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Palerme Cyril, Genthon Christophe, Claud Chantal, Kay Jennifer E, Wood Norman B, LEcuyer Tristan, . (2017). Evaluation of current and projected Antarctic precipitation in CMIP5 models (Vol. 48).
Abstract: On average, the models in the Fifth Climate Model Intercomparison Project archive predict an increase in Antarctic precipitation from 5.5 to 24.5 % between 1986–2005 and 2080–2099, depending on greenhouse gas emissions scenarios. This translates into a moderation of future sea level rise ranging from −19 to −71 mm between 2006 and 2099. However, comparison with CloudSat and ERA-Interim data show that almost all the models overestimate current Antarctic precipitation, some by more than 100 %. If only the models that agree with CloudSat data within 20 % of error are considered, larger precipitation changes (from 7.4 to 29.3 %) and impact on sea level (from −25 to −85 mm) are predicted. A common practice of averaging all models to evaluate climate projections thus leads to a significant underestimation of the contribution of Antarctic precipitation to future sea level. Models simulate, on average, a 7.4 %/°C precipitation change with surface temperature warming. The models in better agreement with CloudSat observations for Antarctic snowfall predict, on average, larger temperature and Antarctic sea ice cover changes, which could explain the larger changes in Antarctic precipitation simulated by these models. The agreement between the models, CloudSat data and ERA-Interim is generally less in the interior of Antarctica than at the peripheries, but the interior is also where climate change will induce the smallest absolute change in precipitation. About three-quarters of the impact on sea level will result from precipitation change over the half most peripheral and lowest elevation part of the surface of Antarctica.
Programme: 1013
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Arisitidi, E., J. vernin, F.-X. Schmider, T. Travouillon, C. Pouzenc, O. traullé, C. Genthon, A. Agabi, E. Bondoux, Z. Chalita, and D. Mearnia. (2015). Monitoring the optical turbulence in the surface layer at Dome C, Antarctica, with sonic anemometers. Monthly Notices of the Royal Astronomical Society, 454, 4304–4315.
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Rysman, J.F., S. Verrier, A. Lahellec, and C. Genthon. (2015). Analysis of boundary layer statistical properties at Dome C, Antarctica. 0006-8314, 156, 145–155.
Abstract: The atmospheric boundary layer over the Antarctic Plateau is unique on account of its isolated location and extreme stability. Here we investigate the characteristics of the boundary layer using wind and temperature measurements from a 45-m high tower located at Dome C. First, spectral analysis reveals that both fields have a scaling behaviour from 30 min to 10 days (spectral slope β≈2β≈2\beta \approx 2). Wind and temperature time series also show a multifractal behaviour. Therefore, it is possible to fit the moment-scaling function to the universal multifractal model and obtain multifractal parameters for temperature (α≈1.51,C1≈0.14α≈1.51,C1≈0.14\alpha \approx 1.51,\, C1\approx 0.14) and wind speed (α≈1.34,C1≈0.13α≈1.34,C1≈0.13\alpha \approx 1.34, \, C1\approx 0.13). The same analysis is repeated separately in winter and summer at six different heights. The ββ\beta parameter shows a strong stratification with height especially in summer, implying that properties of turbulence change surprisingly rapidly from the ground to the top of the tower.
Programme: 1013
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Amory, C., A. Trouvilliez, H. Gallée, F. Naaim-Bouvet, C. Genthon, V. favier, C. Agosta, L. Piard, and H. bellot. (2015). Comparison of aeolian snow transport events and snow mass fluxes between observations and simulations made by the regional climate model MAR in Adélie Land, East Antarctica. TC, 9, 1373–1383.
