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Ana P. B. Carneiro, Elizabeth J. Pearmain, Steffen Oppel, Thomas A. Clay, Richard A. Phillips, Anne-Sophie Bonnet‐Lebrun, Ross M. Wanless, Edward Abraham, Yvan Richard, Joel Rice, Jonathan Handley, Tammy E. Davies, Ben J. Dilley, Peter G. Ryan, Cleo Small, Javier Arata, John P. Y. Arnould, Elizabeth Bell, Leandro Bugoni, Letizia Campioni, Paulo Catry, Jaimie Cleeland, Lorna Deppe, Graeme Elliott, Amanda Freeman, Jacob González‐Solís, José Pedro Granadeiro, David Grémillet, Todd J. Landers, Azwianewi Makhado, Deon Nel, David G. Nicholls, Kalinka Rexer‐Huber, Christopher J. R. Robertson, Paul M. Sagar, Paul Scofield, Jean-Claude Stahl, Andrew Stanworth, Kim L. Stevens, Philip N. Trathan, David R. Thompson, Leigh Torres, Kath Walker, Susan M. Waugh, Henri Weimerskirch, Maria P. Dias. (2020). A framework for mapping the distribution of seabirds by integrating tracking, demography and phenology (Vol. 57).
Abstract: The identification of geographic areas where the densities of animals are highest across their annual cycles is a crucial step in conservation planning. In marine environments, however, it can be particularly difficult to map the distribution of species, and the methods used are usually biased towards adults, neglecting the distribution of other life-history stages even though they can represent a substantial proportion of the total population. Here we develop a methodological framework for estimating population-level density distributions of seabirds, integrating tracking data across the main life-history stages (adult breeders and non-breeders, juveniles and immatures). We incorporate demographic information (adult and juvenile/immature survival, breeding frequency and success, age at first breeding) and phenological data (average timing of breeding and migration) to weight distribution maps according to the proportion of the population represented by each life-history stage. We demonstrate the utility of this framework by applying it to 22 species of albatrosses and petrels that are of conservation concern due to interactions with fisheries. Because juveniles, immatures and non-breeding adults account for 47%–81% of all individuals of the populations analysed, ignoring the distributions of birds in these stages leads to biased estimates of overlap with threats, and may misdirect management and conservation efforts. Population-level distribution maps using only adult distributions underestimated exposure to longline fishing effort by 18%–42%, compared with overlap scores based on data from all life-history stages. Synthesis and applications. Our framework synthesizes and improves on previous approaches to estimate seabird densities at sea, is applicable for data-poor situations, and provides a standard and repeatable method that can be easily updated as new tracking and demographic data become available. We provide scripts in the R language and a Shiny app to facilitate future applications of our approach. We recommend that where sufficient tracking data are available, this framework be used to assess overlap of seabirds with at-sea threats such as overharvesting, fisheries bycatch, shipping, offshore industry and pollutants. Based on such an analysis, conservation interventions could be directed towards areas where they have the greatest impact on populations.
Keywords: albatrosses at-sea threats conservation distributions longline fisheries megafauna petrels seabird density
Programme: 388
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Agnieszka Beszczynska-Möller, Hanne Sagen, Peter Voss, Mikael K. Sejr, Thomas Soltwedel, Truls Johannessen, M.-N. Houssais, Andreas Rogge, Ian Allan, Frank Nilsen, Angelika Renner, L. H. Smedsrud, Nicholas Roden, Jean-Pierre Gattuso, Laurent Chauvaud, Claudie Marec, B. Cheng, Andrew King, Christine Provost, Marcel Babin, Mathilde Sorensen. (2020). Enhancement of ocean and sea ice in situ observations in the Arctic under the Horizon2020 project INTAROS.
