| Records |
| Author |
Peter S. Ungar, Blaire Van Valkenburgh, Alexandria S. Peterson, Aleksandr A. Sokolov, Natalia A. Sokolova, Dorothee Ehrich, Ivan A. Fufachev, Olivier Gilg, Alexandra Terekhina, Alexander Volkovitskiy, Viktor Shtro |
| Title |
Dental evidence for variation in diet over time and space in the Arctic fox, Vulpes lagopus |
Type |
Journal |
| Year |
2021 |
Publication |
Polar Biology |
Abbreviated Journal |
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| Volume |
44 |
Issue |
3 |
Pages |
509-523 |
| Keywords |
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| Abstract |
Studies of the effects of variation in resource availability are important for understanding the ecology of high-latitude mammals. This paper examines the potential of dental evidence (tooth wear and breakage) as a proxy for diet and food choice in Vulpes lagopus, the Arctic fox. It presents a preliminary study of dental microwear, gross wear score, and tooth breakage in a sample (n = 78 individuals) from the Yamal Peninsula of the Russian Arctic. While these measures have each been associated with feeding ecology in larger carnivorans (e.g., proportion of bone in the diet), they have yet to be combined in any study and have rarely been applied to smaller species or those from high latitudes. Arctic foxes from the north and south of the peninsula, and those from rodent peak and trough density periods, are compared to assess impact of changes in food availability across space and time. Results indicate that microwear textures vary in dispersion, with more variation in texture complexity, including higher values (suggesting more consumption of bone), in the rodent-poor period in the north of Yamal. Gross wear scores and tooth breakage are also significantly higher for the north of Yamal than the south. These data together suggest that dental evidence can provide important insights into variation in the feeding ecology of Arctic foxes and potentially into the impacts of changes in food abundance across space and time. |
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1036 |
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Edition |
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| ISSN |
1432-2056 |
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Approved |
yes |
| Call Number |
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Serial |
7982 |
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| Author |
Jana Maresova, Alena Suchackova Bartonova, Martin Konvicka, Toke T. Høye, Olivier Gilg, Jean-Claude Kresse, Nazar A. Shapoval, Roman V. Yakovlev, Zdenek Faltynek Fric |
| Title |
The story of endurance: Biogeography and the evolutionary history of four Holarctic butterflies with different habitat requirements |
Type |
Journal |
| Year |
2021 |
Publication |
Journal of Biogeography |
Abbreviated Journal |
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| Volume |
48 |
Issue |
3 |
Pages |
590-602 |
| Keywords |
COI Ef-1α insect Lepidoptera mammoth steppe Pleistocene Quaternary RpS5 species distribution modelling |
| Abstract |
Aim Biogeographical studies on the entire ranges of widely distributed species can change our perception of species’ range dynamics. We studied the effects of Pleistocene glacial cycles on current butterfly species distributions, aiming to uncover complex biogeographic patterns in the Holarctic, a region dramatically affected by Cenozoic climate change. Location Eurasia and North America. Taxon Boloria chariclea, Agriades optilete, Carterocephalus palaemon, Oeneis jutta. Methods We reconstructed the biogeographic history of four butterfly species differing in habitat preferences (B. chariclea – tundra, A. optilete – bogs, C. palaemon – temperate grasslands, O. jutta – taiga), using one mitochondrial and two nuclear DNA markers and species distribution modelling. Results Except for B. chariclea, all species originated in Eurasia. The open habitat species A. optilete and C. palaemon formed widely distributed east-west genetic clusters in continental Asia and clusters separated from them in Europe. Genetic clusters of the taiga species O. jutta were not geographically separated in Eurasia, suggesting Pleistocene fragmentation and recent reconnection. The glaciated North America was recolonized from Beringian and southerly situated refugia by all four species. Main conclusions The Pleistocene mammoth steppe allowed a widespread continuous distribution of open habitat butterflies, while in contrast the distribution of a taiga-specialist species was more limited. In the mostly flat and continental North Asia, the butterflies of various types of open habitats survived ice age in widely distributed east-west belts. In the mountainous and oceanic regions of Europe, Beringia and west North America, all four species persisted in contracted areas during the glacials. After deglaciation, they expanded their ranges and formed contact zones among populations. To conclude, the harsh climate of the glacials did not represent an obstacle for butterflies. Instead, different habitat specialists selected their own ways to thrive in the dynamic conditions of Quaternary glacial periods. |
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1036 |
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Edition |
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| ISSN |
1365-2699 |
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yes |
| Call Number |
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Serial |
7984 |
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| Author |