Abstract: Using the original setup described in Gallée et al. (2013), the MAR regional climate model including a coupled snowpack/aeolian snow transport parameterization, was run at a fine spatial (5 km horizontal and 2 m vertical) resolution over 1 summer month in coastal Adélie Land. Different types of feedback were taken into account in MAR including drag partitioning caused by surface roughness elements. Model outputs are compared with observations made at two coastal locations, D17 and D47, situated respectively 10 and 100 km inland. Wind speed was correctly simulated with positive values of the Nash test (0.60 for D17 and 0.37 for D47) but wind velocities above 10 m s−1 were underestimated at both D17 and D47; at D47, the model consistently underestimated wind velocity by 2 m s−1. Aeolian snow transport events were correctly reproduced with the right timing and a good temporal resolution at both locations except when the maximum particle height was less than 1 m. The threshold friction velocity, evaluated only at D17 for a 7-day period without snowfall, was overestimated. The simulated aeolian snow mass fluxes between 0 and 2 m at D47 displayed the same variations but were underestimated compared to the second-generation FlowCaptTM values, as was the simulated relative humidity at 2 m above the surface. As a result, MAR underestimated the total aeolian horizontal snow transport for the first 2 m above the ground by a factor of 10 compared to estimations by the second-generation FlowCaptTM. The simulation was significantly improved at D47 if a 1-order decrease in the magnitude of z0 was accounted for, but agreement with observations was reduced at D17. Our results suggest that z0 may vary regionally depending on snowpack properties, which are involved in different types of feedback between aeolian transport of snow and z0.
Programme: 1013
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Gallée, H., S. Preunkert, S. Argentini, M. M. Frey, C. Genthon, B. Jourdain, I. Pietroni, G. Casasanta, H. Barral, E. Vignon, and M. Legrand. (2015). Characterization of the boundary layer at Dome C (East Antarctica) during the OPALE summer campaign. Atmos. Chem. Phys., 15, 6225–6236.
Abstract: Regional climate model MAR (Modèle Atmosphérique Régional) was run for the region of Dome C located on the East Antarctic plateau, during Antarctic summer 2011–2012, in order to refine our understanding of meteorological conditions during the OPALE tropospheric chemistry campaign. A very high vertical resolution is set up in the lower troposphere, with a grid spacing of roughly 2 m. Model output is compared with temperatures and winds observed near the surface and from a 45 m high tower as well as sodar and radiation data. MAR is generally in very good agreement with the observations, but sometimes underestimates cloud formation, leading to an underestimation of the simulated downward long-wave radiation. Absorbed short-wave radiation may also be slightly overestimated due to an underestimation of the snow albedo, and this influences the surface energy budget and atmospheric turbulence. Nevertheless, the model provides sufficiently reliable information about surface turbulent fluxes, vertical profiles of vertical diffusion coefficients and boundary layer height when discussing the representativeness of chemical measurements made nearby the ground surface during field campaigns conducted at Concordia station located at Dome C (3233 m above sea level).
Programme: 1013
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Vacquié-Garcia Jade, Guinet Christophe, Dragon Anne-Cécile, Viviant Morgane, El Ksabi Nory, Bailleul Frédéric. (2015). Predicting prey capture rates of southern elephant seals from track and dive parameters. Mar. Ecol. Prog. Ser., 541.
Abstract: In the marine environment, track and dive parameter data (obtained using Argos or GPS tags and time?depth recorders) are commonly used to provide proxies for foraging behaviour of marine predators. However, their accuracy is rarely assessed. Recently, the addition of head-mounted accelerometers has allowed for detection of prey capture attempts (PCAs) at sea, allowing for more accurate estimations of foraging behaviour. Despite increased numbers of such devices being deployed, their use is still marginal compared with other tools which measure track and dive parameters. The objectives of our study were (1) to identify the most relevant combination of tracking and diving metrics in predicting the frequency of PCAs in female southern elephant seals Mirounga leonina from the Kerguelen Islands, and (2) to apply it to a broader range of individuals for which only tracking and diving data were available. The results of our models were consistent with the optimal foraging theory as well as the optimal diving theory. The model with the best predictive performance was the one that combined both tracking and diving information. However, most of the variability in the number of PCAs could be solely explained by changes in the diving behaviour of seals. Finally, we used the best predictive model on 20 individuals, which had not been fitted with accelerometers, to determine their main foraging zones. The behavioural indicators established in this study constitute a useful ecological tool for population monitoring and conservation purposes.
Programme: 109
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Vacquié-Garcia Jade, Guinet Christophe, Laurent Cécile, Bailleul Frédéric. (2015). Delineation of the southern elephant seal's main foraging environments defined by temperature and light conditions. Deep Sea Research Part II: Topical Studies in Oceanography, 113, 145–153.
