Unnikrishnan A. S., A. Matthews, M. Gravelle, L. Testut, T. Aarup, P. L. Woodworth and B. A. Kumar. (2019). Tide gauges. In: Beal, Lisa M.; Vialard, Jérôme; Roxy, Mathew K., (eds.) Full Report. IndOOS-2: A roadmap to sustained observations of the Indian Ocean for 2020-2030.
Abstract: Tide gauge measurements provide data for routine tidal predictions in ports as well as for extreme events such as storm surges and tsunamis. Along with satellite altimeter measurements, tide gauges also provide measurements used for sea-level rise estimates. This is particularly important for impact assessment in low-lying coastlines of south Asia as well as islands such as the Maldives in the Indian Ocean.
Programme: 688
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Denis Mercier, Dominique Laffly. (2003). La progradation des littoraux meubles au Spitsberg : une réponse sédimentaire paraglaciaire au réchauffement climatique contemporain (Shorelines progradation in Spitsbergen : a paraglacial sedimentological respons to contemporary climatic change) (Vol. 80).
Abstract: Résumé. – Les milieux polaires comme le Spitsberg répondent avec une grande acuité aux changements climatiques comme celui que nous connaissons depuis la fin du Petit Age glaciaire. Le retrait glaciaire s'accompagne d'un accroissement de la dynamique d'écoulement remobilisant les stocks sédimentaires glaciaires hérités. En aval, à la périphérie des sandurs, les littoraux meubles enregistrent une progradation dans les secteurs actifs et une érosion dans les secteurs ayant perdu les apports fluvio-glaciaires. Cette manifestation géomorphologique illustre la nouvelle dynamique paraglaciaire des paysages du Spitsberg.
Programme: 400
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Papierok B., Dedryver C.-A., Hullé M.. (2016). First records of aphid-pathogenic Entomophthorales in the sub-Antarctic archipelagos of Crozet and Kerguelen. Polar research, 35.
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Patrick Pomerleau, Alain Royer, Alexandre Langlois, Patrick Cliche, Bruno Courtemanche, Jean-Benoît Madore, Ghislain Picard, Éric Lefebvre. (2020). Low Cost and Compact FMCW 24 GHz Radar Applications for Snowpack and Ice Thickness Measurements (Vol. 20).
Abstract: Monitoring the evolution of snow on the ground and lake ice—two of the most important components of the changing northern environment—is essential. In this paper, we describe a lightweight, compact and autonomous 24 GHz frequency-modulated continuous-wave (FMCW) radar system for freshwater ice thickness and snow mass (snow water equivalent, SWE) measurements. Although FMCW radars have a long-established history, the novelty of this research lies in that we take advantage the availability of a new generation of low cost and low power requirement units that facilitates the monitoring of snow and ice at remote locations. Test performance (accuracy and limitations) is presented for five different applications, all using an automatic operating mode with improved signal processing: (1) In situ lake ice thickness measurements giving 2 cm accuracy up to ≈1 m ice thickness and a radar resolution of 4 cm; (2) remotely piloted aircraft-based lake ice thickness from low-altitude flight at 5 m; (3) in situ dry SWE measurements based on known snow depth, giving 13% accuracy (RMSE 20%) over boreal forest, subarctic taiga and Arctic tundra, with a measurement capability of up to 3 m in snowpack thickness; (4) continuous monitoring of surface snow density under particular Antarctic conditions; (5) continuous SWE monitoring through the winter with a synchronized and collocated snow depth sensor (ultrasonic or LiDAR sensor), giving 13.5% bias and 25 mm root mean square difference (RMSD) (10%) for dry snow. The need for detection processing for wet snow, which strongly absorbs radar signals, is discussed. An appendix provides 24 GHz simulated effective refractive index and penetration depth as a function of a wide range of density, temperature and wetness for ice and snow.
Keywords: Antarctica Arctic snow tundra Frequency-Modulated Continuous-Wave (FMCW) radar lake ice thickness snow boreal forest snow density snow monitoring snow water equivalent snow wetness subarctic snow taiga
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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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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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 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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Éric Bernard, Jean-Michel Friedt, Madeleine Griselin. (2021). Snowcover Survey over an Arctic Glacier Forefield: Contribution of Photogrammetry to Identify “Icing” Variability and Processes (Vol. 13).
