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Author |
Johanna Faure, Clara Péron, Nicolas Gasco, Félix Massiot-Granier, Jérôme Spitz, Christophe Guinet, Paul Tixier |
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Title  |
Contribution of toothfish depredated on fishing lines to the energy intake of killer whales off the Crozet Islands: a multi-scale bioenergetic approach |
Type |
Journal |
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Year |
2021 |
Publication |
Marine Ecology Progress Series |
Abbreviated Journal |
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Volume |
668 |
Issue |
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Pages |
149-161 |
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Keywords |
Bioenergetic model Depredation Dissostichus eleginoides Ecosystem-based management Fisheries interaction Marine mammals Orcinus orca Top predator conservation |
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Abstract |
Fisheries modify prey availability for marine predators by extracting resources but also by providing them with new feeding opportunities. Among these, depredation, which occurs when predators feed on fish caught on fishing gear, is a behavior developed by many species as a way to acquire food through limited foraging effort. However, the extent to which depredated resources from fisheries contribute to the energetic requirements and affect the demography of depredating individuals is unknown. We investigated the contribution of Patagonian toothfish Dissostichus eleginoides depredated on longlines to the energetic requirements of killer whales Orcinus orca around the Crozet Islands (southern Indian Ocean) over the period 2007-2018. Our results indicate that during days when depredation occurred, depredating individuals fulfilled on average 94.1% of their daily energetic requirements with depredated toothfish. However, the contribution varied from 1.2 to 13.3% of the monthly energetic requirements and from 2.4 to 8.8% of the yearly energetic requirements of the total population. Together, these findings suggest that intake of depredated toothfish can be substantial at a fine scale (daily and individually), potentially leading to temporary provisioning effects and changes in predation pressures. These effects become minor (<10%), however, when considering the full population over a whole year. The contribution of depredated fish to the annual energetic requirements of the population has increased in recent years, likely due to larger fishing quotas and greater opportunities for whales to depredate, which stresses the importance of accounting for depredation in ecosystem-based management of fishing activity. |
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109 |
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0171-8630, 1616-1599 |
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yes |
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8335 |
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Marina Renedo, David Amouroux, Céline Albert, Sylvain Bérail, Vegard S. Bråthen, Maria Gavrilo, David Grémillet, Hálfdán H. Helgason, Dariusz Jakubas, Anders Mosbech, Hallvard Strøm, Emmanuel Tessier, Katarzyna Wojczulanis-Jakubas, Paco Bustamante, Jérôme Fort |
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Title |
Contrasting Spatial and Seasonal Trends of Methylmercury Exposure Pathways of Arctic Seabirds: Combination of Large-Scale Tracking and Stable Isotopic Approaches |
Type |
Journal |
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Year |
2021 |
Publication |
Environmental Science & Technology |
Abbreviated Journal |
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Volume |
54 |
Issue |
21 |
Pages |
13619-13629 |
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Abstract |
Despite the limited direct anthropogenic mercury (Hg) inputs in the circumpolar Arctic, elevated concentrations of methylmercury (MeHg) are accumulated in Arctic marine biota. However, the MeHg production and bioaccumulation pathways in these ecosystems have not been completely unraveled. We measured Hg concentrations and stable isotope ratios of Hg, carbon, and nitrogen in the feathers and blood of geolocator-tracked little auk Alle alle from five Arctic breeding colonies. The wide-range spatial mobility and tissue-specific Hg integration times of this planktivorous seabird allowed the exploration of their spatial (wintering quarters/breeding grounds) and seasonal (nonbreeding/breeding periods) MeHg exposures. An east-to-west increase of head feather Hg concentrations (1.74–3.48 μg·g–1) was accompanied by significant spatial trends of Hg isotope (particularly Δ199Hg: 0.96–1.13‰) and carbon isotope (δ13C: −20.6 to −19.4‰) ratios. These trends suggest a distinct mixing/proportion of MeHg sources between western North Atlantic and eastern Arctic regions. Higher Δ199Hg values (+0.4‰) in northern colonies indicate an accumulation of more photochemically impacted MeHg, supporting shallow MeHg production and bioaccumulation in high Arctic waters. The combination of seabird tissue isotopic analysis and spatial tracking helps in tracing the MeHg sources at various spatio-temporal scales. |
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388 |
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0013-936X |
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yes |
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Serial |
8023 |
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Author |
Stine Frey Laursen, Laura Skrubbeltrang Hansen, Simon Bahrndorff, Hanne Marie Nielsen, Natasja Krog Noer, David Renault, Goutam Sahana, Jesper Givskov Sørensen, Torsten Nygaard Kristensen |
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Title |
Contrasting Manual and Automated Assessment of Thermal Stress Responses and Larval Body Size in Black Soldier Flies and Houseflies |
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Journal |
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Year |
