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Wöppelmann G., L. Testut et R. Créach. (2011). La montée du niveau des océans par marégraphie et géodésie spatiale : contributions françaises à une problématique mondiale. 0373-3629, 8(777), 14–1.
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Woppelmann G. (1997). Localisation par technique GPS des stations d'observation du niveau de la mer du réseau WOCE..
Abstract: Thèse de Doctorat de l'Observatoire de Paris
Programme: 688
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Wookey James. (2012). Direct probabilistic inversion of shear wave data for seismic anisotropy
. Geophysical Journal International , 189 (2 ), 1025–1037 .
Abstract: Shear wave splitting is perhaps the most unambiguous signature of the effect of anisotropic materials on the propagation of seismic waves. It has been used extensively to study anisotropy in the Earth, at global scales from the inner core to the tectonics of the uppermost mantle and crust, and at smaller scales for imaging deformation in hydrocarbon reservoirs. Well-established techniques exist for measuring shear wave splitting in a single (three-component) seismogram and more recently these have been extended to treat shear wave splitting in a tomographic fashion: determining non-uniform anisotropic models using large data sets of splitting measurements. Here, I propose an extension to a recent shear wave splitting tomography methodology which incorporates the data analysis into the inversion itself. This methodology uses a non-linear neighbourhood algorithm inversion to explore the parameter space defined by an anisotropic model consisting of a number of uniform domains. Each candidate model is assessed by applying the splitting it predicts to the entire data set. This approach is computationally expensive, but is highly amenable to parallelization. I apply the methodology to three simple synthetic cases to demonstrate the utility of the method. Finally, I apply the approach to the problem of inferring two-layer anisotropy from SKS splitting, which is a commonly attempted problem in global seismology. This uses data from the seismic station EKTN, where two-layer splitting has been previously inferred. This highlights some of the inherent trade-offs with such studies, and emphasizes the need to incorporate extra information to resolve these. This method is applicable to shear wave anisotropy analysis in a broad range of settings from global to reservoir scale.
Programme: 133
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Wolff E.W., Hall J.S., Mulvaney R., Pasteur E.C., Wagenbach D. & Legrand M. (1998). Relationship between chemistry of air, fresh snow and firn cores for aerosol species in coastal Antarctica. J. Geophys. Res., 103, 11057–11070.
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Wolff E.W. & Cachier H. (1998). Concentrations and seasonal cycle of black carbon in aerosol at a coastal Antarctic station. J. Geophys. Res., 103, 11033–11041.
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Wolff E.R., Legrand M.R. & Wagenbach D. (1998). Coastal Antarctic aerosol and snowfall chemistry. J. Geophys. Res., 103, 10927–10934.
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Wolff E., Basile I., Petit J.R. & Schwander J. (1999). Comparison of Holocene electrical records from Dome C and Vostok, Antarctica. Annals of glaciology, 29, 89–93.
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Wojczulanis-Jakubas Katarzyna, Kilikowska Adrianna, Fort Jérôme, Gavrilo Maria, Jakubas Dariusz, Friesen Vicki, . (2015). No evidence of divergence at neutral genetic markers between the two morphologically different subspecies of the most numerous Arctic seabird
. Ibis (Lond. 1859), 157(4), 787–797.
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Woehler E.J., Cooper J., Croxall J.P., Fraser W.R., Kooyman G.L., Miller G.D., Nel D.C., Patterson D.L., Peter H.U., Ribic C.A., Salwicka K., Trivelpiece W.Z. & Weimerskirch H. (2001). A statistical assessment of the status and trends of Antarctic and Subantarctic seabirds..
Abstract: Report on SCAR BBS Workshop on Southern Ocean seabird populations
43pages
Programme: 109
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Wittlinger Gérard, Farra Véronique, . (2015). Evidence of unfrozen liquids and seismic anisotropy at the base of the polar ice sheets
. Polar Science, 9(1), 66–79.
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.
Keywords: Polar ice, Seismic anisotropy, Unfrozen liquids,
Programme: 133
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