Rune Dietz, Jérôme Fort, Christian Sonne, Céline Albert, Jan Ove Bustnes, Thomas Kjær Christensen, Tomasz Maciej Ciesielski, Jóhannis Danielsen, Sam Dastnai, Marcel Eens, Kjell Einar Erikstad, Anders Galatius, Svend-Erik Garbus, Olivier Gilg, Sveinn Are Hanssen, Björn Helander, Morten Helberg, Veerle L. B. Jaspers, Bjørn Munro Jenssen, Jón Einar Jónsson, Kaarina Kauhala, Yann Kolbeinsson, Line Anker Kyhn, Aili Lage Labansen, Martin Mørk Larsen, Ulf Lindstøm, Tone K. Reiertsen, Frank F. Rigét, Anna Roos, Jakob Strand, Hallvard Strøm, Signe Sveegaard, Jens Søndergaard, Jiachen Sun, Jonas Teilmann, Ole Roland Therkildsen, Thorkell Lindberg Thórarinsson, Rune Skjold Tjørnløv, Simon Wilson, Igor Eulaers |
| Title |
A risk assessment of the effects of mercury on Baltic Sea, Greater North Sea and North Atlantic wildlife, fish and bivalves |
Type |
Journal |
| Year |
2021 |
Publication |
Environment international |
Abbreviated Journal |
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| Volume |
146 |
Issue |
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Pages |
106178 |
| Keywords |
Biological effect Bird of prey Hg Marine mammal Risk threshold Seabird |
| Abstract |
A wide range of species, including marine mammals, seabirds, birds of prey, fish and bivalves, were investigated for potential population health risks resulting from contemporary (post 2000) mercury (Hg) exposure, using novel risk thresholds based on literature and de novo contamination data. The main geographic focus is on the Baltic Sea, while data from the same species in adjacent waters, such as the Greater North Sea and North Atlantic, were included for comparative purposes. For marine mammals, 23% of the groups, each composing individuals of a specific sex and maturity from the same species in a specific study region, showed Hg-concentrations within the High Risk Category (HRC) and Severe Risk Category (SRC). The corresponding percentages for seabirds, fish and bivalves were 2.7%, 25% and 8.0%, respectively, although fish and bivalves were not represented in the SRC. Juveniles from all species showed to be at no or low risk. In comparison to the same species in the adjacent waters, i.e. the Greater North Sea and the North Atlantic, the estimated risk for Baltic populations is not considerably higher. These findings suggest that over the past few decades the Baltic Sea has improved considerably with respect to presenting Hg exposure to its local species, while it does still carry a legacy of elevated Hg levels resulting from high neighbouring industrial and agricultural activity and slow water turnover regime. |
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1036 |
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| ISSN |
0160-4120 |
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Approved |
yes |
| Call Number |
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Serial |
7985 |
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| Author |
Afsaneh Mohammadzaheri, Karin Sigloch, Kasra Hosseini, Mitchell G. Mihalynuk |
| Title |
Subducted Lithosphere Under South America From Multifrequency P Wave Tomography |
Type |
Journal |
| Year |
2021 |
Publication |
Journal of Geophysical Research: Solid Earth |
Abbreviated Journal |
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| Volume |
126 |
Issue |
6 |
Pages |
e2020JB020704 |
| Keywords |
Andes intra-arc intra-oceanic subduction seismic tomography South America structure of the mantel |
| Abstract |
We analyze mantle structure under South America in the DETOX-P1 seismic tomography model, a global-scale, multifrequency inversion of teleseismic P waves. DETOX-P1 inverts the most extensive data set of broadband, waveform-based traveltime measurements to date, complemented by analyst-picked traveltimes from the ISC-EHB catalog. The mantle under South America is sampled by ∼665,000 cross-correlation traveltimes measured on 529 South American broadband stations and on 5,389 stations elsewhere. By their locations, depths, and geometries, we distinguish four high-velocity provinces under South America, interpreted as subducted lithosphere (“slabs”). The deepest (∼1,800–1,200 km depth) and shallowest (<600 km) slab provinces are observed beneath the Andean Cordillera near the continent’s northwest coast. At intermediate depths (1,200–900 km, 900–600 km), two slab provinces are observed farther east, under Brazil, Bolivia and Venezuela, with links to the Caribbean. We interpret the slabs relative to South America’s paleo-position over time, exploring the hypothesis that slabs sank essentially vertically after widening by viscous deformation in the mantle transition zone. The shallowest slab province carries the geometric imprint of the continental margin and represents ocean-beneath-continent subduction during Cenozoic times. The deepest, farthest west slab complex formed under intra-oceanic trenches during late Jurassic and Cretaceous times, far west of South America’s paleo-position adjoined to Africa. The two intermediate slab complexes record the Cretaceous transition from westward intra-oceanic subduction to eastward subduction beneath South America. This geophysical inference matches geologic records of the transition from Jura-Cretaceous, extensional “intra-arc” basins to basin inversion and onset of the modern Andean arc ∼85 Ma. |
| Programme |
133 |
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Series Title |
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Series Issue |
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Edition |
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| ISSN |
2169-9356 |
ISBN |
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Approved |
yes |
| Call Number |
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Serial |
7991 |