2021 |
Publication |
Insects |
Abbreviated Journal |
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Volume |
12 |
Issue |
5 |
Pages |
380 |
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Keywords |
Hermetia illucens Musca domestica acclimation automated phenotyping heat and cold tolerance |
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Abstract |
Within ecophysiological and genetic studies on insects, morphological and physiological traits are commonly assessed and phenotypes are typically obtained from manual measurements on numerous individuals. Manual observations are, however, time consuming, can introduce observer bias and are prone to human error. Here, we contrast results obtained from manual assessment of larval size and thermal tolerance traits in black soldier flies (Hermetia illucens) and houseflies (Musca domestica) that have been acclimated under three different temperature regimes with those obtained automatically using an image analysis software (Noldus EthoVision XT). We found that (i) larval size estimates of both species, obtained by manual weighing or by using the software, were highly correlated, (ii) measures of heat and cold tolerance using manual and automated approaches provided qualitatively similar results, and (iii) by using the software we obtained quantifiable information on stress responses and acclimation effects of potentially higher ecological relevance than the endpoint traits that are typically assessed when manual assessments are used. Based on these findings, we argue that automated assessment of insect stress responses and largescale phenotyping of morphological traits such as size will provide new opportunities within many disciplines where accurate and largescale phenotyping of insects is required. |
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136 |
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ISSN |
2075-4450 |
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yes |
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Serial |
8299 |
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Author |
Guillaume Hubert |
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Title |
Continuously Measurements of Energy Spectra of Cosmic-Ray-induced-neutrons on the Concordia Antarctic Station for the period 2015-2021 |
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Journal |
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Year |
2021 |
Publication |
Proceedings of 37th International Cosmic Ray Conference — PoS(ICRC2021) |
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Volume |
395 |
Issue |
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Pages |
1263 |
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Abstract |
The CHINSTRAP (Continuous High-altitude Investigation of the Neutron Spectra for Terrestrial Radiation Antarctic Project) supported by the French Polar Agency (IPEV) aims at recording cosmic-ray (CR) induced-neutron spectra at the Concordia station since December 2015. The neutron spectrometer measures the neutron spectrum over a wide energy range from meV up to tens of GeV with a short time resolution. Several parameters can influence the measurement, including systematic and environmental effects such as the atmospheric pressure, the hydrometric environment close to the instrument and the atmospheric water vapor. This paper presents CR induced neutrons measurements analyses from 2015 to 2021 in Concordia, integrating corrections to take into account environmental and systematic effects. Long-term and short-term analyses are proposed, applied to count rate, fluxes and spectra. A last part investigates the contribution of modelling to data analyses and the ability to deduce the solar modulation from neutron spectra and the radiation field extrapolation using nuclear transport in atmosphere. An underlying objective is also to improve physical models allowing analyses of continuous and simultaneously measurements of CR induced neutrons spectra. |
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1112 |
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yes |
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Serial |
8516 |
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Author |
Charlène Gémard, Víctor Planas-Bielsa, Francesco Bonadonna, Thierry Aubin |
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Title |
Contextual variations in calls of two nonoscine birds: the blue petrel Halobaena caerulea and the Antarctic prion Pachyptila desolata |
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Journal |
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Year |
2021 |
Publication |
Behavioral Ecology |
Abbreviated Journal |
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Volume |
32 |
Issue |
4 |
Pages |
769-779 |
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Abstract |
Bird vocalizations are critical cues in social interactions as they convey temporary information varying with the social context, for example, the signaler motivation when facing a rival or a potential mate. To date, literature mainly focused on learning birds. Burrowing petrels (Procellariidae) are nonlearning birds with a limited vocal repertoire. Bachelor males communicate with conspecifics with a single call emitted in three situations: in the absence of a certain auditory (spontaneous calls), toward females (female-directed calls), and toward males (male-directed calls). We first hypothesized that, although the call structure is preserved, temporal and spectral parameters vary between the three call types of bachelor males, translating different motivations (Motivation Hypothesis). To go further, we hypothesized that acoustic variations in male-directed calls indicate the signaler’s aggressive motivation and, therefore, the variations are similar whether calls are produced by breeder or bachelor males (Breeding Status Hypothesis). We tested the two hypotheses performing field playback experiments on two petrel species: the blue petrel (Halobaena caerulea) and the Antarctic prion (Pachyptila desolata). Despite the obvious call stereotypy, we observed temporal variations and frequency shifts when males react to a female or a male, which may translate the sexual or aggressive motivation of the signaler. Furthermore, the similarity of variations in male-directed calls of both breeder and bachelor males suggests the aggressive motivation. So far, vocal plasticity in nonlearning birds has been greatly underestimated. Here, we highlighted the expression of different motivations through vocal variations and the ability to produce frequency variations in species with genetically coded vocalizations. |
