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Author |
Baroni, M.; Thiemens, M.H.; Delmas, R.J.; Savarino, J. |
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Title |
Mass-Independent Sulfur Isotopic Compositions in Stratospheric Volcanic Eruptions |
Type |
Journal Article |
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Year |
2007 |
Publication |
Science |
Abbreviated Journal |
Science |
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Volume |
315 |
Issue |
5808 |
Pages |
84-87 |
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Abstract |
The observed mass-independent sulfur isotopic composition ({Delta}33S) of volcanic sulfate from the Agung (March 1963) and Pinatubo (June 1991) eruptions recorded in the Antarctic snow provides a mechanism for documenting stratospheric events. The sign of {Delta}33S changes over time from an initial positive component to a negative value. {Delta}33S is created during photochemical oxidation of sulfur dioxide to sulfuric acid on a monthly time scale, which indicates a fast process. The reproducibility of the results reveals that {Delta}33S is a reliable tracer to chemically identify atmospheric processes involved during stratospheric volcanism. |
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457;1011 |
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0036-8075 |
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10.1126/science.1131754 |
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yes |
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Call Number  |
IPEV @ Thierry.Lemaire @ |
Serial |
5612 |
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Author |
Verhoeven, O.; Rivoldini, A.; Vacher, P.; Mocquet, A.; Choblet, G.; Menvielle, M.; Dehant, V.; Van Hoolst, T.; Sleewaegen, J.; Barriot, J.-P.; Lognonné, P. |
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Title |
Interior structure of terrestrial planets: Modeling Mars' mantle and its electromagnetic, geodetic, and seismic properties |
Type |
Journal Article |
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Year |
2005 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
110 |
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Keywords |
internal structure; Mars; network science; 5430 Planetary Sciences: Solid Surface Planets: Interiors; 6225 Planetary Sciences: Solar System Objects: Mars; 3672 Mineralogy and Petrology: Planetary mineralogy and petrology |
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Abstract |
We present a new procedure to describe the one-dimensional thermodynamical state and mineralogy of any Earth-like planetary mantle, with Mars as an example. The model parameters are directly related to expected results from a geophysical network mission, in this case electromagnetic, geodetic, and seismological processed observations supplemented with laboratory measurements. We describe the internal structure of the planet in terms of a one-dimensional model depending on a set of eight parameters: for the crust, the thickness and the mean density, for the mantle, the bulk volume fraction of iron, the olivine volume fraction, the pressure gradient, and the temperature profile, and for the core, its mass and radius. Currently, available geophysical and geochemical knowledge constrains the range of the parameter values. In the present paper, we develop the forward problem and present the governing equations from which synthetic data are computed using a set of parameter values. Among all Martian models fitting the currently available knowledge, we select eight candidate models for which we compute synthetic network science data sets. The synergy between the three geophysical experiments of electromagnetic sounding, geodesy, and seismology is emphasized. The stochastic inversion of the synthetic data sets will be presented in a companion paper. |
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Programme |
905;907 |
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Bachelor's thesis |
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American Geophysical Union |
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0148-0227 |
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yes |
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IPEV @ Thierry.Lemaire @ |
Serial |
5567 |
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Author |
Callot, J.-P.; Geoffroy, L.; Brun, J.-P. |
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Title |
Development of volcanic passive margins: Three-dimensional laboratory models |
Type |
Journal Article |
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Year |
2002 |
Publication |
Tectonics |
Abbreviated Journal |
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Volume |
21 |
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Keywords |
8109 Tectonophysics: Continental tectonics—extensional; 8120 Tectonophysics: Dynamics of lithosphere and mantle—general; 8159 Tectonophysics: Rheology—crust and lithosphere; 8194 Tectonophysics: Instruments and techniques |
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Abstract |
Continental breakup above an anomalously hot mantle may lead to the development of volcanic margins. Volcanic margins are characterized by (1) thick seaward dipping lava flow sequences, (2) central intrusive complexes associated with dyke swarms parallel to the coast, and (3) high seismic velocity bodies in the lower crust attributable to magma underplating. A conceptual model for volcanic margins development has recently been proposed based on onshore studies of the Greenland margins and the British Tertiary Igneous Province. It is proposed that the long-lived central intrusions are genetically linked to underlying persistent zones of mantle fusion. These localized melting domains (or soft spots), equivalent to small mantle diapirs, may locally soften the extending continental lithosphere. The low-viscosity diapirs would (1) localize tectonic strain and (2) feed the volcanic margin with magma. Thus such soft spots can control the along-strike magmatic and tectonic segmentation of volcanic margins. Recent geophysical