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Weill Alain, Eymard Laurence, Vivier Frédéric, Matulka Ania, Loisil Rodrigue, Amarouche Nadir, Panel Jean Michel, Lourenço Antonio, Viola Angelo, Vitale Vito, Argentini Stefania, Kupfer Heike, . (2012). First Observations of Energy Budget and Bulk Fluxes at Ny Ålesund (Svalbard) during a 2010 Transition Period as Analyzed with the BEAR Station
. ISRN Meteorology, 2012, 1–12.
Abstract: A small-size meteorological mast, BEAR (Budget of Energy for Arctic regions) has been developed as a part of a new autonomous buoy for monitoring the sea ice mass balance. BEAR complements observations of the thickness and thermodynamic properties of the ice/snow pack determined by the so-called Ice-T (Ice-Thickness) buoy, giving access to bulk fluxes and energy budget at the surface, using meteorological measurements. The BEAR mast has been tested with success during ten days in April-May 2010 at Ny Alesund, in the Svalbard archipelago (Norway) showing that meteorological data were close to measurements at the same level of the Italian Climate Change Tower (CCT) from the ISAC-CNR. A discussion is undertaken on bulk fluxes determination and uncertainties. Particularly, the strategy to systematically use different relevant fluxes parameterizations is pointed out to explore flux range uncertainty before to analyze energy budget. Net radiation, bulk fluxes and energy budget are estimated using as average 10 minutes, 24 hours and the ten days of the experiment. The observation period was very short, but we observe a spring transition when the net radiation begins to warm the surface while the very small turbulent heat flux cools the surface.
Programme: 1015
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Saucède T, Guillaumot C, Michel L, Fabri-ruiz S, Bazin A, Cabessut M, García-Berro A, Mateos A, Mathieu O, De Ridder C, Dubois P, Danis B, David B, Díaz A, Lepoint G, Motreuil S, Poulin E, Féral Jp. (2019). Modeling species response to climate change in sub-Antarctic islands – Echinoids as a case study for the Kerguelen Plateau..
Abstract: In the Kerguelen Islands, the multiple effects of climate change are expected to impact coastal marine habitats. Species distribution models (SDM) can represent a convenient tool to predict the biogeographic response of species to climate change but biotic interactions are not considered in these models. Nevertheless, new species interactions can emerge in communities exposed to environmental changes and the structure of biotic interactions is directly related to the potential resilience of ecosystems. Trophic interaction studies can help predict species vulnerability to environmental changes using carbon (δ13C) and nitrogen (δ15N) stable isotope ratios to generate trophic models. Using new available data inputs, we generated robust SDM and trophic interaction models to assess the potential response and sensitivity of three echinoid species to future worst-case scenarios of environmental change in the Kerguelen Plateau region. The two modelling approaches provide contrasting insights into the potential responses of each species to future environmental changes with both approaches identifying Abatus cordatus to be particularly vulnerable due to its narrow ecological niche and endemism to near-shore areas. Coupling insights gained from trophic niche ecology with species distribution modelling represents a promising approach that can improve our understanding and ability to predict the potential responses of species to future habitat changes.
Keywords: species distribution model, trophic niche, isotopic niche, biotic interaction, distribution dynamics
Programme: 1044
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Maurice Hullé, Philippe Vernon. (2021). Terrestrial macro-arthropods of the sub-Antarctic islands of Possession (Crozet Archipelago) and Kerguelen: inventory of native and non-native species (Vol. 43).
Abstract: The sub-Antarctic islands of the Southern Ocean harbor biogeographically peculiar biotas which are under threat from climate change, biological invasions and their interactions. Understanding both the indigenous and changing non-indigenous components of these islands is essential for the conservation and management of their biotas. Based on several years of systematic sampling, we present an updated list of terrestrial, free-living macro-invertebrates (insects and spiders) present on the islands of Possession (Crozet Archipelago) and Kerguelen. Ninety-four species were recorded in total on both islands. Forty-one are strictly endemic to one of the two islands, 16 are endemic to the South Indian Ocean Province, and only three were recorded on other sub-Antarctic islands. Beetles and more particularly weevils are the most characteristic group of the fauna of these islands: they include 35 species of which 89% are native and 66% are endemic. One third of the species (30 of 94) are non-indigenous species now naturalized. We discuss these results in terms of biogeography, ecological disharmony and impact of biological invasions.
Programme: 136
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Jean-Pierre Féral, Marc Verlaque, Sebastián Rosenfeld, Elie Poulin, Anne Chenuil, Thomas Saucède. (2021). The Marine Vegetation of the Kerguelen Islands: History of Scientific Campaigns, Inventory of the Flora and First Analysis of Its Biogeographical Affinities (Vol. 42).
