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Schimmel M, Stutzmann E, Gallart J, . (2011). Using instantaneous phase coherence for signal extraction from ambient noise data at a local to a global scale
. Geophysical Journal International, 184(1), 494–506.
Abstract: Stacks of ambient noise cross-correlations are more and more routinely used to extract empirical Green's functions between station pairs. The success of the cross-correlations is due to waves which are recorded by both stations and that constructively sum at lag times which equal their propagation time between the station pair. Stacking cross-correlograms corresponding to different time spans improves the azimuthal noise coverage and further enhances the signals. Here we show how the instantaneous phase coherence can be used for a more efficient signal extraction from ambient noise cross-correlations. The instantaneous phase coherence is obtained by analytic signal processing and can be employed through the phase cross-correlation and/or through the time-frequency domain phase-weighted stack. The phase cross-correlation is more sensitive to waveform similarity but less sensitive to strong amplitude features than the conventional cross-correlation. The time-frequency domain phase-weighted stack cleans the ambient noise cross-correlograms by attenuating incoherent noise and permits an improved signal identification. We show that both approaches are powerful tools in the recovery of signals from ambient noise data and show examples where they improve the extraction of P and Rayleigh waves by considering local and global scale applications.
Keywords: Time series analysis, Interferometry, Body waves, Surface waves and free oscillations,
Programme: 133
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Di Giacomo Domenico, Parolai Stefano, Bormann Peter, Grosser Helmut, Saul Joachim, Wang Rongjiang, Zschau Jochen, . (2010). Suitability of rapid energy magnitude determinations for emergency response purposes
. 0956-540X, 180(1), 361–374.
Keywords: Time series analysis, Earthquake source observations, Body-waves,
Programme: 133
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. (2014). Behav. Ecol. Sociobiol. , 68(5), 721–732-.
Abstract: Glucocorticoid hormones (GCs) are important mediators of physiological and behavioral responses to stress. While many studies have evaluated the environmental, behavioral, or physiological correlates of GCs and their effects on reproductive performances, further work is needed to clarify the relationship between GCs and fitness. Assessing the effects of increased GC levels on specific behaviors of breeding animals should improve our understanding of how GCs affect parental care. In this experimental study, we measured the effects of an experimental increase in corticosterone (CORT, the main avian GC) levels on the behavior of free-living male Ad,lie penguins (Pygoscelis adeliae) within the colony, their reproductive output, and the indirect consequences of both on the behavior of their partners. We show that increased CORT levels in males decreased their foraging time at sea while increased their attendance at the nest, although their attentiveness toward the nest itself decreased. In addition, treated males spent more time on comfort behaviors (e.g., preening), vocalizing, and engaging in positive social interactions relative to controls. Treatment further affected the behavior of their partners, but not chick begging and feeding rates. Penguins with increased CORT levels also exhibited decreased reproductive output. Previous studies of Ad,lie penguins in different life history stages and environmental conditions suggest that the consequences of CORT treatment on reproductive performance are context-dependent. In addition to the potential delay in the effects of increased CORT levels on reproduction, this context dependence should be taken into account when studying the behavior of free-living animals in relation to stress-inducing situations.
Keywords: Time budget, Behavior, Glucocorticoid, Pygoscelis adeliae, Reproduction, Reproductive performances,
Programme: 1091
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Sun Xinlei, Song Xiaodong, . (2008). Tomographic inversion for three-dimensional anisotropy of Earths inner core
. Physics of the Earth and Planetary Interiors, 167(12), 53–70.
Keywords: Three-dimensional inner core anisotropy, Inner inner core, Three-dimensional ray tracing,
Programme: 133
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. (2005). Dynamics in the polar thermosphere after the coronal mass ejection of 28 October 2003 observed with the EPIS interferometer at Svalbard. J. Geophys. Res., 110.
Abstract: The upper atmosphere dynamics in the polar cap is mainly driven by ion-drag momentum sources imposed by the mapping of magnetosphere convection into the thermosphere/ionosphere and by Joule and auroral particle heating. Auroral particles also enhance conductivity particularly in the middle and lower ionosphere. Changes in the magnetospheric energy and momentum sources can significantly modify the wind circulation during geomagnetic storms. To observe these effects, a Michelson interferometer has been installed in Svalbard to measure winds in the thermosphere. Prior to 30 October 2003, cloud cover over Svalbard rendered the conditions unfavorable for optical observation. However, meteorological conditions improved after this date to enable the thermospheric response to the 28 October coronal mass ejection to be made. During quiet geomagnetic conditions measured wind velocities were in good agreement with those predicted by the Horizontal Wind Model (HWM). During disturbed geomagnetic conditions, HWM tended to underestimate the observed velocities. Comparison of the wind observations with a physical model tended to show reasonable agreement during both the strongly driven and recovery phase of the storm. Although the physical model did not always capture the timing of the rapid changes in the wind response in the early phase of the storm, the amplitudes of the fluctuations were in good agreement. After the initial phase the physical model agreed well with both the timing and amplitude of the meridional and zonal wind fluctuations. The meridional wind component was also derived from the EISCAT Svalbard Radar ion velocity and was found to be in close agreement with the optical winds observations.
