1928 research outputs found
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An open-source albedo-wand for the measurement of sea ice albedo
Get PDFSurface albedo is defined as the ratio of incident and reflected solar irradiance and describes the ability of a surface to reflect, rather than absorb incident solar shortwave radiation. It is thus a crucial parameter in the climate system, particularly in the polar oceans. Sea ice albedo is a main driver for light transmission into the polar oceans and thus has a high impact on ocean warming, ice melting and marine primary production. During spring and summer, sea ice albedo can exhibit a significant spatial variability caused by meltwater accumulations on the ice. While complex and expensive solutions for albedo measurements are already available, we want to present a simple open-source design that allows for affordable mapping of spatially varying surface albedo on sea ice and beyond. Our solution is based on off-the-shelf components, such as an Arduino microcontroller integrating affordable light sensors, a GPS unit, data recording on memory card and data display into a simple field strengthened unit. We provide example data from two Arctic field deployments showing the capabilities and limitations of this system
On the determination and simulation of seawater freezing point temperature under high pressure
Get PDFAt present, it is believed that the freezing point temperature of seawater is a function of salinity and pressure, and the freezing point is a key parameter in a coupled air-sea-ice system. Generally, empirical formulas or methods are used to calculate the freezing point of seawater. Especially in high-pressure situations, e.g., under a thick ice sheet or ice shelf, the pressure term must be taken into account in the determination of seawater freezing point temperature. This study summarized various methods that have been used to calculate seawater freezing point with high pressure. The methods that were employed in two ocean-ice models were also assessed. We identified the disadvantages of these methods used in these two models and addressed the corresponding uncertainties of the freezing point temperature formulas. This study provides useful information on the calculation of the freezing point temperature in numerical modeling and indicates a need to investigate the sensitivity of numerical simulations to the uncertainties in the freezing point temperature in future
A characteristic study of humic acids isolated from Arctic fjord sediments
Get PDFHumic substances are ubiquitous natural materials found in sediments as a product of biochemical transformation reactions representing a significant proportion of organic carbon cycle on earth. This study involves the analysis of humic substances with special emphasis on humic acids (HAs) in sediments collected from the Kongsfjorden System of Arctic region in June, 2017. The characterization of the isolated HAs were done using various spectroscopic techniques viz. UV-visible, Fluorescence, FTIR and NMR. Isolated HAs were also undergone for elemental analysis along with other characterization. The UV spectral analysis results with a lower E4/E6 ratio suggesting the presence of HAs with high degree of aromaticity and condensation. Indications for the presence of hydroxyl, methyl, methylene, carbonyl, carboxyl, phenol, alcohol and amide groups were obtained from the FTIR spectrums of HAs. NMR spectral characteristics also confirm the presence of OH group as well as the presence of CH protons adjacent to C=X, were X can be any electronegative element. This also confirms the presence of carbonyl group which is also evident in the FTIR spectral studies. Presence of aliphatic regions slightly more dominated with long chain and/or alicyclic moieties rather than methyl groups was also inferred from the results of NMR
Mesozoic and Cenozoic microbiotas from eastern Antarctic Peninsula: adaptation to a changing palaeoenvironment
Get PDFA compiled selected literature on some groups of microfossils of the Mesozoic and Cenozoic of the James Ross Basin, eastern Antarctic Peninsula, is presented here, in order to show how the microbiota has been modified over time, triggered by environmental changes. The analyzed microfossils consist of palynomorphs (mostly pollen grains, spores, and dinoflagellate cysts), foraminifers and bryozoans. Dinoflagellate cysts and pollen-spores have been recorded in Jurassic to Pleistocene sedimentary outcrops. Dinoflagellate cysts proved to be good indicators for productivity and/or nutrient availability, surface water temperature and chemistry, the position of ancient shorelines and paleoceanographic trends. Pollen and spores allowed reconstruction of floral community and thus characterization of the climate that prevailed on the continent. Foraminifera, recovered from the Lower Cretaceous to the Pleistocene sedimentary rocks, provided information about the bathymetry, showing different marine settings (e.g., coastal, inner neritic, outer neritic, upper bathyal) in different localities. The bryozoan record is restricted to the Cenozoic. Their colonial growth-forms reflect several environmental conditions such as shallow waters with a low rate of sedimentation, hard substrate and moderate or strong current action for the analyzed localities. The study of the Antarctic ecosystems based on the fossil microbiota and their response to the climate and the continental configuration changes, allowed understanding of the composition and dynamics of the polar environments, which have an important role in the Earth climate
The fossil record of Antarctic land mammals: commented review and hypotheses for future research
