Climate change impacts on wildfires in a Mediterranean environment     

Marco Turco  Maria-Carmen Llasat  Jost von Hardenberg  Antonello Provenzale 《Climatic change》2014,125(3-4):369-380

We analyse the observed climate-driven changes in summer wildfires and their future evolution in a typical Mediterranean environment (NE Spain). By analysing observed climate and fire data from 1970 to 2007, we estimate the response of fire number (NF) and burned area (BA) to climate trends, disentangling the drivers responsible for long-term and interannual changes by means of a parsimonious Multi Linear Regression model (MLR). In the last forty years, the observed NF trend was negative. Here we show that, if improvements in fire management were not taken into account, the warming climate forcing alone would have led to a positive trend in NF. On the other hand, for BA, higher fuel flammability is counterbalanced by the indirect climate effects on fuel structure (i.e. less favourable conditions for fine-fuel availability and fuel connectivity), leading to a slightly negative trend. Driving the fire model with A1B climate change scenarios based on a set of Regional Climate Models from the ENSEMBLES project indicates that increasing temperatures promote a positive trend in NF if no further improvements in fire management are introduced.  相似文献   

Impacts of the use of the geological subsurface for energy storage: an investigation concept     

Sebastian Bauer  Christof Beyer  Frank Dethlefsen  Peter Dietrich  Rainer Duttmann  Markus Ebert  Volker Feeser  Uwe Görke  Ralf Köber  Olaf Kolditz  Wolfgang Rabbel  Tom Schanz  Dirk Schäfer  Hilke Würdemann  Andreas Dahmke 《Environmental Earth Sciences》2013,70(8):3935-3943

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Multitemporal ALSM change detection,sediment delivery,and process mapping at an active earthflow   总被引：1，自引：0，他引：1  

Stephen B. DeLong  Carol S. Prentice  George E. Hilley  Yael Ebert 《地球表面变化过程与地形》2012,37(3):262-272

Remote mapping and measurement of surface processes at high spatial resolution is among the frontiers in Earth surface process research. Remote measurements that allow meter‐scale mapping of landforms and quantification of landscape change can revolutionize the study of landscape evolution on human timescales. At Mill Gulch in northern California, USA, an active earthflow was surveyed in 2003 and 2007 by airborne laser swath mapping (ALSM), enabling meter‐scale quantification of landscape change. We calculate four‐year volumetric flux from the earthflow and compare it to long‐term catchment average erosion rates from cosmogenic radionuclide inventories from adjacent watersheds. We also present detailed maps of changing features on the earthflow, from which we can derive velocity estimates and infer dominant process. These measurements rely on proper digital elevation model (DEM) generation and a simple surface‐matching technique to align the multitemporal data in a manner that eliminates systematic error in either dataset. The mean surface elevation of the earthflow and an opposite slope that was directly influenced by the earthflow decreased 14 ± 1 mm/yr from 2003 to 2007. By making the conservative assumption that these features were the dominant contributor of sediment flux from the entire Mill Gulch drainage basin during this time interval, we calculate a minimum catchment‐averaged erosion rate of 0·30 ± 0·02 mm/yr. Analysis of beryllium‐10 (¹⁰Be) concentrations in fluvial sand from nearby Russian Gulch and the South Fork Gualala River provide catchment averaged erosion rates of 0·21 ± 0·04 and 0·23 ± 0·03 mm/yr respectively. From translated landscape features, we can infer surface velocities ranging from 0·5 m/yr in the wide upper ‘source’ portion of the flow to 5 m/yr in the narrow middle ‘transport’ portion of the flow. This study re‐affirms the importance of mass wasting processes in the sediment budgets of uplifting weak lithologies. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Atmospheric Electrification in Dusty,Reactive Gases in the Solar System and Beyond     

Christiane Helling  R. Giles Harrison  Farideh Honary  Declan A. Diver  Karen Aplin  Ian Dobbs-Dixon  Ute Ebert  Shu-ichiro Inutsuka  Francisco J. Gordillo-Vazquez  Stuart Littlefair 《Surveys in Geophysics》2016,37(4):705-756

