Search results for " Planetary"
showing 10 items of 5408 documents
Millennial-scale climate variability during the last 12.5 ka recorded in a Caribbean speleothem
2013
Abstract We present a speleothem stable oxygen isotope record for the last 12.5 ka based on two stalagmites from western Cuba. The δ18O signal is interpreted to represent past precipitation variability. Both stalagmites show a pronounced transition from higher δ18O values (indicating drier conditions) to more negative δ18O values (suggesting wetter conditions) between 10 and 6 ka. This transition is also visible in a planktonic δ18O record off Haiti. On orbital timescales, the δ18O value of Caribbean precipitation, thus, strongly resembles the oxygen isotope composition of Caribbean surface water. On millenial timescales, the speleothem δ18O record shows a high correlation to a North Atlant…
Ice age at the Middle–Late Jurassic transition?
2003
A detailed record of sea surface temperatures in the Northern Hemisphere based on migration of marine invertebrate fauna (ammonites) and isotopic thermometry (δ18O values of shark tooth enamel) indicates a severe cooling at the Middle–Late Jurassic transition (MLJT), about 160 Ma ago. The magnitude of refrigeration (1–3°C for lower middle latitudes) and its coincidence in time with an abrupt global-scale fall of sea level documented through sequence stratigraphy are both suggestive of continental ice formation at this time. Ice sheets may have developed over the high-latitude mountainous regions of Far-East Russia. The drastic cooling just post-dated the Middle–Late Callovian widespread dep…
A Methodology for Comparing the Surface Urban Heat Island in Selected Urban Agglomerations Around the World from Sentinel-3 SLSTR Data
2020
[EN] Retrieval of land surface temperature (LST) from satellite data allows to estimate the surface urban heat island (SUHI) as the difference between the LST obtained in the urban area and the LST of its surroundings. However, this definition depends on the selection of the urban and surroundings references, which translates into greater difficulty in comparing SUHI values in different urban agglomerations across the world. In order to avoid this problem, a methodology is proposed that allows reliable quantification of the SUHI. The urban reference is obtained from the European Space Agency Climate Change Initiative Land Cover and three surroundings references are considered; that is, the …
Experimental deformation of deuterated ice in 3D and 2D: identification of grain-scale processes
2015
Major polar ice sheets and ice caps experience cycles of variable flow during different glacial periods and as a response to past warming. The rate and localisation of deformation inside an ice body controls the evolution of ice microstructure and crystallographic fabric. This is critical for interpreting proxy signals for climate change, with deformation overprinting and disrupting stratigraphy deep under ice caps due to the nature of the flow. The final crystallographic fabric in polar ice sheets provides a record of deformation history, which in turn controls the flow properties of ice during further deformation and affects geophysical sensing of ice sheets. For example, identification o…
New perspectives on the evolution of the genus Typhlatya (Crustacea, Decapoda): first record of a cavernicolous atyid in the Iberian Peninsula, Typhl…
1995
On several occasions, shrimps belonging to a new species of the genus Typhlatya were collected in a cave in the province of Castellón, Spain. This is the first record of the genus in the Iberian Peninsula. The species is described and the validity, distribution, and zoogeography of the genus, as well as the status of the genus Spelaeocaris, are discussed. Former models for the evolution of the genus Typhlatya and its genus group are reviewed, as well as the system of inner classification of the Atyidae and its biogeographical meaning. For the age and evolution of the genus we developed a new model based on vicariance principles that involves further evolution of each species after the disru…
Isopoda Asellota de Turquie récoltés en 1987
1996
Asellus aquaticus is present in 19 of about 100 Turkish groundwater stations prospected during biospeleological explorations. All specimens of these stygophilic populations remain oculate, even though their integumental pigmentation is more or less reduced. Proasellus lykaonicus Argano & Pesce, 1978 has been found again in a second cave, nearby the type locality. A large and endemic, stygobiont species, Proasellus pisidicus n. sp., from phreatic groundwater, Vilâyet Burdur, and the minute Proasellus pamphylicus n. sp. from interstitial waters of the eastern part of Vilâyet Antalya are described. The stygobiont proasellids of Asia Minor, P. lykaonicus and P. pisidicus n. sp. belong to the sa…
Analysis of the Rockfall Phenomena Contributing to the Evolution of a Pocket Beach Area Using Traditional and Remotely Acquired Data (Lo Zingaro Natu…
2023
The coastal domain of central western Sicily is characterized by the presence of rocky coasts, which mainly consist of pocket beaches situated between bedrock headlands that constitute ecological niches of great touristic and economic value. In this peculiar morphodynamic system, the sedimentary contributions are mainly derived from the rockfall that affects the back of nearby cliffs or the sediment supply of small streams that flow into it. In this study, we investigated the geomorphological processes and related landforms that contribute to the evolution of a pocket beach area located in a coastal sector of NW Sicily Island. The cliffs in this are affected by several rockfalls, and deposi…
OGLE-2008-BLG-510: first automated real-time detection of a weak microlensing anomaly - brown dwarf or stellar binary?
2012
The microlensing event OGLE-2008-BLG-510 is characterized by an evident asymmetric shape of the peak, promptly detected by the Automated Robotic Terrestrial Exoplanet Microlensing Search (ARTEMiS) system in real time. The skewness of the light curve appears to be compatible both with binary-lens and binary-source models, including the possibility that the lens system consists of an M dwarf orbited by a brown dwarf. The detection of this microlensing anomaly and our analysis demonstrate that: (1) automated real-time detection of weak microlensing anomalies with immediate feedback is feasible, efficient and sensitive, (2) rather common weak features intrinsically come with ambiguities that ar…
Statistical upscaling of ecosystem CO2 fluxes across the terrestrial tundra and boreal domain: Regional patterns and uncertainties
2021
The regional variability in tundra and boreal carbon dioxide (CO2) fluxes can be high, complicating efforts to quantify sink-source patterns across the entire region. Statistical models are increasingly used to predict (i.e., upscale) CO2 fluxes across large spatial domains, but the reliability of different modeling techniques, each with different specifications and assumptions, has not been assessed in detail. Here, we compile eddy covariance and chamber measurements of annual and growing season CO2 fluxes of gross primary productivity (GPP), ecosystem respiration (ER), and net ecosystem exchange (NEE) during 1990–2015 from 148 terrestrial high-latitude (i.e., tundra and boreal) sites to a…
What is important in history teaching? Student class teachers’ conceptions
2020
In Finland, history is taught in comprehensive schools at both primary and secondary levels. In primary schools, teachers are qualified class teachers who study one or two history courses during their teacher education. The amount of history taught in teacher education is limited, but student class teachers have studied history while at comprehensive school and general upper secondary school, and they have lived experience of historical cultures as members of different groups and communities. Thus, they have conceptions of what history teaching in school is, and what it should be. In this article, student class teachers’ conceptions of teaching history were examined using data (n=92) consi…