| Records |
| Author |
Spracklen, D.V.; Arnold, S.R.; Sciare, J.; Carslaw, K.S.; Pio, C. |
| Title |
Globally significant oceanic source of organic carbon aerosol |
Type |
Journal Article |
| Year |
2008 |
Publication |
Geophysical research letters |
Abbreviated Journal |
|
| Volume |
35 |
Issue |
|
Pages |
|
| Keywords |
organic carbon; ocean; aerosol; 0305 Atmospheric Composition and Structure: Aerosols and particles; 0315 Atmospheric Composition and Structure: Biosphere/atmosphere interactions; 0312 Atmospheric Composition and Structure: Air/sea constituent fluxes |
| Abstract |
Significant concentrations of organic carbon (OC) aerosol are observed at three oceanic surface sites (Amsterdam Island, Azores and Mace Head). Two global chemical transport models (CTMs) underpredict OC concentrations at these sites (normalised mean bias of ?67% and ?58%). During periods of high biological activity monthly mean concentrations are underpredicted by a factor of 5–20. At Amsterdam Island and Mace Head, observed OC correlates well (R2 = 0.61–0.77) with back-trajectory weighted chlorophyll-a, suggesting an oceanic OC source driven by biological activity. We use a combination of remote sensed chlorophyll-a, back trajectories and observed OC to derive an empirical relation between chlorophyll-a and the total oceanic OC emission flux. Using the GEOS-chem CTM we show a global oceanic OC emission, from primary and secondary sources, of ?8 Tg/year matches observations. This emission is comparable in magnitude to the fossil fuel OC source and increases the simulated global OC burden by 20%. |
| Programme |
414;415 |
| Campaign |
|
| Address |
|
| Corporate Author |
|
Thesis |
Bachelor's thesis |
| Publisher |
American Geophysical Union |
Place of Publication |
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Editor |
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| Language |
|
Summary Language |
|
Original Title |
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| Series Editor |
|
Series Title |
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Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0094-8276 |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5523 |
| Permanent link to this record |
| |
|
| |
| Author |
Thébault, E.; Gaya-Piqué, L. |
| Title |
Applied comparisons between SCHA and R-SCHA regional modeling techniques |
Type |
Journal Article |
| Year |
2008 |
Publication |
Geochem. Geophys. Geosyst. |
Abbreviated Journal |
|
| Volume |
9 |
Issue |
|
Pages |
|
| Keywords |
regional modeling; SCHA; R-SCHA; 1517 Geomagnetism and Paleomagnetism: Magnetic anomalies: modeling and interpretation; 1541 Geomagnetism and Paleomagnetism: Satellite magnetics: main field, crustal field, external field |
| Abstract |
Spherical cap harmonic analysis (SCHA) has become a common tool for the regional modeling of potential fields since its introduction by Haines (1985). The fact that SCHA satisfies Laplace equation and the possibility of representing high-frequency fields with a small number of coefficients (compared to the global spherical harmonic analysis) made SCHA the preferred choice for the development, for example, of magnetic field models at national scale. However, Thébault et al. (2006a) demonstrated that the traditional SCHA presented some deficiencies, in particular related to the inversion of multilevel data sets. The authors presented the R-SCHA technique as an alternative method in which the introduction of a new set of basis functions and boundary conditions solved this issue. In this paper we present some numerical comparisons between the SCHA and R-SCHA techniques applied with different synthetic vector data sets, from near-surface main field, main difference, and crustal field data simulating a World Digital Magnetic Anomaly Map subset. Other analyses are carried out with synthetic vector data set that mimics the expected data distribution from a multisatellite mission like the forthcoming European Swarm mission. No regularization, weighting, or ad hoc procedures are applied to the synthetic vector data, and a cap of 7° aperture is considered. The numerical analyses show that SCHA is a satisfying approximation in a band-limited spectral region that depends on the cap's size. It does not work correctly either for main field or for the short-scale crustal field modeling. These aspects are supported by equations illustrating why SCHA may fail. On the contrary, R-SCHA converges more slowly than SCHA but is valid in all cases. It gives a consistent set of regional coefficients and fits the radial variation of the field in a realistic way. At last, the special case of data incompatibility shows that R-SCHA does not fit incompatible data while SCHA assimilates most of them. These results should help the scientific community to evaluate the level of approximation needed for the development of regional magnetic field models in the era of the European Space Agency Swarm mission. |