Abstract: The H2020 project Integrated Arctic Observation System (INTAROS) aspires to increase the temporal and geographic coverage of in situ observations and add new key geophysical and biogeochemical variables in selected regions of the Arctic. By using a combination of mature and new instruments and sensors in integration with existing observatories, INTAROS aims to fill selected gaps in the present-day system and build additional capacity of the Arctic monitoring networks for ocean and sea ice. Three reference sites have been selected as key locations for monitoring ongoing Arctic changes: Costal Greenland, paramount for freshwater output from the Greenland ice sheet; North of Svalbard (covering the region from shelf to deep basin) – the hot-spot for ocean-air-sea ice interactions, and heat and biological energy input to the European Arctic; and Fram Strait – the critical gateway for exchanges between the Arctic and the World oceans. The existing observatories in the reference sites have been extended with new moorings and novel autonomous instrumentation, in particular for biogeochemical measurements and sea ice observations. Bottom-mounted instruments have been also implemented for seismic observations. A distributed observatory for ocean and sea ice in the Arctic Ocean and sub-Arctic seas includes non-stationary components such as ice-tethered observing platforms, float, gliders, and ships of opportunities, collecting multidisciplinary observations, still missing from the Arctic regions. New sensors, integrated platforms and experimental set-ups are currently under implementation during a two-year long deployment phase (2018-2020) with an aim to evaluate their sustained use in a future iAOS. New observations will be used for integration of new data products, demonstration studies and stakeholder consultations, contributing also to ongoing and future long-term initiatives (e.g. SAON).
Programme: 1141
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Niels M. Schmidt, Bess Hardwick, Olivier Gilg, Toke T. Høye, Paul Henning Krogh, Hans Meltofte, Anders Michelsen, Jesper B. Mosbacher, Katrine Raundrup, Jeroen Reneerkens, Lærke Stewart, Helena Wirta, Tomas Roslin. (2017). Interaction webs in arctic ecosystems: Determinants of arctic change? (Vol. 46).
Abstract: How species interact modulate their dynamics, their response to environmental change, and ultimately the functioning and stability of entire communities. Work conducted at Zackenberg, Northeast Greenland, has changed our view on how networks of arctic biotic interactions are structured, how they vary in time, and how they are changing with current environmental change: firstly, the high arctic interaction webs are much more complex than previously envisaged, and with a structure mainly dictated by its arthropod component. Secondly, the dynamics of species within these webs reflect changes in environmental conditions. Thirdly, biotic interactions within a trophic level may affect other trophic levels, in some cases ultimately affecting land–atmosphere feedbacks. Finally, differential responses to environmental change may decouple interacting species. These insights form Zackenberg emphasize that the combination of long-term, ecosystem-based monitoring, and targeted research projects offers the most fruitful basis for understanding and predicting the future of arctic ecosystems.
Programme: 1036
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A. El Yazidi, M. Ramonet, P. Ciais, G. Broquet, I. Pison, A. Abbaris, D. Brunner, S. Conil, M. Delmotte, F. Gheusi, F. Guerin, L. Hazan, N. Kachroudi, G. Kouvarakis, N. Mihalopoulos, L. Rivier, D. Serça. (2017). Identification of spikes associated with local sources in continuous time series of atmospheric CO, CO2 and CH4 (Vol. 11).
Abstract: This study deals with the problem of identifying atmospheric data influenced by local emissions that can result in spikes in time series of greenhouse gases and long-lived tracer measurements. We considered three spike detection methods known as coefficient of variation (COV), robust extraction of baseline signal (REBS) and standard deviation of the background (SD) to detect and filter positive spikes in continuous greenhouse gas time series from four monitoring stations representative of the European ICOS (Integrated Carbon Observation System) Research Infrastructure network. The results of the different methods are compared to each other and against a manual detection performed by station managers. Four stations were selected as test cases to apply the spike detection methods: a continental rural tower of 100 m height in eastern France (OPE), a high-mountain observatory in the south-west of France (PDM), a regional marine background site in Crete (FKL) and a marine clean-air background site in the Southern Hemisphere on Amsterdam Island (AMS). This selection allows us to address spike detection problems in time series with different variability. Two years of continuous measurements of CO2, CH4 and CO were analysed. All methods were found to be able to detect short-term spikes (lasting from a few seconds to a few minutes) in the time series. Analysis of the results of each method leads us to exclude the COV method due to the requirement to arbitrarily specify an a priori percentage of rejected data in the time series, which may over- or underestimate the actual number of spikes. The two other methods freely determine the number of spikes for a given set of parameters, and the values of these parameters were calibrated to provide the best match with spikes known to reflect local emissions episodes that are well documented by the station managers. More than 96 % of the spikes manually identified by station managers were successfully detected both in the SD and the REBS methods after the best adjustment of parameter values. At PDM, measurements made by two analyzers located 200 m from each other allow us to confirm that the CH4 spikes identified in one of the time series but not in the other correspond to a local source from a sewage treatment facility in one of the observatory buildings. From this experiment, we also found that the REBS method underestimates the number of positive anomalies in the CH4 data caused by local sewage emissions. As a conclusion, we recommend the use of the SD method, which also appears to be the easiest one to implement in automatic data processing, used for the operational filtering of spikes in greenhouse gases time series at global and regional monitoring stations of networks like that of the ICOS atmosphere network.
