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Author |
Pazmiño, A.F.; Godin-Beekmann, S.; Ginzburg, M.; Bekki, S.; Hauchecorne, A.; Piacentini, R.D.; Quel, E.J. |
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Title |
Impact of Antarctic polar vortex occurrences on total ozone and UVB radiation at southern Argentinean and Antarctic stations during 1997–2003 period |
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 |
Issue |
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Pages |
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Keywords  |
polar ozone loss; UV radiation; polar vortex; 1610 Global Change: Atmosphere; 0341 Atmospheric Composition and Structure: Middle atmosphere: constituent transport and chemistry; 0340 Atmospheric Composition and Structure: Middle atmosphere: composition and chemistry |
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Abstract |
The evolution of total ozone and surface UV radiation over some stations in the southern region of South America and in Antarctica in relationship with polar vortex occurrences is analyzed using Total Ozone Mapping Spectrometer total ozone measurements and local surface UV data for the 1997–2003 period. The data are classified as a function of the position of the stations with respect to the polar vortex using equivalent latitude at 550 K isentropic level. The study of vortex occurrences showed that Ushuaia station (54.9°S) was located ?40% of the cases in the edge of the vortex and 5% inside the vortex core during the winter-spring period. Concerning the Marambio (62.2°S) and Dumont d'Urville (66.4°S) stations, located on the shore of the Antarctic continent, the analysis shows a zonal asymmetry with respect to the center of the vortex. Marambio is located around 60% of the time inside the vortex, while Dumont d'Urville is predominantly at the edge of or outside the vortex. The evolution of the equivalent latitude of the stations in the anomalous 2002 winter presents a different behavior with respect to other years in the 1997–2003 period. The persistence of the vortex core above the stations is in average 1.8 days over Ushuaia and 7.1 days over Marambio in October during the 1997–2003 period with corresponding mean total ozone columns of 208.2 and 181.4 Dobson units, respectively. When the stations are inside the vortex, the total ozone columns are generally larger at Ushuaia than at Marambio in October during the 1997–2003 period. Finally, the impact of ozone-depleted air mass occurrences on ultraviolet radiation is evaluated by relating total ozone and UV erythemal dose measured at the stations. Twofold or threefold UV dose increases were reached in the 55°–65° southern latitude region during vortex overpasses, reaching maximum UV dose around 5 kJ/m2. The average increase of UV dose could be computed at the stations considered in the study when the measurement sampling and the number of vortex occurrences was sufficient. An average increase of 67.6% of the erythemal UV dose was found in October at Ushuaia over the years 1997, 1998, and 2000. This value is strongly weighted by vortex occurrences over the station in 2000. At Marambio an average UV increase of 47.4% was found over the years 1999 and 2000. Midlatitude stations like Comodoro Rivadavia (45.8°S) are generally little affected by vortex intrusions. Nevertheless, the maximum UV dose can increase by more than 50% when the vortex passes over the station. |
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209 |
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American Geophysical Union |
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ISSN |
0148-0227 |
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yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5601 |
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Author |
Wittlinger Gérard, Farra Véronique, |
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Title |
Evidence of unfrozen liquids and seismic anisotropy at the base of the polar ice sheets
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Type |
Journal Article |
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Year |
2015 |
Publication |
Polar Science |
Abbreviated Journal |
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Volume |
9 |
Issue |
1 |
Pages |
66-79 |
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Keywords |
Polar ice, Seismic anisotropy, Unfrozen liquids, |
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Abstract |
We analyze seismic data from broadband stations located on the Antarctic and Greenland ice sheets to determine polar ice seismic velocities. P-to-S converted waves at the ice/rock interface and inside the ice sheets and their multiples (the P-receiver functions) are used to estimate in-situ P-wave velocity (Vp) and P-to-S velocity ratio (Vp/Vs) of polar ice. We find that the polar ice sheets have a two-layer structure; an upper layer of variable thickness (about 2/3 of the total thickness) with seismic velocities close to the standard ice values, and a lower layer of approximately constant thickness with standard Vp but ∼25% smaller Vs. The lower layer ceiling corresponds approximately to the −30 °C isotherm. Synthetic modeling of P-receiver functions shows that strong seismic anisotropy and low vertical S velocity are needed in the lower layer. The seismic anisotropy results from the preferred orientation of ice crystal c-axes toward the vertical. The low vertical S velocity may be due to the presence of unfrozen liquids resulting from premelting at grain joints and/or melting of chemical solutions buried in the ice. The strongly preferred ice crystal orientation fabric and the unfrozen fluids may facilitate polar ice sheet basal flow. |