Abstract: Conceived as a baseline for the management and conservation of the marine protected area of the French Southern Territories (réserve naturelle nationale des Terres australes françaises), the checklist of marine macroalgae of the Kerguelen Islands was updated based on an extensive review of the literature and scientific databases, from the first report of the Ross expedition, in 1840, to the most recent works. This work was also conceived as a starting point for forthcoming investigations using molecular systematics tools and for monitoring the effects of global change on sub-Antarctic marine ecosystems. After a brief history of scientific campaigns, a list of 166 species was established (103 Rhodophyta, 35 Chlorophyta and 28 Ochrophyta [Phaeophyceae]). Molecular systematics studiess have shown the existence of recurrent discrepancies between the established, morphology-based taxonomy and molecular species delimitation, calling for a revision of systematics. Nevertheless, a first analysis of biogeographical affinities of the marine flora of the Kerguelen Islands is carried out and preliminary results are partially congruent with the main regions currently recognized in the Southern Ocean suggesting the importance of long-distance dispersal to explain the observed distribution patterns.
Programme: 1044
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Monchot Hervé, Houmard Claire, Dionne Marie-Michelle, Desrosiers Pierre M, Gendron Daniel, . (2013). The modus operandi of walrus exploitation during the Palaeoeskimo period at the Tayara site, Arctic Canada
. Anthropozoologica, 48(1), 15–36.
Abstract: Thanks to its high nutritional potential and huge ivory canines, walrus (Odobenus rosmarus) appears to have been a key resource in the subsistence economy of Dorset groups. However present archaeological data are sparse and a more global analysis of its exploitation by the Palaeoeskimos is required. The Tayara site (KbFk-7) in Nunavik (Quebec, Canada) yielded a significant assemblage of walrus bones and many manufactured ivory objects. In addition, Tayara serves as a reference site in Eastern Arctic cultural chronology. A thorough zooarchaeological study has been conducted which includes skeletal profile, the sexing and ageing of walrus bones, and a technological study of the manufactured objects, including a use-wear analysis on lithic tools. This allows the discussion of several aspects of the modus operandi for the exploitation of walrus, from the death of the animal to the processing of the raw material into artefacts. Even if the walrus seems to have been treated with the same processes as other species, some specificities have been noted, particularly in the selection of the different skeletal elements for tool productions and the emblematic value that this animal may have played in consumption and production activities.
Programme: 1080
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Martín E. Timaná, Marc Lebouvier, Germinal Rouhan. (2019). Sagina hookeri Timaná, sp. nov. (Caryophyllaceae), a new endemic species for the flora of Île Amsterdam (French Southern and Antarctic Lands) (Vol. 41).
Abstract: A new endemic species of Sagina L., Sagina hookeri Timaná, sp. nov. (Caryophyllaceae) is described for the flora of Île Amsterdam, in the southern Indian Ocean (French Southern and Antarctic Lands). Differences between this taxon and S. diffusa (Hook.f.) Timaná (endemic to the neighboring island of Saint-Paul) and S. procumbens L. (introduced in several circum-austral islands) are discussed, and an identification key to those three Sagina species occurring in Saint-Paul and Amsterdam islands is presented.
Programme: 136
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Gorodetskaya I V, Kneifel S, Maahn M, Van Tricht K, Schween J H, Crewell S, Van Lipzig N P M, . (2014). Cloud and precipitation properties from ground-based remote sensing instruments in East Antarctica
. The Cryosphere Discuss., 8(4), 4195–4241.
Abstract: A new comprehensive cloud-precipitation-meteorological observatory has been established at Princess Elisabeth base, located in the escarpment zone of Dronning Maud Land, East Antarctica. The observatory consists of a set of ground-based remote sensing instruments (ceilometer, infrared pyrometer and vertically profiling precipitation radar) combined with automatic weather station measurements of near-surface meteorology, radiative fluxes, and snow accumulation. In this paper, the observatory is presented and the potential for studying the evolution of clouds and precipitating systems is illustrated by case studies. It is shown that the synergetic use of the set of instruments allows for distinguishing ice, mixed-phase and precipitating clouds, including some information on their vertical extent. In addition, wind-driven blowing snow events can be distinguished from deeper precipitating systems. Cloud properties largely affect the surface radiative fluxes, with liquid-containing clouds dominating the radiative impact. A statistical analysis of all measurements (in total 14 months mainly occurring in summer/autumn) indicates that these liquid-containing clouds occur during as much as 20% of the cloudy periods. The cloud occurrence shows a strong bimodal distribution with clear sky conditions 51% of the time and complete overcast conditions 35% of the time. Snowfall occurred 17% of the cloudy periods with a predominance of light precipitation and only rare events with snowfall > 1 mm h-1 water equivalent (w.e.). Three of such intensive snowfall events occurred during 2011 contributing to anomalously large annual snow accumulation. This is the first deployment of a precipitation radar in Antarctica allowing to assess the contribution of the snowfall to the local surface mass balance. It is shown that on the one hand large accumulation events (>10 mm w.e. day-1) during the measurement period of 26 months were always associated with snowfall, but that on the other hand snowfall did not always lead to accumulation. In general, this promising set of robust instrumentation allows for improved insight in cloud and precipitation processes in Antarctica and can be easily deployed at other Antarctic stations.