Programme: 416
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A. Saintenoy, J.-M. Friedt, A. D. Booth, F. Tolle, E. Bernard, D. Laffly, C. Marlin, M. Griselin. (2012). Deriving ice thickness, glacier volume and bedrock morphology of Austre Lovénbreen (Svalbard) using GPR (Vol. 11).
Abstract: Austre Lovénbreen is a 4.6 km2 glacier on the Archipelago of Svalbard (79o N) that has been surveyed over the last 47 years in order to monitor in particular the glacier evolution and associated hydrological phenomena in the context of nowadays global warming. A three-week field survey during April 2010 allowed for the acquisition of a dense mesh of ground-penetrating radar (GPR) data with an average of 14 683 points per km2 (67 542 points total) on the glacier surface. The profiles were acquired using Malå equipment with 100 MHz antennas, towed slowly enough to record on average every 0.3 m, a trace long enough to sound down to 189 m of ice. One profile was repeated with a 50 MHz antenna set to improve electromagnetic wave propagation depth in scattering media observed in the cirques closest to the slopes. The GPR was coupled to a GPS system to position traces. Each profile was manually edited using standard GPR data processing including migration, to pick the reflection arrival time from the ice-bedrock interface. Snow cover was evaluated through 42 snow drilling measurements regularly spaced to cover the entire glacier. These data were acquired at the time of the GPR survey and subsequently spatially interpolated using ordinary kriging. Using a snow velocity of 0.22 m/ns, the snow thickness was converted to electromagnetic wave traveltimes and subtracted from the picked traveltimes to the ice-bedrock interface. The resulting traveltimes were converted to ice thickness using a velocity of 0.17 m/ns. The velocity uncertainty is discussed from a common midpoint profile analysis. A total of 67 542 geo-referenced data points with GPR-derived ice thicknesses, in addition to a glacier boundary line derived from satellite images taken during summer, were interpolated over the entire glacier surface using kriging with a 10 m grid size. Some uncertainty analyses were carried out and we calculated an averaged ice thickness of 76 m and a maximum depth of 164 m with a relative error of 11.9%. The volume of the glacier is derived as 0.3487 ± 0.041 km3. Finally a 10 m grid map of the bedrock topography was derived by subtracting the ice thicknesses from a dual-frequency GPSderived digital elevation model of the surface. These two data sets are the first step for modelling thermal evolution of a glacier and its bedrock, as well as the main hydrological network.
Programme: 1108
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D. Laffly, É Bernard, M. Griselin, F. Tolle, J.-M. Friedt, G. Martin, C. Marlin. (2012). High temporal resolution monitoring of snow cover using oblique view ground-based pictures (Vol. 48).
Abstract: Due to poor weather conditions including common heavy cloud cover at polar latitudes, daily satellite imaging is not always accessible. Nevertheless, fast events including heavy rainfall inducing floods appear as significant in the ice and snow budget while being ignored by satellite based studies since the slower sampling rate is unable to observe such short phenomena. We complement satellite imagery with a set of ground based autonomous automated high resolution digital cameras. The recorded oblique views, acquired at a rate of 3 images per day, are processed for comparison with the spaceborne imagery. Delaunay triangulation based mapping using a dense set of reference points provides the means for an accurate projection by applying a rubber sheeting algorithm. The measurement strategy of identifying binary information of ice and snow cover is illustrated through the example of a particular flood event. We observe a snow cover evolution from 100% to 44.5% and back to 100% over a period of 2 weeks.
Programme: 1108
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J.-M. Friedt, F. Tolle, É Bernard, M. Griselin, D. Laffly, C. Marlin. (2012). Assessing the relevance of digital elevation models to evaluate glacier mass balance: application to Austre Lovénbreen (Spitsbergen, 79°N) (Vol. 48).