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Programme |
354 |
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ISSN |
1045-2249 |
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yes |
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Serial |
8259 |
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Author |
Chastel O., Blévin P., Humann‑Guilleminot S., Helfenstein F., Tartu S., Angelier F., Sebastiano M., Costantini D., Shaffer S., Bustamante P., Labadie P., Budzinski H., Herzke D., Moe B., Bustnes J.O., Gabrielsen G.W. |
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Title |
Contaminants of growing concern: Poly- and Perfluoroalkylated Substances (PFAS) and their physiological consequences in seabirds |
Type |
Peer-reviewed symposium |
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Year |
2021 |
Publication |
World seabird conference virtual meeting, October 4-8, 2021 |
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Programme |
330 |
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Approved |
yes |
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Serial |
8334 |
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Author |
Thomas Frederikse, Surendra Adhikari, Tim J. Daley, Sönke Dangendorf, Roland Gehrels, Felix Landerer, Marta Marcos, Thomas L. Newton, Graham Rush, Aimée B. A. Slangen, Guy Wöppelmann |
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Title |
Constraining 20th-Century Sea-Level Rise in the South Atlantic Ocean |
Type |
Journal |
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Year |
2021 |
Publication |
Journal of Geophysical Research: Oceans |
Abbreviated Journal |
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Volume |
126 |
Issue |
3 |
Pages |
e2020JC016970 |
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Keywords |
data rescue salt-marsh proxies sea-level changes South Atlantic tide gauges |
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Abstract |
Sea level in the South Atlantic Ocean has only been measured at a small number of tide-gauge locations, which causes considerable uncertainty in 20th-century sea-level trend estimates in this basin. To obtain a better-constrained sea-level trend in the South Atlantic Ocean, this study aims to answer two questions. The first question is: can we combine new observations, vertical land motion estimates, and information on spatial sampling biases to obtain a likely range of 20th-century sea-level rise in the South Atlantic? We combine existing observations with recovered observations from Dakar and a high-resolution sea-level reconstruction based on salt-marsh sediments from the Falkland Islands and find that the rate of sea-level rise in the South Atlantic has likely been between 1.1 and 2.2 mm year−1 (5%–95% confidence intervals), with a central estimate of 1.6 mm year−1. This rate is on the high side, but not statistically different compared to global-mean trends from recent reconstructions. The second question is: are there any physical processes that could explain a large deviation from the global-mean sea-level trend in the South Atlantic? Sterodynamic (changes in ocean dynamics and steric effects) and gravitation, rotation, and deformation effects related to ice mass loss and land water storage have probably led to a 20th-century sea-level trend in the South Atlantic above the global mean. Both observations and physical processes thus suggest that 20th-century sea-level rise in the South Atlantic has been about 0.3 mm year−1 above the rate of global-mean sea-level rise, although even with the additional observations, the uncertainties are still too large to distinguish a statistically significant difference. |
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Programme |
688 |
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ISSN |
2169-9291 |
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yes |
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Serial |
8603 |
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Author |
Hajo Eicken, Finn Danielsen, Josephine-Mary Sam, Maryann Fidel, Noor Johnson, Michael K Poulsen, Olivia A Lee, Katie V Spellman, Lisbeth Iversen, Peter Pulsifer, Martin Enghoff |
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Title |
Connecting Top-Down and Bottom-Up Approaches in Environmental Observing |
Type |
Journal |
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Year |
2021 |
Publication |
BioScience |
Abbreviated Journal |
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Volume |
71 |
Issue |
5 |
Pages |
467-483 |
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Abstract |
Effective responses to rapid environmental change rely on observations to inform planning and decision-making. Reviewing literature from 124 programs across the globe and analyzing survey data for 30 Arctic community-based monitoring programs, we compare top-down, large-scale program driven approaches with bottom-up approaches initiated and steered at the community level. Connecting these two approaches and linking to Indigenous and local knowledge yields benefits including improved information products and enhanced observing program efficiency and sustainability. We identify core principles central to such improved links: matching observing program aims, scales, and ability to act on information; matching observing program and community priorities; fostering compatibility in observing methodology and data management; respect of Indigenous intellectual property rights and the implementation of free, prior, and informed consent; creating sufficient organizational support structures; and ensuring sustained community members’ commitment. Interventions to overcome challenges in adhering to these principles are discussed. |