| Programme |
139 |
| 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 |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
1525-2027 |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5527 |
| Permanent link to this record |
| |
|
| |
| Author |
Faccenna, C.; Rossetti, F.; Becker, T.W.; Danesi, S.; Morelli, A. |
| Title |
Recent extension driven by mantle upwelling beneath the Admiralty Mountains (East Antarctica) |
Type |
Journal Article |
| Year |
2008 |
Publication |
Tectonics |
Abbreviated Journal |
|
| Volume |
27 |
Issue |
|
Pages |
|
| Keywords |
Antarctica; continental tectonics; faulting; mantle dynamics; seismic tomography; 7230 Seismology: Seismicity and tectonics; 8010 Structural Geology: Fractures and faults; 8107 Tectonophysics: Continental neotectonics; 7270 Seismology: Tomography; 8122 Tectonophysics: Dynamics: gravity and tectonics |
| Abstract |
Northern Victoria Land is located at the boundary between an extended, presumably hot, region (West Antarctic Rift System) and the thick, possibly cold, East Antarctic craton. The style and timing of Tertiary deformation along with relationships with the magmatic activity are still unclear, and contrasting models have been proposed. We performed structural and morphotectonic analyses at the NE termination of northern Victoria Land in the Admiralty Mountains area, where the relationship between topography, tectonics, and magmatism is expected to be well pronounced. We found evidence of two subsequent episodes of faulting, occurring concurrently with the Neogene McMurdo volcanism. The first episode is associated with dextral transtension, and it is overprinted by extensional tectonics during the emplacement of large shield alkaline volcanoes. Upper mantle seismic tomography shows that the extensional regime is limited to regions overlying a low-velocity anomaly. We interpret this anomaly to be of thermal origin, and have tested the role of large-scale upwelling on lithosphere deformation in the area. The results of this integrated analysis suggest that the morphotectonic setting of the region and the magmatism is likely the result of upwelling flow at the boundary between the cold cratonic and the hot stretched province (WARS), at work until recent time in this portion of the northern Victoria Land. |
| Programme |
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 |
0278-7407 |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5551 |
| Permanent link to this record |
| |
|
| |
| Author |
Biessy, G.; Dauteuil, O.; Van Vliet-Lanoë, B.; Wayolle, A. |
| Title |
Fast and partitioned postglacial rebound of southwestern Iceland |
Type |
Journal Article |
| Year |
2008 |
Publication |
Tectonics |
Abbreviated Journal |
|
| Volume |
27 |
Issue |
|
Pages |
|
| 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 |
| 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. |
| Programme |
316 |
| 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 |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0278-7407 |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5569 |
| Permanent link to this record |
| |
|
| |
| Author |
Jourdain Bruno, Preunkert Susanne, Cerri Omar, Castebrunet Hlne, Udisti Roberto, Legrand Michel, |
| Title |
Year-round record of size-segregated aerosol composition in central Antarctica (Concordia station): Implications for the degree of fractionation of sea-salt particles
|
Type |
Journal Article |
| Year |
2008 |
Publication |
J. Geophys. Res. |
Abbreviated Journal |
J. Geophys. Res. |
| Volume |
113 |
Issue |
D14 |
Pages |
D14308 - |
| Keywords |
Central Antarctica, size segregated aerosol, sea-salt fractionation, 0305 Atmospheric Composition and Structure: Aerosols and particles, 0345 Atmospheric Composition and Structure: Pollution: urban and regional, 4801 Oceanography: Biological and Chemical: Aerosols, 4906 Paleoceanography: Aerosols, 0368 Atmospheric Composition and Structure: Troposphere: constituent transport and chemistry, 9310 Geographic Location: Antarctica, 4207 Oceanography: General: Arctic and Antarctic oceanography, 3300 Atmospheric Processes, |
| Abstract |
The origin of sea-salt aerosol that reaches the high Antarctic plateau and is trapped in snow and ice cores remains still unclear. In particular, the respective role of emissions from the open ocean versus those from the sea-ice surface is not yet quantified. To progress on this question, the composition of bulk and size-segregated aerosol was studied in 2006 at the Concordia station (75S, 123E) located on the high Antarctic plateau. A depletion of sulfate relative to sodium with respect to the seawater composition is observed on sea-salt aerosol reaching Concordia from April to September. That suggests that in winter, when the sea-salt atmospheric load reaches a maximum, emissions from the sea-ice surface significantly contribute to the sea-salt budget of inland Antarctica.