Abstract: The volume variation of a glacier is the actual indicator of long term and short term evolution of the glacier behaviour. In order to assess the volume evolution of the Austre Lovénbreen (79° N) over the last 47 years, we used multiple historical datasets, complemented with our high density GPS tracks acquired in 2007 and 2010. The improved altitude resolution of recent measurement techniques, including phase corrected GPS and LiDAR, reduces the time interval between datasets used for volume subtraction in order to compute the mass balance. We estimate the sub-metre elevation accuracy of most recent measurement techniques to be sufficient to record ice thickness evolutions occurring over a 3 year duration at polar latitudes.The systematic discrepancy between ablation stake measurements and DEM analysis, widely reported in the literature as well as in the current study, yields new questions concerning the similarity and relationship between these two measurement methods.The use of Digital Elevation Model (DEM) has been an attractive alternative measurement technique to estimate glacier area and volume evolution over time with respect to the classical in situ measurement techniques based on ablation stakes. With the availability of historical datasets, whether from ground based maps, aerial photography or satellite data acquisition, such a glacier volume estimate strategy allows for the extension of the analysis duration beyond the current research programmes. Furthermore, these methods do provide a continuous spatial coverage defined by its cell size whereas interpolations based on a limited number of stakes display large spatial uncertainties. In this document, we focus on estimating the altitude accuracy of various datasets acquired between 1962 and 2010, using various techniques ranging from topographic maps to dual frequency skidoo-tracked GPS receivers and the classical aerial and satellite photogrammetric techniques.
Programme: 1108
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Éric Bernard, Jean-Michel Friedt, Gilles Martin, Madeleine Griselin, Christelle Marlin. (2011). La photographie terrestre haute résolution pour quantifier les dynamiques nivales de versants : l’exemple d’un bassin glaciaire arctique (Loven Est – Spitsberg 79°N).
Abstract: Pour comprendre le fonctionnement d’un système glaciaire, l’entrée nivologique est un élément capital. Abordé sur la zone glaciaire, il est assez aisé de quantifier l’information issue de données en télédétection et mesures in situ afin d’obtenir la fraction de couverture neigeuse ou de glace vive, nombre et surface couverte par les avalanches, reptation de la neige et autres effets dynamiques du manteau neigeux. En revanche, quantifier l’information issue des versants s’avère beaucoup plus délicat : les surfaces réelles rapportées au plan amputent une grande partie de l’information, d’autant plus que la pente est forte. Cette dernière caractéristique est capitale, puisque les versants ont des pentes moyennes supérieures à 35° et ils représentent un tiers de la superficie du bassin étudié. Dans ces conditions, la photographie au sol peut permettre d’extrapoler de l’information quantitative à partir de clichés qualitatifs. Dans le cadre du programme Hydro-Sensor-FLOWS (2006-2010), un réseau de capteurs équipe le glacier Loven Est (5 km2), sur la côte occidentale du Spitsberg (79°N). Des stations photographiques automatiques sont spécialement instal-lées à des points stratégiques du bassin glaciaire pour en couvrir l’intégralité. La rectification pour projection orthogonale des photographies tangentielles est possible : si elle s’avère précieuse pour les zones relativement plates, elle pénalise to-talement l’approche des versants. Le présent article démontre qu’il est possible de tirer de l’information quantitative des photographies non orthorectifiées. En disposant des données nécessaires (Modèle Numérique de Terrain, coordonnées et images satellites), il est possible de déterminer des surfaces à partir de prises de vues in situ. Ce travail démontre la com-plémentarité des images zénithales et des images terrestres tangentielles pour comprendre les processus régissant la dyna-mique des versants., Snow input is a significant element in order to understand a glacier system behaviour. On the glacier area itself, quantifying information coming from remote and in situ sensing is easily performed thanks to the smooth and flat surface. Such quantitative processing is however more complex on the slopes, where effective areas converted to 2D projections hide a great part of the information : the steeper the slope, the larger the correction between projected area and effective area. In the present study, the mean slope angle is 35°, while slopes account for a third of the whole area of the basin. In the frame of the Hydro-Sensor-FlOWS program (2006-2010), a network of sensors has been installed around the Aus-treLovén glacier (5 km2), on the West coast of Svalbard (79°N). Some automated digital cameras are located at strategic places of the glacier basin to cover the whole glacier. While ground based tangential picture geometrical correction is effi-cient on the flattest parts of the glacier, it becomes ineffective on the steep slopes. The present article demonstrates how quantitative information can be recovered even without geometric correction of the pictures. Using the required datasets (digital elevation models, camera coordinates and satellite imagery), in situ pictures provide the snow coverage on the slo-pes. This work demonstrates the complementary use of zenithal and tangential views in order to better understand slope dynamics.
Programme: 1108
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Lutz (C.). (2017). Sibérie : l’énigme iakoute. Film réalisé pour Arte. Diffusion le 3 février 2017 (série “Enquêtes archéologiques”)..
