| Records |
| 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 |
|
| 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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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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Edition |
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| ISSN |
0148-0227 |
ISBN |
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Conference |
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| Notes |
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Approved |
yes |
Call Number  |
IPEV @ Thierry.Lemaire @ |
Serial |
5589 |
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| Author |
Frezzotti, M.; Gandolfi, S.; Urbini, S. |
| Title |
Snow megadunes in Antarctica: Sedimentary structure and genesis |
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; 1894 Hydrology: Instruments and techniques; 3322 Meteorology and Atmospheric Dynamics: Land/atmosphere interactions; 5470 Planetology: Solid Surface Planets: Surface materials and properties |
| Abstract |
Megadune fields occupy large areas in the interior of the East Antarctic ice sheet and are the result of unusual snow accumulation and redistribution processes. They therefore are important to surface mass balance and ice core interpretation. Field observations (GPS, GPR, and surface measurements) have provided a detailed description of megadune sedimentation and morphology over a 70 km2 area, located 200 km east of Dome C. A combination of remote sensing analysis (using Landsat and satellite radar altimetry) and field measurements indicate that slope in the prevailing wind direction (SPWD) and climatic conditions play a crucial role in megadune genesis. The megadune areas tend to be characterized by slightly steeper regional slope and the presence of highly persistent katabatic winds. The megadunes represent 2 to 4 m amplitude waves of 2 to 5 km wavelength formed by variable net accumulation, ranging between 25% (leeward faces) to 120% (windward faces) of the accumulation in adjacent nonmegadune areas. Leeward faces are characterized by glazed, sastrugi-free surfaces and extensive depth hoar formation. Windward faces are covered by large rough sastrugi up to 1.5 m in height. |
| Programme |
961 |
| 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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| 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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| 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 |
5631 |
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| Author |
Goujon, C.; Barnola, J.-M.; Ritz, C. |
| Title |
Modeling the densification of polar firn including heat diffusion: Application to close-off characteristics and gas isotopic fractionation for Antarctica and Greenland sites |
Type |
Journal Article |
| Year |
2003 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
| Volume |
108 |
Issue |
|
Pages |
|
| Keywords |
1827 Hydrology: Glaciology; 1863 Hydrology: Snow and ice; 3344 Meteorology and Atmospheric Dynamics: Paleoclimatology |
| Abstract |
Modeling the densification of polar firn is essential to estimate variations of close-off characteristics (density, close-off depth, delta age) in relation with past climate parameters (temperature and accumulation rates). Furthermore, the air composition in the firn is modified by gravitational and thermal fractionation, and stable isotope measurements of permanent gases like nitrogen or argon can provide information on the amplitude of these fractionations. In this work, we propose a new model coupling firn densification and heat diffusion. In addition to the determination of the firn thickness and gas-ice age differences, the model allows a reconstruction of the time evolution of the temperature for different sites in Antarctica (Vostok) and Greenland (GISP2) and therefore the evolution of gravitational and thermal isotopic fractionations in firn. Under present-day conditions, the modeled profiles are in good agreement with the available temperature measurements in firn. For sites with low accumulation rates such as Vostok, the results show the existence of temperature gradients in the firn column even when no rapid climatic changes occur. The comparison of the modeled ?15N results to measurements allows to better constrain the ?18O-temperature relationship, used to infer the surface temperature history, and for GISP2, the model validates the long-term borehole-based temperature. |
| 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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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 |
5616 |
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| Author |
Bouruet-Aubertot, P.; Mercier, H.; Gaillard, F.; Lherminier, P. |
| Title |
Evidence of strong inertia-gravity wave activity during the POMME experiment |
Type |
Journal Article |
| Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
| Volume |
110 |
Issue |
|
Pages |
|
| Keywords |
inertia-gravity waves, turbulent mixing; 4544 Oceanography: Physical: Internal and inertial waves; 4568 Oceanography: Physical: Turbulence, diffusion, and mixing processes; 4572 Oceanography: Physical: Upper ocean and mixed layer processes |
| Abstract |
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| Programme |
417 |
| 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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Series Title |
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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 |
5590 |
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| Author |
Savarino, J.; Romero, A.; Cole-Dai, J.; Bekki, S.; Thiemens, M.H. |
| Title |
UV induced mass-independent sulfur isotope fractionation in stratospheric volcanic sulfate |
Type |
Journal Article |
| 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 |
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| Abstract |
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| 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 |
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 |
5537 |
| Permanent link to this record |
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| 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 |
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| 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 |
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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 |
5650 |
| Permanent link to this record |
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| Author |