Detailed observations of the solar system planets reveal a wide variety of local atmospheric conditions. Astronomical observations have revealed a variety of extrasolar planets none of which resembles any of the solar system planets in full. Instead, the most massive amongst the extrasolar planets, the gas giants, appear very similar to the class of (young) brown dwarfs which are amongst the oldest objects in the Universe. Despite this diversity, solar system planets, extrasolar planets and brown dwarfs have broadly similar global temperatures between 300 and 2500 K. In consequence, clouds of different chemical species form in their atmospheres. While the details of these clouds differ, the fundamental physical processes are the same. Further to this, all these objects were observed to produce radio and X-ray emissions. While both kinds of radiation are well studied on Earth and to a lesser extent on the solar system planets, the occurrence of emissions that potentially originate from accelerated electrons on brown dwarfs, extrasolar planets and protoplanetary disks is not well understood yet. This paper offers an interdisciplinary view on electrification processes and their feedback on their hosting environment in meteorology, volcanology, planetology and research on extrasolar planets and planet formation.  相似文献   

Urban social vulnerability assessment with physical proxies and spatial metrics derived from air- and spaceborne imagery and GIS data   总被引：2，自引：0，他引：2  

Annemarie Ebert  Norman Kerle  Alfred Stein 《Natural Hazards》2009,48(2):275-294

Risk management in urban planning is of increasing importance to mitigate the growing amount of damage and the increasing number of casualties caused by natural disasters. Risk assessment to support management requires knowledge about present and future hazards, elements at risk and different types of vulnerability. This article deals with the assessment of social vulnerability (SV). In the past this has frequently been neglected due to lack of data and assessment difficulties. Existing approaches for SV assessment, primarily based on community-based methods or on census data, have limited efficiency and transferability. In this article a new method based on contextual analysis of image and GIS data is presented. An approach based on proxy variables that were derived from high-resolution optical and laser scanning data was applied, in combination with elevation information and existing hazard data. Object-oriented image analysis was applied for the definition and estimation of those variables, focusing on SV indicators with physical characteristics. A reference Social Vulnerability Index (SVI) was created from census data available for the study area on a neighbourhood level and tested for parts of Tegucigalpa, Honduras. For the evaluation of the proxy-variables, a stepwise regression model to select the best explanatory variables for changes in the SVI was applied. Eight out of 47 variables explained almost 60% of the variance, whereby the slope position and the proportion of built-up area in a neighbourhood were found to be the most valuable proxies. This work shows that contextual segmentation-based analysis of geospatial data can substantially aid in SV assessment and, when combined with field-based information, leads to optimization in terms of assessment frequency and cost.  相似文献   

Microstructures of coarse-grained marbles,analyzed using a new technique based on the bireflectance of calcite     

A. Ebert  D. Rieke-Zapp  M. Herwegh  K. Ramseyer  E. Gnos  D. Decrouez 《Tectonophysics》2009,463(1-4):175-184

A new approach to quantify microstructures of coarse-grained marbles is presented. This technique is based on the intensity of light reflectance in dependence of the crystallographic orientation of calcite grains. The technique setup consists of a high-resolution camera, a strong light source and the polished sample in reflection position. Microstructural data obtained with this method are comparable with those obtained by light microscopy or by secondary electron microscopy. However, the new approach reflects the grain size distribution even more accurately than in the case of other techniques, because it allows an easy quantification of larger sample surfaces. Therefore, in contrast to established techniques, microstructural analysis and statistics can also be performed for coarse-grained samples with grains that exceed diameters of 1 cm. With this new technique, coarse-grained mylonitic microstructures from Naxos were quantified, which in turn allowed relating different microfabrics to different strain localization episodes within a large-scale shear zone complex.  相似文献   

Silicate liquid immiscibility in impact melts          下载免费PDF全文

Christopher Hamann  Agnese Fazio  Matthias Ebert  Lutz Hecht  Richard Wirth  Luigi Folco  Alex Deutsch  Wolf Uwe Reimold 《Meteoritics & planetary science》2018,53(8):1594-1632