investigations appear to show that the along-strike structure of volcanic passive margins is compatible with such a segmentation process. Here we present a set of scaled experiments designed to study how such localized rheological heterogeneities in the sub-Moho mantle may have a mechanical effect on continental breakup. Four-layer models were constructed using sand and silicone putties to represent the brittle and ductile layers of both crust and mantle. The soft spots are simulated by low-viscosity silicone putty emplaced within the brittle material. At the scale of the entire breakup zone, the soft spots display an oceanic-type strength profile defining low-strength zones where continental breakup is initiated. The rift orientation and segmentation are strongly controlled by the distribution of the low-viscosity heterogeneities, rather than by the direction of regional extension. The experiments are compared with the geometry and segmentation of the onshore part of the Greenland volcanic margins. |
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Programme |
290 |
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American Geophysical Union |
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0278-7407 |
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yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5547 |
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Author |
Sarti, P.; Negusini, M.; Lanconelli, C.; Lupi, A.; Tomasi, C.; Cacciari, A. |
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Title |
GPS and Radiosonde Derived Precipitable Water Vapour Content and its Relationship with 5 Years of Long-Wave Radiation Measurements at “Mario Zucchelli” Station, Terra Nova Bay, Antarctica |
Type |
Book Chapter |
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Year |
2008 |
Publication |
Geodetic and Geophysical Observations in Antarctica |
Abbreviated Journal |
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Pages |
145-177 |
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Abstract |
The Italian “Mario Zucchelli” Station (-74° 41? 55??.6997 N, 164° 06? 10??. 5887 E), situated at Terra Nova Bay, Northern Victoria Land, is equipped with a permanent Global Positioning System receiver (TNB1), continuously observing since 1998. “Mario Zucchelli” is an Antarctic experimental facility where a large number of scientific observations are carried out, either permanently or seasonally. In particular, an observatory devoted to atmospheric physics is located at Campo Icaro, 2.5 km from the base: it is a Clean Air Facility where several atmospheric measurements are carried out. Since 2000, long-wave radiation measurements are performed routinely using a Kipp&Zonen CNR-1 net radiometer. The GPS data set acquired over a six-year period spanning 2000–2005 by the permanent GPS station TNB1 is here analyzed, with the aim of retrieving the Precipitable Water (PW) content. Water vapour radiative effects on the thermal radiation balance of the atmosphere are of basic importance for the energy budget of the surface-atmosphere system in Antarctica, even though Precipitable Water assumes in general appreciably lower values than in other areas of our planet. Therefore, precise calculations and measurements of the mean long-wave radiation flux density reaching the surface at Terra Nova Bay are presented as a function of Precipitable Water, to give evidence of the relationship existing between this radiative balance term and the total atmospheric content of water vapour. The GPS-derived PW values are compared with radiosonde-derived PW values measured at Terra Nova Bay. The radiosounding data were analyzed by correcting the temperature data for the errors due to radiation and heat exchange processes and lag effects; the air relative humidity data were corrected for the errors and various dry bias following an accurate procedure recently developed by Tomasi et al. (2006) to reduce the errors and bias affecting the moisture measurements. The analysis strategies that have been applied to GPS and radiosonde data sets for computing PW are presented, including (i) the relation between the measured radiant-flux density and the GPS-derived PW, and (ii) the comparison with the predicted radiant-flux density derived by a model with five different profiles of temperature and humidity, computed from the set of radiosoundings performed at Terra Nova Bay. GPS- and radiosonde-derived water vapour contents at Terra Nova Bay show a good agreement over the whole sample period, with small discrepancies that will be opportunely discussed. |
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1176 |
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yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5516 |
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Author |
Petkov, B.; Vitale, V.; Tomasi, C.; Bonaf, U.; Scaglione, S.; Flori, D.; Santaguida, R.; Gausa, M.; Hansen, G.; Colombo, T. |
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Title |
Narrowband filter radiometer for ground-based measurements of global ultraviolet solar irradiance and total ozone |
Type |
Journal Article |
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Year |
2006 |
Publication |
Applied optics |
Abbreviated Journal |
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Volume |
45 |
Issue |
18 |
Pages |
4383-4395 |
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Keywords |
Atmospheric optics; Ozone; Instrumentation, measurement, and metrology |
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Abstract |
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Programme |
1176 |
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Publisher |
OSA |
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ISSN |
0003-6935 |
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yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5517 |
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Author |
Jourdain, B.; Legrand, M. |
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Title |