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| Author |
L A Ermert, K Sager, T Nissen-Meyer, A Fichtner |
| Title |
Multifrequency inversion of global ambient seismic sources |
Type |
Journal |
| Year |
2021 |
Publication |
Geophysical Journal International |
Abbreviated Journal |
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| Volume |
225 |
Issue |
3 |
Pages |
1616-1623 |
| Keywords |
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| Abstract |
We develop and apply a method to constrain the space- and frequency-dependent location of ambient noise sources. This is based on ambient noise cross-correlation inversion using numerical wavefield simulations, which honour 3-D crustal and mantle structure, ocean loading and finite-frequency effects. In the frequency range from 3 to 20 mHz, our results constrain the global source distribution of the Earth’s hum, averaged over the Southern Hemisphere winter season of 9 yr. During Southern Hemisphere winter, the dominant sources are largely confined to the Southern Hemisphere, the most prominent exception being the Izu-Bonin-Mariana arc, which is the most active source region between 12 and 20 mHz. Generally, strong hum sources seem to be associated with either coastlines or bathymetric highs. In contrast, deep ocean basins are devoid of hum sources. While being based on the relatively small number of STS-1 broad-band stations that have been recording continuously from 2004 to 2013, our results demonstrate the practical feasibility of a frequency-dependent noise source inversion that accounts for the complexities of 3-D wave propagation. It may thereby improve full-waveform ambient noise inversions and our understanding of the physics of noise generation. |
| Programme |
133 |
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Edition |
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| ISSN |
0956-540X |
ISBN |
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Medium |
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Expedition |
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| Notes |
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Approved |
yes |
| Call Number |
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Serial |
7992 |
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| Author |
Jun Xie, Risheng Chu, Sidao Ni |
| Title |
Evaluating Global Tomography Models With Antipodal Ambient Noise Cross-Correlation Functions |
Type |
Journal |
| Year |
2021 |
Publication |
Journal of Geophysical Research: Solid Earth |
Abbreviated Journal |
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| Volume |
126 |
Issue |
3 |
Pages |
e2020JB020444 |
| Keywords |
ambient noise cross-correlation functions antipodal surface waves mantle heterogeneity tomography model evaluation |
| Abstract |
It is essential to evaluate global tomography models, which provide important information for understanding Earth's structure and dynamics. Long-period surface waves propagating between antipodal stations are good candidates for this purpose since they depend on global-scale velocity variations in the upper mantle. In this study, we extract minor-arc and major-arc Rayleigh waves from ambient noise cross correlations between GEOSCOPE station AIS and ∼1,800 USArray stations near the antipode of AIS. We identify two Rayleigh-wave-focusing regions and simulate the observed maximum amplitude pattern at the antipodal region using synthetic surface waves based on three global tomography models. Our simulations suggest that seismic heterogeneity of the tomography models need to be inflated by a factor of 2–3 in oceanic regions to explain the observed focusing pattern of surface waves near the antipodal region. |
| Programme |
133 |
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Series Title |
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Series Issue |
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Edition |
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| ISSN |
2169-9356 |
ISBN |
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Medium |
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| Area |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
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Serial |
7993 |
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| Author |
R. Olmi, M. Bittelli, G. Picard, L. Arnaud, A. Mialon, S. Priori |
| Title |
Investigating the influence of the grain size and distribution on the macroscopic dielectric properties of Antarctic firn |
Type |
Journal |
| Year |
2021 |
Publication |
Cold Regions Science and Technology |
Abbreviated Journal |
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| Volume |
185 |
Issue |
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Pages |
103254 |
| Keywords |
Antarctica Close−off Dielectric measurements Dielectric model Firn Full wave EM simulations Ice cores |
| Abstract |