Abstract: Abstract Changes in marine environments, induced by the global warming, are likely to influence the prey field distribution and consequently the foraging behaviour and the distribution of top marine predators. Thanks to bio-logging, the simultaneous measurements of fine-scale foraging behaviors and oceanographic parameters by predators allow characterizing their foraging environments and provide insights into their prey distribution. In this context, we propose to delimit and to characterize the foraging environments of a marine predator, the Southern Elephant Seal (SES). To do so, the relationship between oceanographic factors and prey encounter events (PEE) was investigated in 12 females SES from Kerguelen Island simultaneously equipped with accelerometers and with a range of physical sensors (temperature, light and depth). PEEs were assessed from the accelerometer data at high spatio-temporal precision while the physical sensors allowed the continuous monitoring of environmental conditions encountered by the SES when diving. First, visited and foraging environments were distinguished according to the oceanographic conditions encountered in the absence and in presence of PEE. Then, a hierarchical classification of the physical parameters recorded during PEEs led to the distinction of five different foraging environments. These foraging environments were structured according to the main frontal systems of the SO. One was located north to the subantarctic front (SAF) and characterized by high temperature and depth, and low light levels. Another, characterized by intermediate levels of temperature, light and depth, was located between the SAF and the polar front (PF). And finally, the last three environments were all found south to the PF and, characterized by low temperature but highly variable depth and light levels. The large physical and/or spatial differences found between these environments suggest that, depending on the location, different prey communities are targeted by SES over a broad range of water temperature, light level and depth conditions. This result highlights the versatility of this marine predator. In addition, in most cases, PEEs were found deeper during the day than during the night, which is indicative of mesopelagic prey performing nycthemeral migration, a behaviour consistent with myctophids species thought to represent the bulk of Kerguelen SES female diets.
Programme: 109
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Southwell Colin, Emmerson Louise, McKinlay John, Newbery Kym, Takahashi Akinori, Kato Akiko, Barbraud Christophe, DeLord Karine, Weimerskirch Henri. (2015). Spatially Extensive Standardized Surveys Reveal Widespread, Multi-Decadal Increase in East Antarctic Adélie Penguin Populations. PLOS ONE, 10(10).
Abstract: Seabirds are considered to be useful and practical indicators of the state of marine ecosystems because they integrate across changes in the lower trophic levels and the physical environment. Signals from this key group of species can indicate broad scale impacts or response to environmental change. Recent studies of penguin populations, the most commonly abundant Antarctic seabirds in the west Antarctic Peninsula and western Ross Sea, have demonstrated that physical changes in Antarctic marine environments have profound effects on biota at high trophic levels. Large populations of the circumpolar-breeding Adélie penguin occur in East Antarctica, but direct, standardized population data across much of this vast coastline have been more limited than in other Antarctic regions. We combine extensive new population survey data, new population estimation methods, and re-interpreted historical survey data to assess decadal-scale change in East Antarctic Adélie penguin breeding populations. We show that, in contrast to the west Antarctic Peninsula and western Ross Sea where breeding populations have decreased or shown variable trends over the last 30 years, East Antarctic regional populations have almost doubled in abundance since the 1980’s and have been increasing since the earliest counts in the 1960’s. The population changes are associated with five-year lagged changes in the physical environment, suggesting that the changing environment impacts primarily on the pre-breeding age classes. East Antarctic marine ecosystems have been subject to a number of changes over the last 50 years which may have influenced Adélie penguin population growth, including decadal-scale climate variation, an inferred mid-20th century sea-ice contraction, and early-to-mid 20th century exploitation of fish and whale populations.
Programme: 109
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Jenouvrier Stephanie, Peron Clara, Weimerskirch Henri, . (2015). Ice-Dependent Southern Fulmar. Bulletin of the Ecological Society of America, 96(4), 664–666.
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Heerah Karine, Hindell Mark, Guinet Christophe, Charrassin Jean?Benoît. (2015). From high-resolution to low-resolution dive datasets: a new index to quantify the foraging effort of marine predators. Animal Biotelemetry, 3, 42.
Abstract: In the last decade, thousands of satellite-relayed data loggers (SRDLs) have been deployed, providing large datasets on marine predator movement patterns at sea and their diving behaviour. However, the latter is in a highly summarised, low-resolution form, from which it is difficult to make the sorts of important behavioural inferences that are possible from higher-resolution datasets (such as detection of likely foraging events). The main objective of this study was to develop a simple, but accurate tool to detect and quantify within-dive foraging periods in low-resolution dives.
Programme: 109
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