Programme: 411
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Barral H, Genthon C, Trouvilliez A, Brun C, Amory C, . (2014). Blowing snow at D17, Adélie Land, Antarctica: atmospheric moisture issues
. The Cryosphere Discuss., 8(3), 2759–2798.
Abstract: Three years of blowing snow and meteorological observations have been collected along a 7 m mast at site D17 in coastal Adélie Land, Antarctica. This is a region particularly exposed to katabatic winds. The atmospheric surface layer is often close to saturation because of the sublimation of the airborne snow particles. A systematic dry bias results in atmospheric models that ignore blowing snow and its moistening effects, and in meteorological analyses that use such model. The Crocus snow-pack model, including a parameterization for the erosion of surface snow by wind, reproduces the observed march of snow accumulation and ablation if the observed meteorology is used as input. Because of subsaturation, a 2.5 fold increase in surface sublimation is obtained if analyzed surface air meteorology is used. The sublimation obtained in the Crocus model poorly agrees with the moisture fluxes evaluated using the profile method along the mast. Moisture gradients are very weak, particularly when blowing snow saturates the air, to a point where measurement accuracy is an issue. Using the profile method, the measurement uncertainties are strongly amplified in case of strong wind. In such conditions, a single level bulk parameterization with surface energy balance closure as in the Crocus model is preferred. At D17, more than half of the total snow fall is removed by erosion and sublimation, both at the surface and, mainly, of airborne snow particles.
Programme: 411
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E. Le Meur, M. Sacchettini, S. Garambois, E. Berthier, A. S. Drouet, G. Durand, D. Young, J. S. Greenbaum, D. D. Blankenship, J. W. Holt, E. Rignot, J. Mouginot, Y. Gim, D. Kirchner, B. de Fleurian, O. Gagliardini and F. Gillet-Chaulet
. (2013). Two independent methods for mapping the grounding line of an outlet glacier – example from the Astrolabe Glacier, Terre Adélie, Antarctica
. The Cryosphere Discuss., 7(4), 3969–4014.
Abstract: Abstract
The grounding line is a key element acting on the dynamics of coastal outlet glaciers.
Knowing its position accurately is fundamental for both modelling the glacier dynamics
and establishing a benchmark to which one can later refer in case of change. Here we
� �map the grounding line of the Astrolabe Glacier in East Antarctica (66 41 S; 140 05 E),
using hydrostatic and tidal methods. The first method is based on new surface and
ice thickness data from which the line of buoyant flotation is found. We compare this
hydrostatic map with kinematic GPS measurements of the tidal response of the ice
surface. By detecting the transitions where the ice starts to move vertically in response
to the tidal forcing we find control points for the grounding line position along GPS
profiles. With the help of a 2-dimensional elastic plate model, rigid elastic deviations are
computed and applied to these control points. Once the extent of the grounding zone,
the kinematic approach is consistent with the hydrostatic map. These two approaches
lead us to propose a grounding line for the Astrolabe Glacier that significantly deviates
from those obtained so far from satellite imagery.
Programme: 1053
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Picard G, Royer A, Arnaud L, Fily M, . (2013). Influence of meter-scale wind-formed features on the variability of the microwave brightness temperature around Dome C in Antarctica
. The Cryosphere Discuss., 7(4), 3675–3716.
Abstract: Space-borne passive microwave radiometers are widely used to retrieve information in snowy regions by exploiting the high sensitivity of microwave emission to snow properties. For the Antarctic Plateau, many studies presenting retrieval algorithms or numerical simulations have assumed, explicitly or not, that the subpixel-scale heterogeneity is negligible and that the retrieved properties were representative of whole pixels. In this paper, we investigate the spatial variations of brightness temperature over a range of a few kilometers in the Dome C area. Using ground-based radiometers towed by a vehicle allowing measurements with meter resolution, we collected brightness temperature transects at 11, 19 and 37 GHz at horizontal and vertical polarizations. The most remarkable observation was a series of regular undulations of the signal with a significant amplitude of up to 10 K at 37 GHz and a quasi-period of 30–50 m. In contrast, the variability at longer length scales seemed to be weak in the investigated area and the mean brightness temperature was close to AMSR-E and WindSat satellite observations for all the frequencies and polarisations. To establish a link between the snow characteristics and undulation-scale variations of microwave emission, we collected detailed snow grain size and density profiles to run the DMRT-ML microwave emission model at two points where opposite extrema of brightness temperature were observed. The numerical simulations revealed that the difference in density of the upper first meter of the snowpack explained most of the brightness temperature variations. In addition, we found in the field that these variations of density were linked to the hardness of the snowpack. Areas of hard snow – probably formed by the wind – were clearly visible and covered as much as 39% of the investigated area. Their brightness temperature was higher than in normal areas. This result implied that the microwave emission measured by satellites over Dome C is more complex than expected and very likely depends on the areal proportion of the two different types of areas having distinct snow properties.
Programme: 902
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