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Edel, L., J.-f. Rysman, C. Claud, C. Palerme, And C. Genthon. (2019). Potential of Passive Microwave around 183 GHz for Snowfall Detection in the Arctic (Vol. 11). Bachelor's thesis, , .
Abstract: This study evaluates the potential use of the Microwave Humidity Sounder (MHS) for snowfall detection in the Arctic. Using two years of colocated MHS and CloudSat observations, we develop an algorithm that is able to detect up to 90% of the most intense snowfall events (snow water path ≥400 g m−2 and 50% of the weak snowfall rate events (snow water path ≤50 g m−2. The brightness temperatures at 190.3 GHz and 183.3 ± 3 GHz, the integrated water vapor, and the temperature at 2 m are identified as the most important variables for snowfall detection. The algorithm tends to underestimate the snowfall occurrence over Greenland and mountainous areas (by as much as −30%), likely due to the dryness of these areas, and to overestimate the snowfall occurrence over the northern part of the Atlantic (by up to 30%), likely due to the occurrence of mixed phase precipitation. An interpretation of the selection of the variables and their importance provides a better understanding of the snowfall detection algorithm. This work lays the foundation for the development of a snowfall rate quantification algorithm.
Keywords: snowfall; Arctic; passive microwaves; CloudSat; machine learning
Programme: 1013
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Alexander Kokhanovsky, Simon Gascoin, Laurent Arnaud, Ghislain Picard. (2021). Retrieval of Snow Albedo and Total Ozone Column from Single-View MSI/S-2 Spectral Reflectance Measurements over Antarctica (Vol. 13).
Abstract: We proposed a simple algorithm to retrieve the total ozone column and snow properties (spectral albedo and effective light absorption path) using the high spatial resolution single–view MSI/S-2 measurements over Antarctica. In addition, the algorithm allows the retrieval of the snow grain size on a scale of 10–20 m. This algorithm should be useful for the understanding of intra-pixel total ozone and snow albedo variability in complement to satellite observations performed on a much coarser spatial resolution scale (0.3–1 km and even larger spatial scales).
Keywords: albedo inverse problems light scattering radiative transfer snow snow grain size
Programme: 1110
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Jean-Michel Friedt, Éric Bernard, Madeleine Griselin. (2023). Ground-Based Oblique-View Photogrammetry and Sentinel-1 Spaceborne RADAR Reflectivity Snow Melt Processes Assessment on an Arctic Glacier (Vol. 15).
Abstract: The snowpack evolution during the melt season on an Arctic glacier is assessed using ground-based oblique-view cameras, spaceborne imaging and spaceborne RADAR. The repeated and systematic Synthetic Aperture RADAR (SAR) imaging by the European Space Agency’s Sentinel-1 spaceborne RADARs allows for all-weather, all-illumination condition monitoring of the snow-covered fraction of the glacier and hence assessing its water production potential. A comparison of the RADAR reflectivity with optical and multispectral imaging highlights the difference between the observed quantities—water content in the former, albedo in the latter—and the complementarity for understanding the snow melt processes. This work highlights the temporal inertia between the visible spring melting of the snowpack and the snow metamorphism. It was found that the snowpack exhibits that approximately 30 days before it starts to fade.
Keywords: arctic cold region hydrology melting processes Sentinel-1 snowpack properties
Programme: 1108
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Alexander A. Kokhanovsky, Maximillian Brell, Karl Segl, Giovanni Bianchini, Christian Lanconelli, Angelo Lupi, Boyan Petkov, Ghislain Picard, Laurent Arnaud, Robert S. Stone, Sabine Chabrillat. (2023). First Retrievals of Surface and Atmospheric Properties Using EnMAP Measurements over Antarctica (Vol. 15).
