|
|
Yiou P., Fuhrer K., Meeker L.D., Jouzel J., Johnsen S.J. & Mayewski P.A. (1997). Paleoclimatic variability inferred from the spectral anlysis of Greenland and Antarctic ice core data. J. Geophys. Res., 102(c12), 26441–26454.
|
|
|
|
Yiou F., Raisbeck G.M., Baumgartner S., Beer J., Hammer C., Johnsen S., Jouzel J., Kubik P.W., Lestringuez J., Stievenard M., Suter & Yiou P. (1997). 10Be in the greenland Ice Core Project ice core at Summit Greenland. J. Geophys. Res., 102(c12), 26783–26794.
|
|
|
|
Yanzhi Cao, Zhuang Jiang, Becky Alexander, Jihong Cole-Dai, Joel Savarino, Joseph Erbland, Lei Geng. (2022). On the potential fingerprint of the Antarctic ozone hole in ice-core nitrate isotopes: a case study based on a South Pole ice core (Vol. 22).
Abstract: Column ozone variability has important implications for surface photochemistry and the climate. Ice-core nitrate isotopes are suspected to be influenced by column ozone variability and δ15N(NO) has been sought to serve as a proxy of column ozone variability. In this study, we examined the ability of ice-core nitrate isotopes to reflect column ozone variability by measuring δ15N(NO) and Δ17O(NO) in a shallow ice core drilled at the South Pole. The ice core covers the period 1944–2005, and during this period δ15N(NO) showed large annual variability ((59.2 ± 29.3) ‰ ), but with no apparent response to the Antarctic ozone hole. Utilizing a snow photochemical model, we estimated 6.9 ‰ additional enrichments in δ15N(NO) could be caused by the development of the ozone hole. Nevertheless, this enrichment is small and masked by the effects of the snow accumulation rate at the South Pole over the same period of the ozone hole. The Δ17O(NO) record has displayed a decreasing trend by ∼ 3.4 ‰ since 1976. This magnitude of change cannot be caused by enhanced post-depositional processing related to the ozone hole. Instead, the Δ17O(NO) decrease was more likely due to the proposed decreases in the O3 HOx ratio in the extratropical Southern Hemisphere. Our results suggest ice-core δ15N(NO) is more sensitive to snow accumulation rate than to column ozone, but at sites with a relatively constant snow accumulation rate, information of column ozone variability embedded in δ15N(NO) should be retrievable.
Programme: 1177
|
|
|
|
Yano Tomoko, Tanimoto T, Rivera L, . (2009). The ZH ratio method for long-period seismic data: inversion for S-wave velocity structure
. 0956-540X, 179(1), 413–424.
Abstract: The particle motion of surface waves, in addition to phase and group velocities, can provide useful information for S-wave velocity structure in the crust and upper mantle. In this study, we applied a new method to retrieve velocity structure using the ZH ratio, the ratio between vertical and horizontal surface amplitudes of Rayleigh waves. Analysing data from the GEOSCOPE network, we measured the ZH ratios for frequencies between 0.004 and 0.05 Hz (period between 20 and 250 s) and inverted them for S-wave velocity structure beneath each station. Our analysis showed that the resolving power of the ZH ratio is limited and final solutions display dependence on starting models; in particular, the depth of the Moho in the starting model is important in order to get reliable results. Thus, initial models for the inversion need to be carefully constructed. We chose PREM and CRUST2.0 in this study as a starting model for all but one station (ECH). The eigenvalue analysis of the least-squares problem that arises for each step of the iterative process shows a few dominant eigenvalues which explains the cause of the inversion's initial-model dependence. However, the ZH ratio is unique in having high sensitivity to near-surface structure and thus provides complementary information to phase and group velocities. Application of this method to GEOSCOPE data suggest that low velocity zones may exist beneath some stations near hotspots. Our tests with different starting models show that the models with low-velocity anomalies fit better to the ZH ratio data. Such low velocity zones are seen near Hawaii (station KIP), Crozet Island (CRZF) and Djibuti (ATD) but not near Reunion Island (RER). It is also found near Echery (ECH) which is in a geothermal area. However, this method has a tendency to produce spurious low velocity zones and resolution of the low velocity zones requires further careful study. We also performed simultaneous inversions for volumetric perturbation and discontinuity-depth perturbation. While its formulation and inversion were straightforward, there seemed to be a difficult trade-off problem between volumetric perturbation and discontinuity-depth perturbation.
Keywords: Surface waves and free oscillations, Seismic tomography, Wave propagation,
Programme: 133
|
|
|
|
Yano H., Engrand C. & Maurette M. (1996). Hypervelocity impact experiments using Antarctic Micrometeorites. (Vol. XXI).
Abstract: 21 Symp. on Antarctic Meteorites, NIPR
Programme: 226
|
|
|
|
Yann Tremblay, Yves Cherel, Marc Oremus, Torkild Tveraa and Olivier Chastel. (2003). Unconventional ventral attachment of time-depth recorders as a new method for investigating time budget and diving behaviour of seabirds. J. Exp. Biol., 206, 1929–1940.
|
|
|
|
Yann Rolland, Matthias Bernet, Peter van der Beek, Cécile Gautheron, Guillaume Duclaux, Jérôme Bascou, Mélanie Balvay, Laura Héraudet, Christian Sue, René-Pierre Ménot. (2019). Late Paleozoic Ice Age glaciers shaped East Antarctica landscape (Vol. 506).