This study is based on the analysis of detailed measurements of firn dielectric properties performed in Antarctica through coring down to 106 m. Dielectric measurements in the frequency band (0.4–2.5 GHz) have been carried out using an open−resonator probe. Density was also measured for the same samples. The experimental results confirmed the well−known dependence of the real part of permittivity ε′ on depth and density, showing an increase of ε′ with density. The imaginary part also increases with depth with a rather complex dependence on frequency, probably due to the presence of salts or impurities. The analysis of the experimental data was performed by implementing 3D and 2D full wave numerical models, to simulate a mixture of firn crystals at prescribed densities, corresponding to the measured densities on the ice cores. The numerical analysis of the ensemble of inclusions showed that the usual symmetric formulae used for modeling ice dielectric properties agree with the average results of the simulation, but they are not able to explain the spreading of the measured data at given density. A dielectric model was then developed allowing for quantification of the dependence of dielectric properties on density, by combining two models: one consisting in firn crystals into an air host, the other assuming the presence of air inclusions into a homogeneous firn host. The weighted equation is based on the volume fraction. A simple geometric shape (ellipsoidal) is assumed for both ice crystals and air inclusions. This kind of shape is reasonable for the purpose of the dielectric study. The result is a mixture, smoothly changing from firn particles in air (low density) to air bubbles in an ice matrix (high density). A statistical analysis has been accomplished to investigate the dependence of the dielectric properties on the geometrical arrangement of the inclusions. For that purpose, a large number of simulations with different arrangements (micro−states) giving rise to the same average density (macro−states) has been carried out. The permittivity change due to micro−state variability appears to be at least two−three times the model variation due to density alone, and comparable to the measured variability at a given depth, suggesting that firn structure has a significant effect on the dielectric properties. |
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1110 |
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Series Issue |
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Edition |
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| ISSN |
0165-232X |
ISBN |
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Medium |
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Expedition |
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Conference |
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Approved |
yes |
| Call Number |
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Serial |
7995 |
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| Author |
A. Baranov, R. Tenzer, A. Morelli |
| Title |
Updated Antarctic crustal model |
Type |
Journal |
| Year |
2021 |
Publication |
Gondwana Research |
Abbreviated Journal |
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| Volume |
89 |
Issue |
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Pages |
1-18 |
| Keywords |
Antarctica Crustal structure Gondwana Sediments |
| Abstract |
We use seismic data together with a subglacial bedrock relief from the BEDMAP2 database to obtain a new three-layer model of the consolidated (crystalline) crust of Antarctica that locally improves the global seismic crustal model CRUST1.0. We collect suitable data for constructing crustal layers, analyse them and build maps of the crustal layer thickness and seismic velocities. We use the subglacial relief according to a tectonic configuration and then interpolate data using a statistical kriging method. The P-wave velocity information from old seismic profiles have been supplemented with the new shear-wave velocity models. We adjust the thickness of crustal layers by multiplying a total crustal thickness by a percentage ratio of each individual layer at each point. Our results reveal large variations in seismic velocities between different crustal blocks forming Antarctica. The most pronounced differences exist between East and West Antarctica. In East Antarctica, a high P-wave velocity (vP > 7 km/s) layer in the lower crust is absent. The P-wave velocity in the lower crust changes from 6.1 km/s beneath the Lambert Rift to 6.9 km/s beneath the Wilkes Basin. In West Antarctica, a thick mafic lower crust is characterized by large P-wave velocities, ranging from 7.0 km/s under the Ross Sea to 7.3 km/s under the Byrd Basin. In contrast, velocities in the lower crust beneath the Transantarctic and Ellsworth-Whitmore Mountains are ~6.8 km/s. The P-wave velocities in the upper crust in East Antarctica are within the range 5.5–6.4 km/s. The upper crust of West Antarctica is characterized by the P-wave velocities of 5.6–6.3 km/s. The P-wave velocities in the middle crust vary within 5.9–6.6 km/s in East Antarctica and within 6.3–6.5 km/s in West Antarctica. A low-velocity layer (5.8–5.9 km/s) is detected at depth of ~20–25 km beneath the Princes Elizabeth Land. |
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133 |
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Series Title |
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Abbreviated Series Title |
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Series Issue |
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Edition |
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| ISSN |
1342-937X |
ISBN |
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Medium |
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Expedition |
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Conference |
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| Notes |
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Approved |
yes |
| Call Number |
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Serial |
7994 |
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| Author |
Fanny Larue, Ghislain Picard, Jérémie Aublanc, Laurent Arnaud, Alvaro Robledano-Perez, Emmanuel LE Meur, Vincent Favier, Bruno Jourdain, Joel Savarino, Pierre Thibaut |
| Title |
Radar altimeter waveform simulations in Antarctica with the Snow Microwave Radiative Transfer Model (SMRT) |