Abstract: The global climate shift currently underway has significant impacts on both the quality and quantity of snow precipitation. This directly influences the spatial variability of the snowpack as well as cumulative snow height. Contemporary glacier retreat reorganizes periglacial morphology: while the glacier area decreases, the moraine area increases. The latter is becoming a new water storage potential that is almost as important as the glacier itself, but with considerably more complex topography. Hence, this work fills one of the missing variables of the hydrological budget equation of an arctic glacier basin by providing an estimate of the snow water equivalent (SWE) of the moraine contribution. Such a result is achieved by investigating Structure from Motion (SfM) image processing that is applied to pictures collected from an Unmanned Aerial Vehicle (UAV) as a method for producing snow depth maps over the proglacial moraine area. Several UAV campaigns were carried out on a small glacial basin in Spitsbergen (Arctic): the measurements were made at the maximum snow accumulation season (late April), while the reference topography maps were acquired at the end of the hydrological year (late September) when the moraine is mostly free of snow. The snow depth is determined from Digital Surface Model (DSM) subtraction. Utilizing dedicated and natural ground control points for relative positioning of the DSMs, the relative DSM georeferencing with sub-meter accuracy removes the main source of uncertainty when assessing snow depth. For areas where snow is deposited on bare rock surfaces, the correlation between avalanche probe in-situ snow depth measurements and DSM differences is excellent. Differences in ice covered areas between the two measurement techniques are attributed to the different quantities measured: while the former only measures snow accumulation, the latter includes all of the ice accumulation during winter through which the probe cannot penetrate, in addition to the snow cover. When such inconsistencies are observed, icing thicknesses are the source of the discrepancy that is observed between avalanche probe snow cover depth measurements and differences of DSMs.
Keywords: arctic cryosphere moraine photogrammetry snow water equivalent snowcover spatial dynamics UAV-SfM
Programme: 1108
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Rajesh Janardanan, Shamil Maksyutov, Aki Tsuruta, Fenjuan Wang, Yogesh K. Tiwari, Vinu Valsala, Akihiko Ito, Yukio Yoshida, Johannes W. Kaiser, Greet Janssens-Maenhout, Mikhail Arshinov, Motoki Sasakawa, Yasunori Tohjima, Douglas E. J. Worthy, Edward J. Dlugokencky, Michel Ramonet, Jgor Arduini, Jost V. Lavric, Salvatore Piacentino, Paul B. Krummel, Ray L. Langenfelds, Ivan Mammarella, Tsuneo Matsunaga. (2020). Country-Scale Analysis of Methane Emissions with a High-Resolution Inverse Model Using GOSAT and Surface Observations (Vol. 12).
Abstract: We employed a global high-resolution inverse model to optimize the CH4 emission using Greenhouse gas Observing Satellite (GOSAT) and surface observation data for a period from 2011–2017 for the two main source categories of anthropogenic and natural emissions. We used the Emission Database for Global Atmospheric Research (EDGAR v4.3.2) for anthropogenic methane emission and scaled them by country to match the national inventories reported to the United Nations Framework Convention on Climate Change (UNFCCC). Wetland and soil sink prior fluxes were simulated using the Vegetation Integrative Simulator of Trace gases (VISIT) model. Biomass burning prior fluxes were provided by the Global Fire Assimilation System (GFAS). We estimated a global total anthropogenic and natural methane emissions of 340.9 Tg CH4 yr−1 and 232.5 Tg CH4 yr−1, respectively. Country-scale analysis of the estimated anthropogenic emissions showed that all the top-emitting countries showed differences with their respective inventories to be within the uncertainty range of the inventories, confirming that the posterior anthropogenic emissions did not deviate from nationally reported values. Large countries, such as China, Russia, and the United States, had the mean estimated emission of 45.7 ± 8.6, 31.9 ± 7.8, and 29.8 ± 7.8 Tg CH4 yr−1, respectively. For natural wetland emissions, we estimated large emissions for Brazil (39.8 ± 12.4 Tg CH4 yr−1), the United States (25.9 ± 8.3 Tg CH4 yr−1), Russia (13.2 ± 9.3 Tg CH4 yr−1), India (12.3 ± 6.4 Tg CH4 yr−1), and Canada (12.2 ± 5.1 Tg CH4 yr−1). In both emission categories, the major emitting countries all had the model corrections to emissions within the uncertainty range of inventories. The advantages of the approach used in this study were: (1) use of high-resolution transport, useful for simulations near emission hotspots, (2) prior anthropogenic emissions adjusted to the UNFCCC reports, (3) combining surface and satellite observations, which improves the estimation of both natural and anthropogenic methane emissions over spatial scale of countries.
Keywords: anthropogenic GOSAT inverse model methane emission UNFCCC wetland
Programme: 416
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