We have investigated silicate emulsions in impact glasses and impact melt rocks from the Wabar (Saudi Arabia), Kamil (Egypt), Barringer (USA), and Tenoumer (Mauritania) impact structures, and in experimentally generated impact glasses and laser-generated glasses (MEMIN research unit) by scanning electron microscopy, electron microprobe analysis, and transmission electron microscopy. Textural evidence of silicate liquid immiscibility includes droplets of one glass disseminated in a chemically distinct glassy matrix; sharp phase boundaries (menisci) between the two glasses; deformation and coalescence of droplets; and occurrence of secondary, nanometer-sized quench droplets in Si-rich glasses. The compositions of the conjugate immiscible liquids (Si-rich and Fe-rich) are consistent with phase separation in two-liquid fields in the general system Fe₂SiO₄–KAlSi₃O₈–SiO₂–CaO–MgO–TiO₂–P₂O₅. Major-element partition coefficients are well correlated with the degree of polymerization (NBO/T) of the Si-rich melt: Fe, Ca, Mg, and Ti are concentrated in the poorly polymerized, Fe-rich melt, whereas K, Na, and Si prefer the highly polymerized, Si-rich melt. Partitioning of Al is less pronounced and depends on bulk melt composition. Thus, major element partitioning between the conjugate liquids closely follows trends known from tholeiitic basalts, lunar basalts, and experimental analogs. The characteristics of impact melt inhomogeneity produced by melt unmixing in a miscibility gap are then compared to impact melt inhomogeneity caused by incomplete homogenization of different (miscible or immiscible) impact melts that result from shock melting of different target lithologies from the crater's melt zone, which do not fully homogenize and equilibrate due to rapid quenching. By taking previous reports on silicate emulsions in impact glasses into account, it follows that silicate impact melts of variable composition, cooling rate, and crystallization history might readily unmix during cooling, thereby rendering silicate liquid immiscibility a much more common process in the evolution of impact melts than previously recognized.  相似文献   

Bemerkung zu den Vorträgen Backlund und Eskola     

H. Ebert 《International Journal of Earth Sciences》1936,27(1):74-75

Ohne Zusammenfassung  相似文献   

Analysis of the water column oxic/anoxic interface in the Black and Baltic seas with a numerical model     

E.V. Yakushev  F. Pollehne  G. Jost  I. Kuznetsov  B. Schneider  L. Umlauf 《Marine Chemistry》2007

A 1D hydrophysical-biogeochemical model was developed to study the cycling of the main elements in the pelagic redox layer in seas with anoxic conditions. The formation and decay of organic matter; the reduction and oxidation of nitrogen, sulfur, manganese, and iron species; and the transformation of phosphorus species were parameterized. Temporal and spatial developments of the model's variables were described by a system of horizontally integrated vertical diffusion equations for non-conservative substances. The calculated spatial and temporal distributions of the above-mentioned parameters were in good agreement with observed vertical distribution patterns of these processes.  相似文献   

U–Pb SHRIMP and Sm–Nd geochronology of granite–gneiss complexes and implications for the evolution of the Central Brazil Archean Terrain     

Cludia Lima Queiroz  Hardy Jost  Luiz Carlos da Silva  Neal J. McNaughton 《Journal of South American Earth Sciences》2008,26(1):100-124

The paper is a first attempt to unravel the Archean multi-stage metaplutonic assemblage of the Meso/Neoarchean terrane of the State of Goiás, Central Brazil, by means of the U–Pb SHRIMP zircon and Sm–Nd techniques. Two stages of granitic plutonism, spanning ca. 140 m.y., were precisely established for the accretion of the gneiss protoliths. The earliest stage embraces tonalitic to granodioritic and minor granitic orthogneisses with Nd juvenile signature, emplaced from ca. 2845 to ca. 2785 Ma, interpreted as the roots of an early arc. Inherited zircon xenocrysts and Nd isotopic data indicate that the juvenile magmas underwent contamination from a sialic crust as old as 3.3 Ga, from which there are, so far, no recognizable exposures. The second stage comprises granodioritic to granitic gneisses and lasted from ca. 2711 to 2707 Ma. Based on their Nd isotopic signatures and on inherited zircon crystals, their protoliths are interpreted as dominantly crustal-derived. The SHRIMP data from zircon crystals did not depict a Paleoproterozoic overprinting on the Archean gneisses, which is due to geological processes with prevailing temperatures below the isotopic stability of the U/Pb/Th system in the mineral. These processes comprise crustal extension and intrusion of a mafic dike swarm at ca. 2.3 Ga, followed by low grade events mostly related to shear zones between ca. 2.15 and 2.0 Ga. The study also revealed the extent of the Pan- African tectono-thermal overprinting on the Archean orthogneisses. Most of the zircon populations show morphological evidence of metamorphic peripheral recrystallization dated between ca. 750 and 550 Ma. One of the banded gneisses with a crystallization age of ca. 2700 Ma (2σ) has a more complex zircon population including magmatic new grains, which yielded a precise 206Pb/238U crystallization age of 590 ± 10 Ma (2σ). These new grains are interpreted to have grown in anatectic veins injected within strongly sheared gneiss.The data characterize a widespread Pan-African-aged metamorphic overprinting, culminating with localized anatexis of the Archean orthogneisses.  相似文献