Abstract: The paper presents the first retrievals of clean snow properties using spaceborne hyperspectral observations via the Environmental Mapping and Analysis Program (EnMAP). The location close to the Concordia station at the Dome C Plateau (Antarctica) was selected. At this location, the atmospheric effects (except molecular light scattering and absorption) are weak, and the simplified atmospheric correction scheme could be applied. The ice grain size, snow specific surface area, and snow spectral and broadband albedos were retrieved using single-view EnMAP measurements. In addition, we propose a technique to retrieve trace gas concentrations (e.g., water vapor and ozone) from EnMAP observations over the snow surfaces. A close correspondence of satellite and ground-measured parameters was found.
Keywords: ice grain size light scattering radiative transfer snow albedo snow remote sensing
Programme: 1110
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Elodie Da Silva, Emma R. Woolliams, Nicolas Picot, Jean-Christophe Poisson, Henriette Skourup, Geir Moholdt, Sara Fleury, Sajedeh Behnia, Vincent Favier, Laurent Arnaud, Jérémie Aublanc, Valentin Fouqueau, Nicolas Taburet, Julien Renou, Hervé Yesou, Angelica Tarpanelli, Stefania Camici, Renée Mie Fredensborg Hansen, Karina Nielsen, Frédéric Vivier, François Boy, Roger Fjørtoft, Mathilde Cancet, Ramiro Ferrari, Ghislain Picard, Mohammad J. Tourian, Nicolaas Sneeuw, Eric Munesa, Michel Calzas, Adrien Paris, Emmanuel Le Meur, Antoine Rabatel, Guillaume Valladeau, Pascal Bonnefond, Sylvie Labroue, Ole Andersen, Mahmoud El Hajj, Filomena Catapano, Pierre Féménias. (2023). Towards Operational Fiducial Reference Measurement (FRM) Data for the Calibration and Validation of the Sentinel-3 Surface Topography Mission over Inland Waters, Sea Ice, and Land Ice (Vol. 15).
Abstract: The Copernicus Sentinel-3 Surface Topography Mission (STM) Land Altimetry provides valuable surface elevation information over inland waters, sea ice, and land ice, thanks to its synthetic aperture radar (SAR) altimeter and its orbit that covers high-latitude polar regions. To ensure that these measurements are reliable and to maximise the return on investment, adequate validation of the geophysical retrieval methods, processing algorithms, and corrections must be performed using independent observations. The EU-ESA project St3TART (started July 2021) aims to generalise the concept of Fiducial Reference Measurements (FRMs) for the Copernicus Sentinel-3 STM. This work has gathered existing data, made new observations during field campaigns, and ensured that these observations meet the criteria of FRM standards so that they can be used to validate Sentinel-3 STM Land Altimetry products operationally. A roadmap for the operational provision of the FRM, including the definition, consolidation, and identification of the most relevant and cost-effective methods and protocols to be maintained, supported, or implemented, has been developed. The roadmap includes guidelines for SI traceability, definitions of FRM measurement procedures, processing methods, and uncertainty budget estimations.
Keywords: FRM inland water surface height land ice height S3 land STM SAR altimeter sea ice thickness uncertainties
Programme: 411
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Teten'kin A., Smith H.L., Henry A.. (2016). Archaeological evidence for the construction of artificial structures at the Kovrizhka site, Siberia, during the Pleistocene-Holocene transition. . Paleoamerica, .
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Yan Axel Gómez Coutouly. (2022). Questioning the Anthropic Nature of Pedra Furada and the Piauí Sites (Vol. 8).
Abstract: Many archaeologists are still skeptical about a human presence in the Americas during or before the Late Glacial Maximum (LGM), considering that the claim is not yet sustained by hard evidence. Boqueirão da Pedra Furada (Brazil) is one of the most famous pre-LGM claims, but the site has so far been considered ambiguous, and similar concerns have been raised about nearby sites. Nonetheless, for E. Boëda and co-workers, who have been working at these sites, researchers who are still skeptical about the anthropic origin of the assemblages have a psychological barrier and no scientific arguments. Are all skeptics completely blinded by their preconceptions that they cannot see the obvious and unambiguous evidence? To find out, I reviewed the numerous publications of the Piauí sites, and the outcome of my analysis is quite simple: the anthropic nature of the LGM/pre-LGM artifacts of the Piauí sites has not been demonstrated.