Monnin, E.; Indermuhle, A.; Dallenbach, A.; Fluckiger, J.; Stauffer, B.; Stocker, T.F.; Raynaud, D.; Barnola, J.-M. |
| Title |
Atmospheric CO2 Concentrations over the Last Glacial Termination |
Type |
Journal Article |
| Year |
2001 |
Publication |
Science |
Abbreviated Journal |
Science |
| Volume |
291 |
Issue |
5501 |
Pages |
112-114 |
| Keywords |
|
| Abstract |
A record of atmospheric carbon dioxide (CO2) concentration during the transition from the Last Glacial Maximum to the Holocene, obtained from the Dome Concordia, Antarctica, ice core, reveals that an increase of 76 parts per million by volume occurred over a period of 6000 years in four clearly distinguishable intervals. The close correlation between CO2 concentration and Antarctic temperature indicates that the Southern Ocean played an important role in causing the CO2 increase. However, the similarity of changes in CO2 concentration and variations of atmospheric methane concentration suggests that processes in the tropics and in the Northern Hemisphere, where the main sources for methane are located, also had substantial effects on atmospheric CO2 concentrations |
| Programme |
960 |
| Campaign |
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Place of Publication |
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Series Issue |
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Edition |
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| ISSN |
0036-8075 |
ISBN |
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| Area |
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Expedition |
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Conference |
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| Notes |
10.1126/science.291.5501.112 |
Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5574 |
| Permanent link to this record |
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| Author |
Simpson, W.R.; Alvarez-Aviles, L.; Douglas, T.A.; Sturm, M.; Domine, F. |
| Title |
Halogens in the coastal snow pack near Barrow, Alaska: Evidence for active bromine air-snow chemistry during springtime |
Type |
Journal Article |
| Year |
2005 |
Publication |
Geophysical research letters |
Abbreviated Journal |
|
| Volume |
32 |
Issue |
|
Pages |
|
| Keywords |
0312 Atmospheric Composition and Structure: Air/sea constituent fluxes; 0330 Atmospheric Composition and Structure: Geochemical cycles; 0365 Atmospheric Composition and Structure: Troposphere: composition and chemistry; 0368 Atmospheric Composition and Structure: Troposphere: constituent transport and chemistry; 1863 Hydrology: Snow and ice |
| Abstract |
We measured halide concentrations of snow and frost flowers in the vicinity of Barrow, Alaska. We find that the ratio of bromide to sodium in frost flowers is slightly enhanced (?10%) as compared to sea water. In contrast, the ratio of bromide to sodium in some snow samples is more than an order of magnitude enhanced, and in other samples is more than an order of magnitude depleted. We interpret the bromide depleted snow as having been processed by heterogeneous chemistry and providing reactive halogen compounds to the atmosphere. The eventual end product of reactive bromine chemistry is HBr that is then deposited over a wide region, enhancing bromide in inland snow samples. Although frost flowers or open leads are likely to be the original source of halides that become reactive halogen gases, we find that the bromide release often occurs subsequent to production of aerosol from marine sources. |
| Programme |
437 |
| 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 |
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Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5598 |
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| Author |
Marchaudon, A.; Cerisier, J.-C.; Greenwald, R.A.; Sofko, G.J. |
| Title |
Electrodynamics of a flux transfer event: Experimental test of the Southwood model |
Type |
Journal Article |
| Year |
2004 |
Publication |
Geophysical research letters |
Abbreviated Journal |
|
| Volume |
31 |
Issue |
|
Pages |
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| Keywords |
2409 Ionosphere: Current systems; 2431 Ionosphere: Ionosphere/magnetosphere interactions; 2463 Ionosphere: Plasma convection; 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions |
| Abstract |
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| Programme |
312;911 |
| 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 |
5587 |
| Permanent link to this record |
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| Author |
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| Title |
Modeling the lithospheric magnetic field over France by means of revised spherical cap harmonic analysis (R-SCHA) |
Type |
Journal Article |
| Year |
2006 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
| Volume |
111 |
Issue |
|
Pages |
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| Keywords |
regional modeling; France; magnetic field; 1517 Geomagnetism and Paleomagnetism: Magnetic anomalies: modeling and interpretation; 1545 Geomagnetism and Paleomagnetism: Spatial variations: all harmonics and anomalies; 0545 Computational Geophysics: Modeling |
| Abstract |
We have recently proposed the revised spherical cap harmonic analysis (R-SCHA) modeling technique. The new mathematical functions represent faithfully the spatial variations of potential fields in a restricted area. In this paper, we tackle the inverse problem and outline the efficiency of the new basis functions with respect to real magnetic data. Processing simultaneously repeat stations, observatory, aeromagnetic, and CHAMP satellite data provides our first vector lithospheric field model over France, which extends from surface to 500 km of altitude. The magnetic field is represented with a minimum horizontal spatial representation of 40 km at the mean Earth radius. The magnetic lithospheric map consistency is confirmed with a comparison to known geological features. The model variation with altitude also suggests that the major French magnetic anomaly, the Paris basin anomaly, is produced by a deep-rooted geological structure. These results demonstrate the superiority of regional modeling over global modeling for delineating small-scale details in the lithospheric field. In view of forthcoming satellite missions, like Swarm, the revised spherical cap harmonic analysis method will help to accurately represent the lithospheric field for more detailed geological interpretations. |
| Programme |
905;139 |
| 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 |
5617 |
| Permanent link to this record |