|
| Programme |
414;903;1181 |
| Campaign |
|
| Address |
|
| Corporate Author |
|
Thesis |
Bachelor's thesis |
| Publisher |
AGU |
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 |
|
Serial |
1693 |
| Permanent link to this record |
| |
|
| |
| Author |
Celarier, E. A., E. J. Brinksma, J. F. Gleason, J. P. Veefkind, A. Cede, J. R. Herman, D. Ionov, F. Goutail, J.-P. Pommereau, J.-C. Lambert, M. van Roozendael, G. Pinardi, F. Wittrock, A. Schönhardt, A. Richter, O. W. Ibrahim, T. Wagner, B. Bojkov, G. Mou |
| Title |
Validation of Ozone Monitoring Instrument nitrogen dioxide columns |
Type |
Journal Article |
| Year |
2008 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
| Volume |
113 |
Issue |
|
Pages |
D15S15 |
| Keywords |
|
| Abstract |
|
| Programme |
209 |
| Campaign |
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| Address |
|
| Corporate Author |
|
Thesis |
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| Publisher |
|
Place of Publication |
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Editor |
|
| Language |
|
Summary Language |
|
Original Title |
|
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0148-0227 |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
yes |
| Call Number |
|
Serial |
5298 |
| Permanent link to this record |
| |
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| |
| Author |
Faïn, X.; Grangeon, S.; Bahlmann, E.; Fritsche, J.; Obrist, D.; Dommergue, A.; Ferrari, C.P.; Cairns, W.; Ebinghaus, R.; Barbante, C.; Cescon, P.; Boutron, C. |
| Title |
Diurnal production of gaseous mercury in the alpine snowpack before snowmelt |
Type |
Journal Article |
| Year |
2007 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
| Volume |
112 |
Issue |
|
Pages |
|
| Keywords |
Gaesous mercury; snow; flux; 0330 Atmospheric Composition and Structure: Geochemical cycles; 0322 Atmospheric Composition and Structure: Constituent sources and sinks; 1863 Hydrology: Snow and ice |
| Abstract |
In March 2005, an extensive mercury study was performed just before snowmelt at Col de Porte, an alpine site close to Grenoble, France. Total mercury concentration in the snowpack ranged from 80 ± 08 to 160 ± 15 ng l?1, while reactive mercury was below detection limit (0.2 ng l?1). We observed simultaneously a production of gaseous elemental mercury (GEM) in the top layer of the snowpack and an emission flux from the snow surface to the atmosphere. Both phenomena were well correlated with solar irradiation, indicating photo-induced reactions in the snow interstitial air (SIA). The mean daily flux of GEM from the snowpack was estimated at ?9 ng m?2 d?1. No depletion of GEM concentrations was observed in the SIA, suggesting no occurrence of oxidation processes. The presence of liquid water in the snowpack clearly enhanced GEM production in the SIA. Laboratory flux chamber measurements enabled us to confirm that GEM production from this alpine snowpack was first driven by solar radiation (especially UVA and UVB radiation), and then by liquid water in the snowpack. Finally, a large GEM emission from the snow surface occurred during snowmelt, and we report total mercury concentrations in meltwater of about 72 ng l?1. |
| Programme |
399 |
| Campaign |
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| Address |
|
| Corporate Author |
|
Thesis |
|
| Publisher |
American Geophysical Union |
Place of Publication |
|
Editor |
|
| Language |
|
Summary Language |
|
Original Title |
|
| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0148-0227 |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5568 |
| Permanent link to this record |
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| |
| Author |
Dalton Colleen A, Ekstrm Gran, Dziewoski Adam M, |
| Title |
The global attenuation structure of the upper mantle
|
Type |
Journal Article |
| Year |
2008 |
Publication |
J. Geophys. Res. |
Abbreviated Journal |
J. Geophys. Res. |
| Volume |
113 |
Issue |
B9 |
Pages |
B09303- |
| Keywords |
Attenuation, surface waves, global seismology, 7270 Seismology: Tomography, 7260 Seismology: Theory, 7208 Seismology: Mantle, 3909 Mineral Physics: Elasticity and anelasticity, 8124 Tectonophysics: Earth's interior: composition and state, |
| Abstract |
A large data set of fundamental mode Rayleigh wave amplitudes is analyzed to derive a new global three-dimensional model of shear wave attenuation in the upper mantle. The amplitude observations span a range of periods between 50 and 250 s and are derived from earthquakes with M W > 6.0 that occurred between 1993 and 2005. Four separate factors may influence an amplitude anomaly: intrinsic attenuation along the raypath, elastic focusing effects along the raypath, uncertainties in the strength of excitation, and uncertainties in the response at the station. In an earlier paper (Dalton and Ekstrm, 2006a), dependence of the retrieved attenuation structure on these terms was shown to be significant and an approach was developed to invert the amplitudes simultaneously for each term. The new three-dimensional attenuation model QRFSI12, which is the subject of this paper, is derived using this method. The model contains large lateral variations in upper-mantle attenuation, 60% to 100%, and exhibits strong agreement with surface tectonic features at depths shallower than 200 km. At greater depth, QRFSI12 is dominated by high attenuation in the southeastern Pacific and eastern Africa and low attenuation along many subduction zones in the western Pacific. Resolution tests confirm that the change in pattern of attenuation above and below 200-km depth can be determined with confidence using the fundamental mode data set. The new model is highly correlated with global models of shear wave velocity, particularly in the uppermost mantle, suggesting that the same factors may control both seismic attenuation and velocity in this depth range. However, forcing the lateral perturbations in attenuation to match those found in global velocity models decreases the data variance reduction, which suggests that subtle differences between patterns of attenuation and velocity are robust.