Get PDFThe fossil record of terrestrial mammals in Antarctica is temporally and geographically constrained to the Eocene outcrops of La Meseta and Submeseta formations in Seymour (Marambio) Island in West Antarctica. The faunal assemblage indicates a clear South American imprint since all the groups have a close phylogenetic relationship with Cretaceous and Paleogene mammals from Patagonia. Despite the presence of several mammalian taxonomic groups: Dryolestida, Gondwanatheria, Eutheria and Metatheria, the presence of other major mammalian taxa should be expected and will probably be confirmed by new findings. Placental mammals with an inferred body mass between 10 to 400 kg in size, are represented by xenarthrans, and two groups of the so called South American native ungulates: Astrapotheria and Litopterna. The Metatheria are the smaller (less than 1 kg) and most abundant components of the fauna. Marsupials are represented by derorhynchid ameridelphians, several microbiotherian australidelphians (both microbiotheriids and woodburnodontids), and ?glasbiid prepidolopod and polydolopid polydolopimorphians. Plus, there are remains of several mammalian teeth of indeterminate phylogenetic affinities. The present knowledge of the Southern Hemisphere mammalian evolution and paleogeographic change through time, indicates that Antarctica played a major role for land mammals, at least since the Jurassic. The actual representation of Paleogene terrestrial mammals in Antarctica is most probably biased, as all the evidence indicates that australosphenidan mammals should be present in this continent since the Jurassic
Ecosystem services in the Arctic: a thematic review
Get PDFThe study presents the first systematic review of the existing literature on Arctic ES. Applying the Search,
Appraisal, Synthesis and Analysis (SALSA) and snowballing methods and three selection criteria, 33 publications
were sourced, including peer-reviewed articles, policy papers and scientific reports, and their content synthesised using the thematic analysis method. Five key themes were identified: (1) general discussion of Arctic ES, (2) Arctic social-ecological systems, (3) ES valuation, (4) ES synergies and/or trade-offs, and (5) integrating the ES perspective into management. The meta-synthesis of the literature reveals that the ES concept is increasingly being applied in the Arctic context in all five themes, but there remain large knowledge gaps concerning mapping, assessment, economic valuation, analysis of synergies, trade-offs, and underlying mechanisms, and the social effects of ES changes. Even though ES are discussed in most publications as being relevant for policy, there are few practical examples of its direct application to management. The study concludes that more primary studies of Arctic ES are needed on all of the main themes as well as governance initiatives to move Arctic ES research from theory to practice
Department of Defense Arctic Strategy
Get PDFThe 2019 Department of Defense (DoD) Arctic Strategy updates the previous 2016 DoD Arctic Strategy as requested by Section 1071 of the John S. McCain National Defense Authorization Act for fiscal year (FY) 2019. This update includes a classified anne
EPSC Strategic Notes - Walking on Thin Ice: A Balanced Arctic Strategy for the EU
Get PDFA remote frontier for thousands of years, the Arctic is rapidly gaining international attention.
Global warming is causing the Central Arctic Ocean’s ice to melt at an unprecedented rate, threatening crucial ecosystems and biodiversity in the wider Arctic region.
As a result, global sea levels are rising, with potentially cataclysmic global social, economic and environmental consequences over the long term, irreversible on a timescale relevant to human societies
Country Report 2019: Reports from the Adhering Bodies of the International Permafrost Association
Get PDFEarly Cenozoic diorite and diabase from Doumer Island, Antarctic Peninsula: zircon U-Pb geochronology, petrogenesis and tectonic implications
Get PDFIn order to understand the petrogenesis and tectonic setting of diorite and diabase units on Doumer Island, Antarctic Peninsula, this paper reports new laser ablation—inductively coupled plasma—mass spectrometry (LA-ICP-MS) zircon U-Pb, geochemical, and Lu-Hf isotopic data for the magmatism. The diorite and diabase samples yielded zircon U-Pb ages of 55.4 ± 0.3 and 52.8 ± 0.4 Ma, respectively. These samples are enriched in the large ion lithophile elements and the light rare earth elements, and are depleted in the high field strength elements. The zircons in these samples yield Hf (t) values from 9.03 to 11.87 and model ages (TDM2) of 342–524 Ma. The major, trace, rare earth element (REE), and Hf isotopic data for the diorites indicate that these units were formed by the mixing of magmas generated by (a) the partial melting of mantle wedge material that experienced fluid-metasomatism in a subduction zone setting, and (b) the melting of juvenile crustal material induced by the upwelling of mantle-derived magmas in a subduction–collision setting. The diabase units contain higher total REE concentrations than the diorite, indicating they were derived from a different source region. These samples also have higher Mg# values and contain lower concentrations of Cr and Ni than the diorites, and have weakly negative Nb and Ta anomalies with Nb/Ta values of <3. The zircons in these samples yield Hf (t) values from 9.08 to 11.11 and model ages (TDM2) of 389– 503 Ma. The major, trace, REE, and Hf isotopic compositions of the diabase units indicate that that they were derived from the mixing of depleted mantle-derived magmas with magmas generated by the melting of juvenile crustal material which was induced by the upwelling of the mantle into the crust. Overall the Cenozoic diorite and diabase on Doumer Island is related to subduction environment