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Programme |
133 |
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ISSN |
18739652 |
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yes |
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6151 |
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Author |
Park Young-Hyang, Durand Isabelle, Kestenare Elodie, Rougier Gilles, Zhou Meng, d'Ovidio Francesco, Cotté Cédric, Lee Jae-Hak, |
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Title |
Polar Front around the Kerguelen Islands: An up-to-date determination and associated circulation of surface/subsurface waters |
Type |
Book Chapter |
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Year |
2014 |
Publication |
Journal of Geophysical Research: Oceans |
Abbreviated Journal |
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Volume |
119 |
Issue |
10 |
Pages |
6575-6592 |
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Keywords |
Polar Front, Kerguelen, Southern Ocean, 4207 Arctic and Antarctic oceanography, 4528 Fronts and jets, |
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Abstract |
The circulation of iron-rich shelf waters around the Kerguelen Islands plays a crucial role for a climatically important, annually recurrent phytoplankton spring bloom over the sluggish shelf region and its downstream plume area along the Antarctic circumpolar flow. However, there is a long-standing confusion about the Polar Front (PF) in the Kerguelen region due to diverse suggestions in the literature for its geographical location with an extreme difference over 10° of latitude. Based on abundant historical hydrographic data, the in situ hydrographic and current measurements during the 2011 KEOPS2 cruise, satellite chlorophyll images, and altimetry-derived surface velocity fields, we determine and validate an up-to-date location of the PF around the Kerguelen Islands. Artificial Lagrangian particle trajectories computed from altimetric velocity time series are analyzed for the possible pathways and sources of different surface/subsurface waters advected into the chlorophyll bloom area east off the islands studied during the KEOPS2 cruise. The PF location determined as the northernmost boundary of the Winter Water colder than 2°C, which is also associated with a band of strong currents, appears to be primarily controlled by topography. The PF rounds the Kerguelen Islands from the south to deflect northward along the eastern escarpment up to the northeastern corner of the Kerguelen Plateau before making its southward retroflection. It is shown that the major surface/subsurface waters found within the deep basin east of the Kerguelen Islands originate from the shelf around the Heard Island, rather than from the shallow shelf north of the Kerguelen Islands. |
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Programme |
688,1061 |
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Bachelor's thesis |
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ISSN |
2169-9291 |
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yes |
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Call Number |
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Serial |
5628 |
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Author |
Goutte A, Chevreuil M, Alliot F, Chastel O, Cherel Y, Eléaume M, Massé G, |
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Title |
Persistent organic pollutants in benthic and pelagic organisms off Adélie Land, Antarctica
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Type |
Journal Article |
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Year |
2013 |
Publication |
Marine Pollution Bulletin |
Abbreviated Journal |
Mar. Pollut. Bull. |
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Volume |
77 |
Issue |
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Pages |
82-89 |
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Keywords |
Polar ecosystem, Persistent organic pollutants, Echinoderm, Fish, Krill, Seabird, |
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Abstract |
Abstract |
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Programme |
109 |
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ISSN |
0025-326X |
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yes |
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Call Number |
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Serial |
4750 |
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Author |