Year-round records of bulk and size-segregated aerosol composition and HCl and HNO3 levels in the Dumont d'Urville (coastal Antarctica) atmosphere: Implications for sea-salt aerosol fractionation in the winter and summer |
Type |
Journal Article |
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Year |
2002 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
107 |
Issue |
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Pages |
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Keywords |
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 |
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Abstract |
Year-round composition of bulk and size-segregated aerosol was examined at a coastal Antarctic site (Dumont d'Urville). Sea-salt particles display a summer depletion of chloride relative to sodium, which reaches ?10%. The mass chloride loss is maximum on 1- to 3-?m-diameter particles, nitrate being often the anion causing the chloride loss. The summer SO42?/Na+ ratio exceeds the seawater value on submicron particles due to biogenic sulfate and on coarse particles due to ornithogenic (guano-enriched soils) sulfate and to heterogeneous uptake of SO2 (or H2SO4). HCl levels range from 47 ± 28 ng m?3 in the winter to 130 ± 110 ng m?3 in the summer, being close to the mass chloride loss of sea-salt aerosols. In the winter, sea-salt particles exhibit Cl?/Na+ and SO42?/Na+ mass ratios of 1.9 ± 0.1 and 0.13 ± 0.04, respectively. Resulting from precipitation of mirabilite during freezing of seawater, this sulfate-depletion-relative sodium takes place from May to October. From March to April, warmer temperatures and/or smaller sea ice extent offshore the site limit the phenomenon. A range of 14–50 ng m?3 of submicron sulfate is found, confirming the existence of nssSO42? in the winter at a coastal Antarctic site, highest values being found in the winters of 1992–1994 due to the Pinatubo volcanic input. Apart from these three winters, nssSO42? levels range between 15 and 30 ng m?3, but its origin is still unclear (quasi-continuous SO2 emissions from the Mount Erebus volcano or local wintertime dimethyl sulfide [DMS] oxidation, in addition to long-range transported by-product of DMS oxidation). |
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414 |
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Publisher |
American Geophysical Union |
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0148-0227 |
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yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5646 |
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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. |
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Title |
Diurnal production of gaseous mercury in the alpine snowpack before snowmelt |
Type |
Journal Article |
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Year |
2007 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
112 |
Issue |
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Pages |
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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 |
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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. |
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399 |
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Publisher |
American Geophysical Union |
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0148-0227 |
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yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5568 |
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Author |
Mahowald, N.M.; Rasch, P.J.; Eaton, B.E.; Whittlestone, S.; Prinn, R.G. |
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Title |
Transport of 222radon to the remote troposphere using the Model of Atmospheric Transport and Chemistry and assimilated winds from ECMWF and the National Center for Environmental Prediction/NCAR |
Type |
Journal Article |
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Year |
0 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
102 |
Issue |
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Abstract |
The Model of Atmospheric Transport and Chemistry (MATCH) is used to simulate the transport of 222Rn using both European Centre for Medium-Range Weather Forecasts (ECMWF) winds and National Center for Environmental Prediction/National Center for Atmospheric Research (hereafter referred to as NCEP) reanalysis winds. These winds have the advantage of being based on observed winds but have the disadvantage that the subgrid-scale transport processes are not routinely archived. MATCH derives subgrid-scale mixing rates for the boundary layer using a nonlocal scheme and for moist convective mixing using one of two parameterizations (Tiedtke [1989] or Pan and Wu [1997]). This paper describes the ability of the model to recreate mixing rates of 222Rn using the forecast center winds. Radon 222 is a species with a continental crust source and a simple sink involving radioactive decay with an e-folding timescale of 5.5 days. This atmospheric constituent is therefore a good tracer for testing the vertical transport in the chemical transport model, as well as the horizontal transport from continental regions to remote oceanic regions. The various simulations of 222Rn are compared with observations as well as with each other, allowing an estimate of the uncertainty in transport due to uncertainties in the winds and subgrid-scale processes. The calculated vertical profiles over the western United States are somewhat similar to observed, and the upper tropospheric concentrations compare reasonably well in their spatial distribution with data collected during Tropospheric Ozone II (TROPOZ II), although the model values tend to be higher than observed values, especially in the upper troposphere. The model successfully simulates specific observed pollution events at Cape Grim. It has more difficulty at sites farther from continental source regions, although the model captures the seasonal structure of the pollution events at these sites (Macquarie Island, Amsterdam Island, Kerguelen Island, and Crozet Island). Inclusion of a moist convective mixing scheme in MATCH increases 222Rn concentrations in the upper troposphere by 50% compared to not having moist convective mixing, while surface concentrations do not appear to be very sensitive to moist convection. In addition, differences between the upper tropospheric concentrations of radon predicted using the ECMWF and NCEP winds can be 30% for large areas of the globe, due to either differences in the forecast center winds themselves or the moist convective mixing schemes used in conjunction with them. This has implications for model simulations of radiatively and chemically important trace species in the atmosphere. |