Keywords: Brazil geofacts Late Glacial Maximum Pedra Furada Peopling of the Americas
Programme: 1217
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Barbraud Christophe, Delord Karine, Weimerskirch Henri, . (2015). Extreme ecological response of a seabird community to unprecedented sea ice cover.
. Royal Society open science, 2(5), 140456.
Abstract: Climate change has been predicted to reduce Antarctic sea ice but, instead, sea ice surrounding Antarctica has expanded over the past 30 years, albeit with contrasted regional changes. Here we report a recent extreme event in sea ice conditions in East Antarctica and investigate its consequences on a seabird community. In early 2014, the Dumont d'Urville Sea experienced the highest magnitude sea ice cover (76.8%) event on record (1982-2013: range 11.3-65.3%; mean±95% confidence interval: 27.7% (23.1-32.2%)). Catastrophic effects were detected in the breeding output of all sympatric seabird species, with a total failure for two species. These results provide a new view crucial to predictive models of species abundance and distribution as to how extreme sea ice events might impact an entire community of top predators in polar marine ecosystems in a context of expanding sea ice in eastern Antarctica.
Programme: 109
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Dietz Lars, Arango Claudia P, Dömel Jana S, Halanych Kenneth M, Harder Avril M, Held Christoph, Mahon Andrew R, Mayer Christoph, Melzer Roland R, Rouse Greg W, Weis Andrea, Wilson Nerida G, Leese Florian, . (2015). Regional differentiation and extensive hybridization between mitochondrial clades of the Southern Ocean giant sea spider Colossendeis megalonyx.
. Royal Society open science, 2(7), 140424.
Abstract: Assessing the enormous diversity of Southern Ocean benthic species and their evolutionary histories is a central task in the era of global climate change. Based on mitochondrial markers, it was recently suggested that the circumpolar giant sea spider Colossendeis megalonyx comprises a complex of at least six cryptic species with mostly small and non-overlapping distribution ranges. Here, we expand the sampling to include over 500 mitochondrial COI sequences of specimens from around the Antarctic. Using multiple species delimitation approaches, the number of distinct mitochondrial OTUs increased from six to 15-20 with our larger dataset. In contrast to earlier studies, many of these clades show almost circumpolar distributions. Additionally, analysis of the nuclear internal transcribed spacer region for a subset of these specimens showed incongruence between nuclear and mitochondrial results. These mito-nuclear discordances suggest that several of the divergent mitochondrial lineages can hybridize and should not be interpreted as cryptic species. Our results suggest survival of C. megalonyx during Pleistocene glaciations in multiple refugia, some of them probably located on the Antarctic shelf, and emphasize the importance of multi-gene datasets to detect the presence of cryptic species, rather than their inference based on mitochondrial data alone.
Programme: 1124
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Kernaléguen Laëtitia, Cherel Yves, Guinet Christophe, Arnould John PY. (2016). Mating success and body condition not related to foraging specializations in male fur seals. Royal society open science, 3(7), 160143.
Abstract: Individual specialization is widespread among wild populations. While its fitness consequences are central in predicting the ecological and evolutionary trajectories of populations, they remain poorly understood. Long-term individual foraging specializations occur in male Antarctic (Arctocephalus gazella) and Australian (A. pusillus doriferus) fur seals. Strong selective pressure is expected in these highly dimorphic and polygynous species, raising the question of the fitness payoffs associated with different foraging strategies. We investigated the relationship between individual isotopic niche (a proxy of foraging specialization), body size and condition, and an index of reproductive success (harem size) in territorial males. Individuals varied greatly in their skin and fur isotopic values reflecting a range of foraging strategies within the two populations. However, in both species, isotopic niche was not correlated to body size, condition or mating success (R2/ρ < 0.06). Furthermore, no foraging niche was predominant in either species, which would have indicated a substantial long-term fitness benefit of a particular strategy via a higher survival rate. These results suggest that the fitness consequences of a foraging strategy depend not only on the quality of prey and feeding habitat but also on an individual's hunting efficiency and skills.
Programme: 109
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