De Lauretis, M.; Francia, P.; Vellante, M.; Piancatelli, A.; Villante, U.; Di Memmo, D. |
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Title |
ULF geomagnetic pulsations in the southern polar cap: Simultaneous measurements near the cusp and the geomagnetic pole |
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 |
Issue |
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Pages |
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Keywords |
polar cap phenomena; cusp; MHD waves and turbulence; solar wind/magnetosphere interactions; 2776 Magnetospheric Physics: Polar cap phenomena; 2706 Magnetospheric Physics: Cusp; 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions; 2752 Magnetospheric Physics: MHD waves and instabilities; 2740 Magnetospheric Physics: Magnetospheric configuration and dynamics |
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Abstract |
During November 2003, a 1-week test campaign of ULF geomagnetic field measurements was conducted at the new Italian/French base of Concordia (Dome C, Antarctic plateau), close to the geomagnetic pole, at a corrected geomagnetic latitude of ?89°S. An analysis of these measurements is presented, together with a comparison with simultaneous measurements conducted at the Italian “Mario Zucchelli” base, at Terra Nova Bay, also located in the polar cap, but at lower latitude (?80°S). The variable solar wind and interplanetary magnetic field conditions made it possible to monitor the Pc 3–4 ULF pulsation activity under different magnetospheric conditions. For quiet conditions, the pulsation power does not show evidence for a diurnal modulation at Dome C, while at Terra Nova Bay it maximizes around local magnetic noon. This result can be interpreted in terms of the different latitude of the two stations which might be linked to different magnetospheric regions: Dome C deep in the polar cap, and Terra Nova Bay approaching the cusp around noon. Conversely, during a strong geomagnetic storm, the wave activity at the two stations becomes very similar, and major ground manifestations are driven by strong solar wind pressure pulses. The clear dependence of the pulsation frequency with the interplanetary magnetic field strength suggests that upstream waves can be the source of pulsations not only at Terra Nova Bay but also at Dome C, in the deep polar cap. We also find a clear relationship between the pulsation power and the solar wind speed which is more pronounced at Dome C, where cusp-related phenomena are not present. |
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Programme |
1130 |
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Publisher |
American Geophysical Union |
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Edition |
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ISSN |
0148-0227 |
ISBN |
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Approved |
yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5494 |
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| Permanent link to this record |
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Author |
Francia, P.; Lanzerotti, L.J.; Villante, U.; Lepidi, S.; Di Memmo, D. |
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Title |
A statistical analysis of low-frequency magnetic pulsations at cusp and cap latitudes in Antarctica |
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 |
Issue |
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Pages |
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Keywords |
polar cap and cusp pulsations; magnetospheric wave guide modes; field line resonances; open/closed field line boundary; 2784 Magnetospheric Physics: Solar wind/magnetosphere interactions; 2740 Magnetospheric Physics: Magnetospheric configuration and dynamics; 2776 Magnetospheric Physics: Polar cap phenomena; 2706 Magnetospheric Physics: Cusp; 2752 Magnetospheric Physics: MHD waves and instabilities |
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Abstract |
We report a statistical analysis of low-frequency magnetic variations (magnetic pulsations, 0.8–7 mHz) at South Pole (74°S corrected geomagnetic latitude) and Terra Nova Bay (80°S) during 1996. The results show that at South Pole (at cusp latitudes) the pulsation power exhibits two maxima during the day, one in the local premidnight and the other in the morning. The first maximum disappears when the analysis is restricted to northward interplanetary magnetic field conditions (B z > 1 nT), suggesting that it might be associated to substorm phenomena. During closed magnetospheric conditions, when the cusp is expected to be located poleward with respect to the station, the spectral and polarization characteristics of pulsations between 1 and 3 mHz suggest that resonant oscillations of the outermost closed field lines commonly occur at South Pole in the local morning. At Terra Nova Bay, in the polar cap, the pulsation power is much lower and its diurnal variation is characterized by a single maximum, which occurs around local noon, when the station approaches the cusp. The corresponding polarization pattern indicates that Terra Nova Bay is always located poleward with respect to resonant field lines. |