|
| Programme |
133 |
| Campaign |
|
| Address |
|
| Corporate Author |
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Thesis |
Bachelor's thesis |
| Publisher |
AGU |
Place of Publication |
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Editor |
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| Language |
|
Summary Language |
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Original Title |
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| Series Editor |
|
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 |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
yes |
| Call Number |
|
Serial |
2785 |
| Permanent link to this record |
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| |
| Author |
Gaya-Piqué, L.R.; Curto, J.J.; Torta, J.M.; Chulliat, A. |
| Title |
Equivalent ionospheric currents for the 5 December 2006 solar flare effect determined from spherical cap harmonic analysis |
Type |
Journal Article |
| Year |
2008 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
| Volume |
113 |
Issue |
|
Pages |
|
| Keywords |
solar flare effects; SCHA; magnetic observatories; 1530 Geomagnetism and Paleomagnetism: Rapid time variations; 2409 Ionosphere: Current systems; 2447 Ionosphere: Modeling and forecasting; 7974 Space Weather: Solar effects; 0545 Computational Geophysics: Modeling |
| Abstract |
In this paper we analyze the prompt solar flare effect (SFE) associated to a strong X-ray flare that occurred on 5 December 2006 by using spherical cap harmonic analysis applied to the variations recorded in the European magnetic observatories network. The regional model allows the simultaneous modeling in space and time of the ionospheric equivalent current system responsible for the SFE, as well as for the regular diurnal variation S R on that day. It is found that the SFE equivalent current system does not form as an enhancement of the S R system. Its focus is distinct from that of the SR, and it is located between 3 and 10° higher in latitude and circa 40 min later in local time. |
| Programme |
139 |
| Campaign |
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| Address |
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| Corporate Author |
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Thesis |
|
| Publisher |
American Geophysical Union |
Place of Publication |
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Editor |
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| Language |
|
Summary Language |
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Original Title |
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| Series Editor |
|
Series Title |
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Abbreviated Series Title |
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| Series Volume |
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Series Issue |
|
Edition |
|
| ISSN |
0148-0227 |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5498 |
| Permanent link to this record |
| |
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| |
| Author |
Montagner, J.-P.; Marty, B.; Stutzmann, E.; Sicilia, D.; Cara, M.; Pik, R.; Lévêque, J.-J.; Roult, G.; Beucler, E.; Debayle, E. |
| Title |
Mantle upwellings and convective instabilities revealed by seismic tomography and helium isotope geochemistry beneath eastern Africa |
Type |
Journal Article |
| Year |
2007 |
Publication |
Geophysical research letters |
Abbreviated Journal |
|
| Volume |
34 |
Issue |
|
Pages |
|
| Keywords |
anisotropy tomography; helium isotope data; Africa; 8121 Tectonophysics: Dynamics: convection currents, and mantle plumes; 7270 Seismology: Tomography; 1040 Geochemistry: Radiogenic isotope geochemistry; 7208 Seismology: Mantle; 9305 Geographic Location: Africa |
| Abstract |
The relationship between intraplate volcanism and continental tectonics has been investigated for North and East Africa using a high resolution three-dimensional anisotropic tomographic model derived from seismic data of a French experiment “Horn of Africa” and existing broadband data. The joint inversion for seismic velocity and anisotropy of the upper 400 km of the mantle, and geochemical data reveals a complex interaction between mantle upwellings, and lithosphere. Two kinds of mantle upwellings can be distinguished: The first one, the Afar “plume” originates from deeper than 400 km and is characterized by enrichment in primordial 3He and 3He/4He ratios higher than those along mid-ocean ridges (MOR). The second one, associated with other Cenozoic volcanic provinces (Darfur, Tibesti, Hoggar, Cameroon), with 3He/4He ratios similar to, or lower than MOR, is a consequence of shallower upwelling. The presumed asthenospheric convective instabilities are oriented in an east-west direction, resulting from interaction between south-north asthenospheric mantle flow, main plume head and topography on the base of lithosphere. |
| Programme |
133;906 |
| Campaign |
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| Address |
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| Corporate Author |
|
Thesis |
|
| Publisher |
American Geophysical Union |
Place of Publication |
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Editor |
|
| Language |
|
Summary Language |
|
Original Title |
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| Series Editor |
|
Series Title |
|
Abbreviated Series Title |
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| Series Volume |
|
Series Issue |
|
Edition |
|
| ISSN |
0094-8276 |
ISBN |
|
Medium |
|
| Area |
|
Expedition |
|
Conference |
|
| Notes |
|
Approved |
yes |
| Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5511 |
| Permanent link to this record |