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Programme |
146 |
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Publisher |
American Geophysical Union |
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0148-0227 |
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yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5541 |
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Author |
Röthlisberger, R.; Mulvaney, R.; Wolff, E.W.; Hutterli, M.A.; Bigler, M.; Sommer, S.; Jouzel, J. |
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Title |
Dust and sea salt variability in central East Antarctica (Dome C) over the last 45 kyrs and its implications for southern high-latitude climate |
Type |
Journal Article |
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Year |
2002 |
Publication |
Geophysical research letters |
Abbreviated Journal |
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Volume |
29 |
Issue |
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Pages |
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Keywords |
3344 Meteorology and Atmospheric Dynamics: Paleoclimatology; 1620 Global Change: Climate dynamics; 9310 Information Related to Geographic Region: Antarctica; 0368 Atmospheric Composition and Structure: Troposphere—constituent transport and chemistry |
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Abstract |
A detailed record of non-sea-salt calcium, a proxy for dust, and sea-salt sodium, a proxy for sea salt, covering the last 45 kyr is presented. It shows that in the first part of the transition from the last glacial period to the Holocene (18–15 kyr BP), the changes in dust flux mainly reflect changes at the dust source, namely vegetation cover and local climate. The changes in the later part of the transition (12–11 kyr BP) are similar in extent to the changes seen in sea salt and most likely reflect a reorganization of the atmospheric circulation. During the last glacial period, considerable variation of dust but not of sea salt is observed, pointing to climatic changes in Patagonia, the main dust source for Dome C. A comparison of the glacial records from Dome C and Taylor Dome suggests that similar influences controlled aerosol input at both sites during this period. |
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Programme |
960 |
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American Geophysical Union |
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0094-8276 |
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yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5584 |
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Author |
McCabe, J.R.; Thiemens, M.H.; Savarino, J. |
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Title |
A record of ozone variability in South Pole Antarctic snow: Role of nitrate oxygen isotopes |
Type |
Journal Article |
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Year |
2007 |
Publication |
Journal of geophysical research-atmospheres |
Abbreviated Journal |
J. Geophys. Res. |
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Volume |
112 |
Issue |
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Pages |
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Keywords |
nitrate; isotopes; ozone; 1041 Geochemistry: Stable isotope geochemistry; 0305 Atmospheric Composition and Structure: Aerosols and particles; 3344 Atmospheric Processes: Paleoclimatology; 1610 Global Change: Atmosphere; 0776 Cryosphere: Glaciology |
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Abstract |
The information contained in polar nitrate has been an unresolved issue for over a decade. Here we demonstrate that atmospheric nitrate's oxygen isotopic composition (?17O-NO3) reflects stratospheric chemistry in winter and tropospheric chemistry in summer. Surface snow isotope mass balance indicates that nitrate oxygen isotopic composition is the result of a mixture of 25% stratospheric and 75% tropospheric origin. Analysis of trends in ?17O-NO3 in a 6 m snow pit that provides a 26-year record reveals a strong 2.70-year cycle that anticorrelates (R = ?0.77) with October–November–December column ozone. The potential mechanisms linking the records are either denitrification or increased boundary layer photochemical ozone production. We suggest that the latter is dominating the observed trend and find that surface ozone and ?17O-NO3 correlate well before 1991 (R = 0.93). After 1991, however, the records show no significant relationship, indicating an altered oxidative environment consistent with current understanding of a highly oxidizing atmosphere at the South Pole. The disappearance of seasonal ?17O-NO3 trends in the surface layer at depth remain unresolved and demand further investigation of how postdepositional processes affect nitrate's oxygen isotope composition. Overall, the findings of this study present a new paleoclimate technique to investigate Antarctic nitrate records that appear to reflect trends in stratospheric ozone depletion by recording tropospheric surface ozone variability. |
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1011 |
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American Geophysical Union |
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0148-0227 |
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yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
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5510 |
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