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Programme |
1130 |
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Publisher |
American Geophysical Union |
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ISSN |
0148-0227 |
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yes |
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Call Number |
IPEV @ Thierry.Lemaire @ |
Serial |
5495 |
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Author |
Koubbi Philippe, O'Brien Colleen, Loots Christophe, Giraldo Carolina, Smith Martina, Tavernier Eric, Vacchi Marino, Vallet Carole, Chevallier Jean, Moteki Masato, |
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Title |
Spatial distribution and inter-annual variations in the size frequency distribution and abundances of Pleuragramma antarcticum larvae in the Dumont dUrville Sea from 2004 to 2010
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Type |
Journal Article |
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Year |
2011 |
Publication |
Polar Science |
Abbreviated Journal |
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Volume |
5 |
Issue |
2 |
Pages |
225-238 |
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Keywords |
Pleuragramma antarcticum, East Antarctic shelf, Fish larvae, Life cycle, Inter-annual variations, |
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Abstract |
This paper investigates the abundance and distribution of Pleuragramma antarcticum larvae by size class in the Dumont dUrville Sea from 2004 to 2010. Samples were collected between Dumont dUrville station and the Mertz Glacier Tongue onboard the RV lAstrolabe for studying the inter-annual and spatial distribution of fish larvae and the TRV Umitaka Maru for looking at life stages vertical distributions. The seabed depression adjacent to the Mertz Glacier Tongue and in Commonwealth Bay hosted high abundances of small P. antarcticum larvae, while larger larvae were found in lower abundance and further offshore. We found that canyons, sea ice, stability of the water column and temperatures are important features for determining suitable areas for young larvae. |
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Programme |
1142 |
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Bachelor's thesis |
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ISSN |
1873-9652 |
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yes |
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Call Number |
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Serial |
3301 |
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Author |
Mayzaud P, Chevallier J, Tavernier E, Moteki M, Koubbi P, |
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Title |
Lipid composition of the Antarctic fish Pleuragramma antarcticum. Influence of age class
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Type |
Journal Article |
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Year |
2011 |
Publication |
Polar Science |
Abbreviated Journal |
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Volume |
5 |
Issue |
2 |
Pages |
264-271 |
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Keywords |
Pleuragramma antarcticum, Age class, Lipid composition, Fatty acid trophic markers, |
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Abstract |
Larvae and juvenile stages of Pleuragramma antarcticum have been collected in the Dumont DUrville Sea (East Antarctica) during summer 2008 on board the TRV Umitaka Maru during the CEAMARC survey. Detailed analyses of their lipid class and fatty acid compositions were carried out. P. antarcticum showed a pronounced ontogenic lipid accumulation with increasing size. Larvae displayed a dominance of polar lipids (83% of total lipids) and low percentage of triglycerides (7%). Conversely juveniles showed an increasing accumulation of triglycerides (up to 72.4%). The fatty acid composition of polar lipids remained rather stable between stages with 22:6n3 and 20:5n3 as dominant contributors. The relatively minor ontogenic changes, e.g. increase of monounsaturated and decrease of C18 polyunsaturated fatty acids, may reflect the influence of differences in diet. Triglycerides showed that all three age classes are well segregated in term of fatty acid composition. Larvae triglycerides are characterized by significant percentages of 16:0, 20:5n3, 20:6n3 and to a minor extent 18:4n3, which suggest a prymnesiophyte based diet. Juveniles are characterized by larger percentages of C20:1 and C22:1 acids, considered as markers of Calanus type copepods. The increasing contribution of 18:1n9 in the triglycerides of the older juveniles suggests a gradual and increasing shift from a copepod dominant diet to an euphausiid dominant diet. Fatty acid trophic markers pattern suggests a shift from a phytophagous and omnivorous diet for larvae to a carnivorous diet for juveniles. |
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1142 |
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1873-9652 |
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yes |