Abstract: The erosion history of Antarctica is fundamental to our understanding of interlinks between climate and glacier dynamics. However, because of the vast polar ice sheet covering more than 99% of Antarctica land mass, the continental surface response to glacial erosion remains largely unknown. Over the last decade the subglacial topography of Antarctica has been imaged by airborne radar surveys. These studies revealed high and complex sub-glacial relief in the core of the East Antarctic shield, interpreted as resulting from rifting episodes and low long-term erosion rates, or repeated large-scale glacial retreats and advances. In East Antarctica, thermochronology studies have revealed a spatially localized Cenozoic erosion starting after 34 Ma, with a maximum denudation of 2 km in the Lambert Trough. Low pre-glacial erosion rates before 34 Ma have been inferred since the Permian period, following a phase of significant (>2 km) erosion during the Late Paleozoic between 350 and 250 Ma. However, the exact extent, magnitude and significance of this Late-Paleozoic erosion phase remain elusive. Here we show that homogeneous exhumation occurred at the scale of the Terre Adélie margin of East Antarctica in response to major glacial erosion during the Late Paleozoic Ice Age (LPIA). Our data require homogeneous exhumation and >4 km erosion between 340 and 300 Ma, along a 600-km profile along the Terre Adélie–George V Land coast. The data are inconsistent with either exhumation during Permian rifting, or with significant (>1.5 km) Cenozoic glacial erosion, which requires LPIA glaciers to have been temperate, promoting glacial sliding, erosion and sediment transfer, even at high latitudes, unlike in the present situation.
Keywords: Antarctica erosion exhumation glaciation LPIA thermochronology
Programme: 1003
|
|
|
|
Yann Méheust, Karine Delord, Anne-Sophie Bonnet-Lebrun, Thierry Raclot, Julien Vasseur, Jimmy Allain, Virgil Decourteillle, Charles-André Bost, Christophe Barbraud. (2024). Human infrastructures correspond to higher Adélie penguin breeding success and growth rate (Vol. 204).
Abstract: Anthropogenic activities generate increasing disturbance in wildlife especially in extreme environments where species have to cope with rapid environmental changes. In Antarctica, while studies on human disturbance have mostly focused on stress response through physiological and behavioral changes, local variability in population dynamics has been addressed more scarcely. In addition, the mechanisms by which breeding communities are affected around research stations remain unclear. Our study aims at pointing out the fine-scale impact of human infrastructures on the spatial variability in Adélie penguin (Pygoscelis adeliae) colonies dynamics. Taking 24 years of population monitoring, we modeled colony breeding success and growth rate in response to both anthropic and land-based environmental variables. Building density around colonies was the second most important variable explaining spatial variability in breeding success after distance from skua nests, the main predators of penguins on land. Building density was positively associated with penguins breeding success. We discuss how buildings may protect penguins from avian predation and environmental conditions. The drivers of colony growth rate included topographical variables and the distance to human infrastructures. A strong correlation between 1-year lagged growth rate and colony breeding success was coherent with the use of public information by penguins to select their initial breeding site. Overall, our study brings new insights about the relative contribution and ecological implications of human presence on the local population dynamics of a sentinel species in Antarctica.
Keywords: Antarctica Breeding habitat quality Human disturbance Population dynamics Population monitoring Pygoscelis adeliae
Programme: 1091
|
|
|
|
Yann Borjon-Privé. (2013). Dolgan oral tradition in an Arctic continuum (Tungus, Yakuts, Russians): about the beginning and origins of ourselves..
Abstract: This communication took at the International Colloquium “Human-environment relations: skills, knowledge, emotions and politics in Siberia and China (Evenk and Even peoples)”, organised at the Observatory Versailles Saint-Quentin-en-Yvelines by the University of Versailles Saint-Quentin-en-Yvelines (UVSQ, org. Alexandra Lavrillier).
The aim of this communication was to highlight the importance of several old sources concerning the past of the Dolgan society. Their data provide detailed knowledge of the Dolgan history and show relations with Tungusic, Yakutic and Russian groups. They enable also to study and explain the representations of the Dolgan regarding the past of their own society.
Publications are in progress.
Programme: 1121
|
|
|
|
Yann Borjon-Privé. (2014). Note sur les épopées dolganes (Arctique sibérien) / Note on the Dolgan epics (Siberian Arctic). Études Mongoles et Sibériennes, Centrasiatiques et Tibétaines, 45(June 30th. 2014).
Abstract: The Dolgans form a society who lives in the Siberian Arctic, in the northern peninsula of the Eurasian continent. Since the beginning of XXth century, researchers have gathered epics by then, sung or told. From published texts, it becomes possible to observe some structural rules. Some poetical formulations come too or differ. Thus narratives changes show the richness and the subtlety of the epic. The hero follows new path too, and then he tests social or religious rules. The main objective of this note is to define a corpus of study, from which further analyses will be carried out in connection with historical context and Dolgan religious system.
The article is related to a communication. It took place in a day of study in Paris on November 28th 2014 (EPHE-CEMS Paris, RARE-Grenoble III, orgs. Florence Goyet, Jean-Luc Lambert).
Programme: 1121
|
|
