophic balance for the horizontal surface flow, a scaling analysis of this boundary condition indicates that although the vertical velocity w is mostly balanced by the local change of the free surface, ???/?t, useful information on the mean current ($\overline{u}$, $\overline{v}$) is contained in a small ageostrophic departure (???/?t ? w). Our method consists in the development of a simple algebraic equation with two unknowns ($\overline{u}$, $\overline{v}$) and an adjustable parameter $\widetilde{\alpha}$ associated with ???/?t, assuming that the latter is proportional to (???/?t ? w). Most interestingly, ???/?t and all other coefficients of the equation can be determined from altimetry. The altimeter data used is combined TOPEX/Poseidon-ERS gridded data, and the solution is obtained by least squares, minimizing the contribution from the time-variable part of the parameter $\widetilde{\alpha}$ and prescribing the zonal direction of the mean current. The method, which is found to be particularly useful for quasi-zonal high-energy current systems, has been validated against direct observations in the Gulf Stream and Southern Ocean. Comparisons with direct observations and Monte Carlo experiments suggest an overall solution error of about 10 cm s?1. Once calibrated against regional velocity statistics, this method will be able to determine from altimetry the mean or instantaneous surface velocity field down to the frontal scale, with a realism that has been inaccessible because of the geoid constraint. |
| Programme |
335 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
American Geophysical Union |
Place of Publication |
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Editor |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0148-0227 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5582 |
| Permanent link to this record |
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| Author |
Duval, P.; Montagnat, M. |
| Title |
Comment on “Superplastic deformation of ice: Experimental observations” by D. L. Goldsby and D. L. Kohlstedt |
Type |
Journal Article |
| Year |
2002 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
| Volume |
107 |
Issue |
|
Pages |
|
| Keywords |
1827 Hydrology: Glaciology; 1863 Hydrology: Snow and ice; 3902 Mineral Physics: Creep and deformation; 5120 Physical Properties of Rocks: Plasticity, diffusion, and creep |
| Abstract |
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| Programme |
902 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
American Geophysical Union |
Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0148-0227 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5637 |
| Permanent link to this record |
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| Author |
Legrand, M.; Preunkert, S.; Wagenbach, D.; Fischer, H. |
| Title |
Seasonally resolved Alpine and Greenland ice core records of anthropogenic HCl emissions over the 20th century |
Type |
Journal Article |
| Year |
2002 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
| Volume |
107 |
Issue |
|
Pages |
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| Keywords |
0325 Atmospheric Composition and Structure: Evolution of the atmosphere; 0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry; 0322 Atmospheric Composition and Structure: Constituent sources and sinks |
| Abstract |
The continuous highly resolved records of Cl?, Na+, and Ca2+ in ice cores from Col du Dôme (4250 m elevation, French Alps) and Summit (3240 m elevation, central Greenland) are used to reconstruct the history of atmospheric HCl pollution over Europe and Greenland since the early 20th century. The evaluation of the HCl amount in summer snow deposits at high-elevation Alpine sites is complex since continental emissions (soils, halide evaporites, and possibly manure-fertilized fields) account for 80% of the chloride budget and only one fifth of Cl? is related to HCl. During the preindustrial era the HCl content of summer Alpine snow layers fluctuated between 0 and 6 ng g?1, likely in relation with a highly variable interannual biomass burning activity in western Europe. From 1925 to 1960 the HCl levels were slightly higher (3–9 ng g?1), mainly due to growing coal burning emissions in western Europe. In the late 1960s a sharp increase of HCl levels (up to 17 ng g?1) took place as a result of the setup of waste incineration in western Europe, this process contributing 3–4 times more than coal combustion to the HCl budget of summer Alpine snow layers deposited between 1970 and 1990. In winter, sea spray emissions dominate (?78%) the total Cl? level of Alpine snow layers. The HCl trend in these snow layers remained limited to ?2 ng g?1 over the 20th century, likely in relation to waste incineration after 1965. In Greenland snow layers most of particulate Cl? originates from sea spray, 1/3 to 2/3 of Cl? being present as HCl in spring and summer, respectively. The Greenland HCl ice core records indicate a preindustrial HCl level close to 4 ng g?1, which is found to be mainly due to the sea-salt dechlorination, while the contribution of passive volcanic HCl emissions at high northern latitudes can be neglected. The input from sea-salt dechlorination has been enhanced by a factor of 2–3 during the second half of the 20th century similarly to the increase of the atmospheric acidity in response to growing NOx and SO2 anthropogenic emissions. |
| Programme |
414 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
American Geophysical Union |
Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0148-0227 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5629 |
| Permanent link to this record |
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| Author |
Savarino, J.; Bekki, S.; Cole-Dai, J.; Thiemens, M.H. |
| Title |
Evidence from sulfate mass independent oxygen isotopic compositions of dramatic changes in atmospheric oxidation following massive volcanic eruptions |
Type |
Journal Article |
| Year |
2003 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
| Volume |
108 |
Issue |
|
Pages |
|
| Keywords |
0340 Atmospheric Composition and Structure: Middle atmosphere—composition and chemistry; 0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry; 0370 Atmospheric Composition and Structure: Volcanic effects; 1040 Geochemistry: Isotopic composition/chemistry; 1863 Hydrology: Snow and ice |
| Abstract |
Oxygen isotopic ratio measurements (?17O and ?18O) of background and volcanic sulfate preserved in South Pole snow and ice were used to investigate the impact on the oxidation state of the atmosphere by explosive volcanic eruptions. By comparing different paleovolcanic events, we observe a difference in the SO2 oxidation pathway between moderate (tens of teragrams (Tg) of SO2) and massive (hundreds of Tg) eruptions. Both isotopic data and numerical simulations suggest the shutdown of stratospheric OH chemistry and the opening of unaccounted oxidation channels for SO2, such as the reaction with O(3P) atoms when hundreds of Tg of SO2 are injected into the stratosphere. It is very likely that oxidation rates and pathways and concentrations of most traces gases are also dramatically affected, with potentially important implications for climate forcing. |
| Programme |
457 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
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| Publisher |
American Geophysical Union |
Place of Publication |
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Editor |
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| Language |
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Summary Language |
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Original Title |
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| Series Editor |
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Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
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Edition |
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| ISSN |
0148-0227 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
|
Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5589 |
| Permanent link to this record |