Type |
Journal |
| Year |
2021 |
Publication |
Remote Sensing of Environment |
Abbreviated Journal |
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| Volume |
263 |
Issue |
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Pages |
112534 |
| Keywords |
Antarctic ice sheet Field measurements Modeling Radar altimetry Remote sensing SMRT Waveform |
| Abstract |
Radar altimeters are important tools to monitor the volume of the ice sheets. The penetration of radar waves in the snowpack is a major source of uncertainty to retrieve surface elevation. To correct this effect, a better understanding of the sensitivity of the radar waveforms to snow properties is needed. Here, we present an extension of the Snow Model Radiative Transfer (SMRT) to compute radar waveforms and conduct a series of simulations on the Antarctic ice sheet. SMRT is driven by snow and surface roughness properties measured over a large latitudinal range during two field campaigns on the Antarctic Plateau. These measurements show that the snowpack is rougher, denser, less stratified, warmer, and has smaller snow grains near the coast than on the central Plateau. These simulations are compared to satellite observations in the Ka, Ku, and S bands. SMRT reproduces the observed waveforms well. For all sites and all sensors, the main contribution comes from the surface echo. The echo from snow grains (volume scattering) represents up to 40% of the amplitude of the total waveform power in the Ka band, and less at the lower frequencies. The highest amplitude is observed on the central Plateau due to the combination of higher reflection from the surface, higher scattering by snow grains in the Ka and Ku bands, and higher inter-layer reflections in the S band. In the Ka band, the wave penetrates in the snowpack less deeply on the central Plateau than near the coast because of the strong scattering caused by the larger snow grains. The opposite is observed in the S band, the wave penetrates deeper on the central Plateau because of the lower absorption due to the lower snow temperatures. The elevation bias caused by wave penetration into the snowpack show a constant bias of 10 cm for all sites in the Ka band, and a bias of 11 cm, and 21 cm in the Ku band for sites close to the coast and the central Plateau, respectively. Now that SMRT is performing waveform simulations, further work will address how the snowpack properties affect the parameters retrieved by more advanced retracking algorithms such as ICE-2 for different snow cover surfaces. |
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1110 |
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| ISSN |
0034-4257 |
ISBN |
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Approved |
yes |
| Call Number |
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Serial |
7997 |
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| Author |
Pierre-Yves Pascal, Yann Reynaud, Elie Poulin, Chantal De Ridder, Thomas Saucede |
| Title |
Feeding in spatangoids: the case of Abatus Cordatus in the Kerguelen Islands (Southern Ocean) |
Type |
Journal |
| Year |
2021 |
Publication |
Polar Biology |
Abbreviated Journal |
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| Volume |
44 |
Issue |
4 |
Pages |
795-808 |
| Keywords |
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| Abstract |
Irregular urchins exclusively live in marine soft bottom habitats, dwelling either upon or inside sediments and selectively picking up sediment grains and organic particles, or swallowing bulk sediment to feed on the associated organic matter. The exact food source and dietary requirements of most irregular echinoids, however, remain incompletely understood. The schizasterid species Abatus cordatus (Verrill, 1876) is a sub-Antarctic spatangoid that is endemic to the Kerguelen. The feeding behaviour of A. cordatus was investigated using simultaneously metabarcoding and stable isotope approaches. Comparison of ingested and surrounding sediments by metabarcoding revealed a limited selective ingestion of prokaryotes and eukaryotes by the urchin. Compared to surrounding sediments, the gut content had (i) higher carbon and nitrogen concentrations potentially due to selective ingestion of organic matter and/or the sea urchin mucus secretion and (ii) δ15N enrichment due to the selective assimilation of lighter isotope in the gut. Feeding experiments were performed using 13C and 15 N-enriched sediments in aquariums. The progression of stable isotope enrichment in proximal and distal parts of the digestive track of A. cordatus revealed that all particles are not similarly transported likely due to siphon functioning. Ingestion of water with associated dissolved and particulate organic matter should play an important role in urchin nutrition. A. cordatus had a gut resident time fluctuating between 76 and 101 h and an ingestion rate of 36 mg dry sediment h−1 suggesting that dense populations of the species may play a key ecological role through bioturbation in soft bottom shallow-water habitats of the Kerguelen Islands. |
| Programme |
1044 |
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Series Issue |
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Edition |
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| ISSN |
1432-2056 |
ISBN |
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| Area |
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Expedition |
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| Notes |
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Approved |
yes |
| Call Number |
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Serial |
8000 |
| Permanent link to this record |