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Call Number |
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Serial |
3332 |
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Author |
Javier Franco, Jerome Fort, Isabel García-Barón, Pauline Loubat, Maite Louzao, Oihane del Puerto, Izaskun Zorita |
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Title |
Incidence of plastic ingestion in seabirds from the Bay of Biscay (southwestern Europe) |
Type |
Journal |
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Year |
2019 |
Publication |
Marine pollution bulletin |
Abbreviated Journal |
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Volume |
146 |
Issue |
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Pages |
387-392 |
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Keywords |
Plastic pollution; Plastic ingestion; Seabirds; Bay of Biscay; Marine Strategy Framework Directive |
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Abstract |
Seabirds have been widely used to monitor marine debris by the analysis of plastic ingestion. With the aim of obtaining the first data on ingestion of plastics by different seabird species in the Bay of Biscay and evaluating their suitability as biomonitors of plastic pollution in this area, a total of 159 seabirds of fifteen species were analyzed. Plastics were found in 26 birds (16% of the individuals) of nine species (60% of the species). Frequency of occurrence of plastics varied between 0% (Razorbill) and 100% (species of the family Procellariidae). Considering several criteria to assess their suitability as biomonitors of plastic pollution (frequency of occurrence of plastic ingestion, species abundances and stranding occurrence in the Bay of Biscay), the Common Guillemot and the Atlantic Puffin seem the most promising candidates. This study provides the first data on plastic ingestion in seabirds of the Bay of Biscay. |
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Programme |
388 |
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Bachelor's thesis |
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0025-326X |
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yes |
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Call Number |
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Serial |
7486 |
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| Permanent link to this record |
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Author |
Miyashita, Y.; Ieda, A.; Kamide, Y.; Machida, S.; Mukai, T.; Saito, Y.; Liou, K.; Meng, C.-I.; Parks, G.K.; McEntire, R.W.; Nishitani, N.; Lester, M.; Sofko, G.J.; Villain, J.-P. |
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Title |
Plasmoids observed in the near-Earth magnetotail at X ? ?7 RE |
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 |
Issue |
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Pages |
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Keywords |
plasmoid; Geotail; 2723 Magnetospheric Physics: Magnetic reconnection; 2744 Magnetospheric Physics: Magnetotail; 2790 Magnetospheric Physics: Substorms; 2704 Magnetospheric Physics: Auroral phenomena; 2736 Magnetospheric Physics: Magnetosphere/ionosphere interactions |
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Abstract |
Recent studies have statistically shown that the magnetic reconnection site at substorm expansion onset is located in the magnetotail at X ? ?20 R E on average. For a substorm event that occurred at ?0153 UT on 2 July 1996, however, Geotail observed a series of tailward but slow flows with southward magnetic fields fairly close to the Earth at (X, Y) ? (?7, 9) R E
. The flows had enhancements of the total pressure and the total magnetic field as well as bidirectional field-aligned low-energy electrons in their central part. We interpret these as signatures for tailward moving small plasmoids with scales of ?0.5–3 R E
. Considering that GOES-8 observed a dipolarization at (X, Y) ? (?4, 5) R E after the expansion onset, we estimate that the magnetic reconnection occurred between the Geotail and GOES-8 positions. UVI auroral images from Polar and ground magnetic field data show that this substorm, initiated at ?20 hours MLT and ?64° magnetic latitude, was not very intense, and the period examined was not during an intense storm. The southward interplanetary magnetic field (IMF) was not very large, while the large duskward IMF persisted for more than 12 hours before the onset as well as the somewhat large solar wind dynamic pressure. It seems likely that the global ionospheric convection was not very strong. Locally enhanced convection and auroral oval expansion due to the large IMF B y and the solar wind dynamic pressure might lead to the initiation of the magnetic reconnection much closer to the Earth than usual. |
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312;911 |
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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 @ |
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5619 |
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