Search results for "Clima"
showing 10 items of 6069 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…
Effects of the 6th September 2002 earthquake: damage amplification in the south-eastern sector of Palermo explained by GIS technology
2009
During the 6th September 2002 earthquake the highest damage level in Palermo was observed in the SE sector. This is a recent urbanization area where reinforced concrete structures predominate. A detailed analysis of soil properties in Palermo was carried out by City-GIS to investigate a possible role of nearsurface geology on earthquake effects. City-GIS is a tool dedicated to natural hazard evaluation in urban areas. The availability of high density of well log data (stratigraphic and geotechnical) allowed a realistic modeling of surface geology and physical-mechanical properties that control the seismic response. In wide zones of the above mentioned sector of…
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…
Evaporite karst in Italy: A review
2017
none 16 si Although outcropping rarely in Italy, evaporite (gypsum and anhydrite) karst has been described in detail since the early 20th century. Gypsum caves are now known from almost all Italian regions, but are mainly localised along the northern border of the Apennine chain (Emilia Romagna and Marche), Calabria, and Sicily, where the major outcrops occur. Recently, important caves have also been discovered in the underground gypsum mines in Piedmont. During the late 80s and 90s several multidisciplinary studies were carried out in many gypsum areas, resulting in a comprehensive overview, promoting further research in these special karst regions. More recent and detailed studies focused…
G-CLASS: geosynchronous radar for water cycle science – orbit selection and system design
2019
The mission geosynchronous – continental land atmosphere sensing system (G-CLASS) is designed to study thediurnal water cycle, using geosynchronous radar. Although the water cycle is vital to human society, processes on timescalesless than a day are very poorly observed from space. G-CLASS, using C-band geosynchronous radar, could transform this. Itsscience objectives address intense storms and high resolution weather prediction, and significant diurnal processes such assnow melt and soil moisture change, with societal impacts including agriculture, water resource management, flooding, andlandslides. Secondary objectives relate to ground motion observations for earthquake, volcano, and subs…
L'Arctique en mutation
2016
International audience; AVANT-PROPOS..........................................Daniel JOLYCHAPITRE 1 - Fluctuations climatiques récentes en Arctique : l’exemple du Spitsberg occidental, Madeleine GRISELIN, Christelle MARLIN et Jean-Michel FRIEDTCHAPITRE II - Évolution contemporaine des glaciers arctiques ; exemple de l’Austre Lovénbreen (79°N), Eric BERNARD et Florian TOLLECHAPITRE III - Géomorphologie des côtes rocheuses arctiques, SAMUEL ETIENNE, Jim HANSOM et Donald L. FORBESCHAPITRE IV - L’Arctique face aux crises géomorphologiques paraglaciaires, Denis MERCIERCHAPITRE V - Distribution multi-scalaire de la végétation en Arctique, Martha RAYNOLDCHAPITRE VI - Distribution de la végétation …
Globālo klimata pārmaiņu novēršanas politikas izvērtējums
2020
Bakalaura darba temats ir “Globālo klimata pārmaiņu novēršanas politikas izvērtējums”. Globālo klimata pārmaiņu jautājums pēdējo gadu laikā ir atzīts par vienu no steidzamāk risināmajām pasaules problēmām. Darba teorētisko ietvaru veido ieviešanas teorijas un dažādu ieviešanas aspektu teorijas, kā arī teorija par klimata pārmaiņu politiku. Darba empīriskajā daļā, izmantojot teorētiskajā daļā izvirzītos kritērijus, tiek analizēti septiņi Latvijas Republikas Nacionālie ziņojumi ANO Vispārējās konvencijas par klimata pārmaiņām ietvaros. Darba mērķis ir izvērtēt konvencijas saistību īstenošanas laikā veiktos klimata politikas pasākumus un to atbilstību konvencijas mērķim. Atslēgvārdi : globālās…
Transitions in European land-management regimes between 1800 and 2010
2015
Land use is a cornerstone of human civilization, but also intrinsically linked to many global sustainability challenges—from climate change to food security to the ongoing biodiversity crisis. Understanding the underlying technological, institutional and economic drivers of land-use change, and how they play out in different environmental, socio-economic and cultural contexts, is therefore important for identifying effective policies to successfully address these challenges. In this regard, much can be learned from studying long-term land-use change. We examined the evolution of European land management over the past 200 years with the aim of identifying (1) key episodes of changes in land …