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M. Saunois, P. Bousquet, B. Poulter, A. Peregon, P. Ciais, J. G. Canadell, E. J. Dlugokencky, G. Etiope, D. Bastviken, S. Houweling, G. Janssens-Maenhout, F. N. Tubiello, S. Castaldi, R. B. Jackson, M. Alexe, V. K. Arora, D. J. Beerling, P. Bergamaschi, D. R. Blake, G. Brailsford, L. Bruhwiler, C. Crevoisier, P. Crill, K. Covey, C. Frankenberg, N. Gedney, L. Höglund-Isaksson, M. Ishizawa, A. Ito, F. Joos, H.-S. Kim, T. Kleinen, P. Krummel, J.-F. Lamarque, R. Langenfelds, R. Locatelli, T. Machida, S. Maksyutov, J. R. Melton, I. Morino, V. Naik, S. O'Doherty, F.-J. W. Parmentier, P. K. Patra, C. Peng, S. Peng, G. P. Peters, I. Pison, R. Prinn, M. Ramonet, W. J. Riley, M. Saito, M. Santini, R. Schroeder, I. J. Simpson, R. Spahni, A. Takizawa, B. F. Thornton, H. Tian, Y. Tohjima, N. Viovy, A. Voulgarakis, R. Weiss, D. J. Wilton, A. Wiltshire, D. Worthy, D. Wunch, X. Xu, Y. Yoshida, B. Zhang, Z. Zhang, Q. Zhu. (2017). Variability and quasi-decadal changes in the methane budget over the period 2000–2012 (Vol. 17).
Abstract: Following the recent Global Carbon Project (GCP) synthesis of the decadal methane (CH4) budget over 2000–2012 (Saunois et al., 2016), we analyse here the same dataset with a focus on quasi-decadal and inter-annual variability in CH4 emissions. The GCP dataset integrates results from top-down studies (exploiting atmospheric observations within an atmospheric inverse-modelling framework) and bottom-up models (including process-based models for estimating land surface emissions and atmospheric chemistry), inventories of anthropogenic emissions, and data-driven approaches. The annual global methane emissions from top-down studies, which by construction match the observed methane growth rate within their uncertainties, all show an increase in total methane emissions over the period 2000–2012, but this increase is not linear over the 13 years. Despite differences between individual studies, the mean emission anomaly of the top-down ensemble shows no significant trend in total methane emissions over the period 2000–2006, during the plateau of atmospheric methane mole fractions, and also over the period 2008–2012, during the renewed atmospheric methane increase. However, the top-down ensemble mean produces an emission shift between 2006 and 2008, leading to 22 [16–32] Tg CH4 yr−1 higher methane emissions over the period 2008–2012 compared to 2002–2006. This emission increase mostly originated from the tropics, with a smaller contribution from mid-latitudes and no significant change from boreal regions. The regional contributions remain uncertain in top-down studies. Tropical South America and South and East Asia seem to contribute the most to the emission increase in the tropics. However, these two regions have only limited atmospheric measurements and remain therefore poorly constrained. The sectorial partitioning of this emission increase between the periods 2002–2006 and 2008–2012 differs from one atmospheric inversion study to another. However, all top-down studies suggest smaller changes in fossil fuel emissions (from oil, gas, and coal industries) compared to the mean of the bottom-up inventories included in this study. This difference is partly driven by a smaller emission change in China from the top-down studies compared to the estimate in the Emission Database for Global Atmospheric Research (EDGARv4.2) inventory, which should be revised to smaller values in a near future. We apply isotopic signatures to the emission changes estimated for individual studies based on five emission sectors and find that for six individual top-down studies (out of eight) the average isotopic signature of the emission changes is not consistent with the observed change in atmospheric 13CH4. However, the partitioning in emission change derived from the ensemble mean is consistent with this isotopic constraint. At the global scale, the top-down ensemble mean suggests that the dominant contribution to the resumed atmospheric CH4 growth after 2006 comes from microbial sources (more from agriculture and waste sectors than from natural wetlands), with an uncertain but smaller contribution from fossil CH4 emissions. In addition, a decrease in biomass burning emissions (in agreement with the biomass burning emission databases) makes the balance of sources consistent with atmospheric 13CH4 observations. In most of the top-down studies included here, OH concentrations are considered constant over the years (seasonal variations but without any inter-annual variability). As a result, the methane loss (in particular through OH oxidation) varies mainly through the change in methane concentrations and not its oxidants. For these reasons, changes in the methane loss could not be properly investigated in this study, although it may play a significant role in the recent atmospheric methane changes as briefly discussed at the end of the paper.
Programme: 416
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