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Programme |
1090,1206 |
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Thesis |
Bachelor's thesis |
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ISSN |
0006-3568 |
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yes |
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Call Number |
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Serial |
8249 |
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Author |
Steven Franke, Daniela Jansen, Sebastian Beyer, Niklas Neckel, Tobias Binder, John Paden, Olaf Eisen |
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Title |
Complex Basal Conditions and Their Influence on Ice Flow at the Onset of the Northeast Greenland Ice Stream |
Type |
Journal |
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Year |
2021 |
Publication |
Journal of Geophysical Research: Earth Surface |
Abbreviated Journal |
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Volume |
126 |
Issue |
3 |
Pages |
e2020JF005689 |
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Keywords |
basal roughness bed conditions Greenland Ice Sheet ice stream Northeast Greenland Ice Stream radio-echo sounding |
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Abstract |
Abstract The ice stream geometry and large ice surface velocities at the onset region of the Northeast Greenland Ice Stream (NEGIS) are not yet well reproduced by ice sheet models. The quantification of basal sliding and a parametrization of basal conditions remains a major gap. In this study, we assess the basal conditions of the onset region of the NEGIS in a systematic analysis of airborne ultra-wideband radar data. We evaluate basal roughness and basal return echoes in the context of the current ice stream geometry and ice surface velocity. We observe a change from a smooth to a rougher bed where the ice stream widens, and a distinct roughness anisotropy, indicating a preferred orientation of subglacial structures. In the upstream region, the excess ice mass flux through the shear margins is evacuated by ice flow acceleration and along-flow stretching of the ice. At the downstream part, the generally rougher bed topography correlates with a decrease in flow acceleration and lateral variations in ice surface velocity. Together with basal water routing pathways, this hints to two different zones in this part of the NEGIS: the upstream region collecting water, with a reduced basal traction, and downstream, where the ice stream is slowing down and is widening on a rougher bed, with a distribution of basal water toward the shear margins. Our findings support the hypothesis that the NEGIS is strongly interconnected to the subglacial water system in its onset region, but also to the subglacial substrate and morphology. |
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Programme |
1180 |
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ISSN |
2169-9003 |
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yes |
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Call Number |
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Serial |
7272 |
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Author |
Gareth Chisham, Angeline G. Burrell, Aurélie Marchaudon, Simon G. Shepherd, Evan G. Thomas, Pasha Ponomarenko |
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Title |
Comparison of interferometer calibration techniques for improved SuperDARN elevation angles |
Type |
Journal |
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Year |
2021 |
Publication |
Polar Science |
Abbreviated Journal |
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Volume |
28 |
Issue |
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Pages |
100638 |
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Keywords |
Geolocation HF radar Interferometer calibration Ionosphere SuperDARN |
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Abstract |
The high frequency radars in the Super Dual Auroral Radar Network (SuperDARN) estimate the elevation angles of returned backscatter using interferometric techniques. These elevation angles allow the ground range to the scattering point to be estimated, which is crucial for the accurate geolocation of ionospheric measurements. For elevation angles to be accurately estimated, it is important to calibrate the interferometer measurements by determining the difference in the signal time delays caused by the difference in the electrical path lengths from the main array and the interferometer array to the point at which the signals are correlated. This time delay is known as tdiff. Several methods have been proposed to estimate tdiff using historical observations; these methods are summarised in this paper. Comparisons of the tdiff estimates from the different calibration methods are presented and sources of uncertainty discussed. The effect of errors in the estimated tdiff value on the accuracy of geolocation is evaluated and discussed. The paper concludes with a series of recommendations for both scientific SuperDARN data users and SuperDARN radar operators. |
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312 |
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ISSN |
1873-9652 |
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yes |
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Call Number |
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Serial |
8088 |
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| Permanent link to this record |