Keywords: thermosphere; CME; neutral winds; EPIS; ESR; 0310 Atmospheric Composition and Structure: Airglow and aurora; 0358 Atmospheric Composition and Structure: Thermosphere: energy deposition; 7513 Solar Physics, Astrophysics, and Astronomy: Coronal mass ejections
Programme: 384
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Hill-Falkenthal, J., A. Priyadarshi, J. Savarino, and M. H. Thiemens. (2013). Seasonal variations in 35S and Δ17O of sulfate aerosols on the Antarctic plateau. J. Geophys. Res. Atmos., .
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Delille D., Coulon F. & Pelletier E. (2004). Effects of temperature warming during a bioremediation study of natural and nutrient amended hydrocarbon contaminated sub-Antarctic soils. Cold regions science and technology, 40, 61–70.
Keywords: Temperature ; Soil petroleum hydrocarbon ; Bioremediation ; Antarctica
Programme: 193
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. (2008). Ectosymbiosis is a critical factor in the local benthic biodiversity of the Antarctic deep sea
. Mar. Ecol. Prog. Ser., 364, 67–76.
Abstract: In deep-sea benthic environments, competition for hard substrates is a critical factor in the distribution and diversity of organisms. In this context, the occurrence of biotic substrates in addition to mineral substrates may change the characteristics of sessile fauna. We tested this hypothesis at different localities of the Weddell Sea (Antarctica) by studying the diversity of ectosymbionts living on the spines of cidaroids (echinoids). The presence of cidaroids promoted a higher total specific richness and increased sessile species abundance, but did not change the diversity. Analyses of species distribution suggested that the cidaroids are a favourable habitat for sessile organisms, compared to rocks, but are colonized by relatively specialist sessile species, leaving the unfavourable rock habitat to more generalist species. Therefore, our study highlights the role of some living organisms, such as cidaroids, as key species increasing Antarctic benthic deep-sea species richness through the niche they provide to symbiotic species.
Programme: 1124
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Qin Yilong, Capdeville Yann, Maupin Valerie, Montagner Jean-Paul, Lebedev Sergei, Beucler Eric, . (2008). SPICE benchmark for global tomographic methods
. Geophysical Journal International, 175(2), 598–616.
Abstract: The existing global tomographic methods result in different models due to different parametrization, scale resolution and theoretical approach. To test how current imaging techniques are limited by approximations in theory and by the inadequacy of data quality and coverage, it is necessary to perform a global-scale benchmark to understand the resolving properties of each specific imaging algorithm. In the framework of the Seismic wave Propagation and Imaging in Complex media: a European network (SPICE) project, it was decided to perform a benchmark experiment of global inversion algorithms. First, a preliminary benchmark with a simple isotropic model is carried out to check the feasibility in terms of acquisition geometry and numerical accuracy. Then, to fully validate tomographic schemes with a challenging synthetic data set, we constructed one complex anisotropic global model, which is characterized by 21 elastic constants and includes 3-D heterogeneities in velocity, anisotropy (radial and azimuthal anisotropy), attenuation, density, as well as surface topography and bathymetry. The intermediate-period (>32 s), high fidelity anisotropic modelling was performed by using state-of-the-art anisotropic anelastic modelling code, that is, coupled spectral element method (CSEM), on modern massively parallel computing resources. The benchmark data set consists of 29 events and three-component seismograms are recorded by 256 stations. Because of the limitation of the available computing power, synthetic seismograms have a minimum period of 32 s and a length of 10 500 s. The inversion of the benchmark data set demonstrates several well-known problems of classical surface wave tomography, such as the importance of crustal correction to recover the shallow structures, the loss of resolution with depth, the smearing effect, both horizontal and vertical, the inaccuracy of amplitude of isotropic S-wave velocity variation, the difficulty of retrieving the magnitude of azimuthal anisotropy and so on. The synthetic data set can be used to validate and calibrate new processing methodologies and has been made available to the scientific community at the Institut de Physique du Globe de Paris (IPGP) website (). Any group wishing to test their tomographic algorithm is encouraged to download the synthetic data.
Keywords: Surface waves and oscillations, Seismic anisotropy, Seismic tomography, Computational seismology,
Programme: 133
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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.
Keywords: Surface waves and free oscillations, Seismic tomography, Wave propagation,
Programme: 133
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