Spracklen, D.V.; Arnold, S.R.; Sciare, J.; Carslaw, K.S.; Pio, C. (2008). Globally significant oceanic source of organic carbon aerosol. Geophysical research letters, 35.
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
Programme: 414;415
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. (2008). Applied comparisons between SCHA and R-SCHA regional modeling techniques. Geochem. Geophys. Geosyst., 9.
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
Programme: 139
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Faccenna, C.; Rossetti, F.; Becker, T.W.; Danesi, S.; Morelli, A. (2008). Recent extension driven by mantle upwelling beneath the Admiralty Mountains (East Antarctica). Tectonics, 27.
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.
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
Programme: 906
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. (2008). Fast and partitioned postglacial rebound of southwestern Iceland. Tectonics, 27.
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
Programme: 316
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Jourdain Bruno, Preunkert Susanne, Cerri Omar, Castebrunet Hlne, Udisti Roberto, Legrand Michel, . (2008). Year-round record of size-segregated aerosol composition in central Antarctica (Concordia station): Implications for the degree of fractionation of sea-salt particles
. J. Geophys. Res., 113(D14), D14308–.
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.
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,
Programme: 414;903;1181
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. (2008). Validation of Ozone Monitoring Instrument nitrogen dioxide columns. J. Geophys. Res., 113, D15S15.
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. (2007). Diurnal production of gaseous mercury in the alpine snowpack before snowmelt. J. Geophys. Res., 112.
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
Programme: 399
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Dalton Colleen A, Ekstrm Gran, Dziewoski Adam M, . (2008). The global attenuation structure of the upper mantle
. J. Geophys. Res., 113(B9), B09303–.
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.
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,
Programme: 133
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. (2008). Equivalent ionospheric currents for the 5 December 2006 solar flare effect determined from spherical cap harmonic analysis. J. Geophys. Res., 113.
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
Programme: 139
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. (2007). Mantle upwellings and convective instabilities revealed by seismic tomography and helium isotope geochemistry beneath eastern Africa. Geophysical research letters, 34.
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
Programme: 133;906
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