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251.
252.
Comparison of modelled- and remote sensing- derived daily snow line altitudes at Ulugh Muztagh,northern Tibetan Plateau 总被引:1,自引:0,他引:1
The ice cap Ulugh Muztagh in the central Kunlun Shan at the northern fringe of the Tibetan Plateau is a very isolated region with arid cold conditions. No observational, meteorological or glaciological ground truth data is available. Using the Moderate-resolution Imaging Spectroradiometer(MODIS) Level 1 radiance Swath Data(MOD02QKM) with a spatial resolution of 250 m, transient snow lines during the months of July to September in 2001 to 2014 are derived. Results are used to calibrate the physical based Coupled Snowpack and Ice surface energy and Mass balance model(COSIMA). The model runs on a representative detail region of Ulugh Muztagh(UM) on a digital elevation model with the same spatial resolution as the MODIS bands. In the absence of field observations, the model is driven solely by dynamically downscaled global analysis data from the High Asia Refined analysis(HAR). We compare remote sensing derived and modelled mean regional transient snow line altitudes in the course of consecutive summer seasons in 2008 to 2010. The resulting snow line altitude(SLA) and annual equilibrium line altitude(ELA) proxy of both methods coincide very well in their interannual variability in accordance with interannual variability of climatic conditions. Since SLAs of both methods do notconsistently agree on a daily basis a usage of remote sensing derived SLAs for model calibration in the absence of field observation data is only limitedly feasible for daily analysis. ELA approximation using the highest SLA at the end of ablation period may not be applied to UM because the negative winter mass balance(MB) is not reflected in the summer SLA. The study reveals moderate negative MB for UM throughout the modelling period. The mean regional MB of UM accounts for-523±410 mm w.e. a-1 in the modelling period. Hence UM seems not to belong to the area of the ‘Karakorum anomaly' comprising a region of positive mass balances in recent years which has its centre presumably in the Western Kunlun Shan. 相似文献
253.
Pre-processing of a sample of multi-scene and multi-date Landsat imagery used to monitor forest cover changes over the tropics 总被引:1,自引:0,他引:1
Catherine BodartHugh Eva René Beuchle Rastislav RašiDario Simonetti Hans-Jürgen StibigAndreas Brink Erik LindquistFrédéric Achard 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(5):555-563
In support to the Remote Sensing Survey of the global Forest Resource Assessment 2010, the TREES-3 project has processed more than 12,000 Landsat TM and ETM+ data subsets systematically distributed over the tropics. The project aims at deriving area estimates of tropical forest cover change for the periods 1990-2000-2005. The paper presents the pre-processing steps applied in an operational and robust manner to this large amount of multi-date and multi-scene imagery: conversion to top-of-atmosphere reflectance, cloud and cloud shadow detection, haze correction and image radiometric normalization. The results show that the haze correction algorithm has improved the visual appearance of the image and significantly corrected the digital numbers for Landsat visible bands, especially the red band. The impact of the normalization procedures (forest normalization and relative normalization) was assessed on 210 image pairs: in all cases the correlation between the spectral values of the same land cover in both images was improved. The developed automatic pre-processing chain provided a consistent multi-temporal data set across the tropics that will constitute the basis for an automatic object-based supervised classification. 相似文献
254.
Slavomír Nehyba Daniel Nývlt Uwe Schkade Gerald Kirchner Eva Franců 《Journal of Paleolimnology》2011,45(1):41-55
Facies analysis, magnetic susceptibility, and analysis of grain size, TOC content and isotopes (137Cs, 210Pb, 226Ra, 228Ra, and 238U concentrations) were used to determine the history of the modern deposits of the Brno reservoir. The sedimentary succession
can be subdivided into two main units. The lower unit is formed predominantly by medium- to coarse-grained silty sands and
is interpreted as a fluvial succession deposited before the Svratka River was dammed. The upper unit consists of brownish
planar laminated silts and rarely of clayey or sandy silts and is interpreted as a product of the reservoir deposition. The
concentrations of 238U reflect the history of uranium mining in the upper part of the Svratka River catchment. As a consequence, 210Pb radionuclide concentrations cannot be used for establishing a sediment chronology. Concentrations of 137Cs show two marked peaks, the upper of which is attributed to the Chernobyl reactor accident in 1986, and the lower one is
attributed to the maximum rate of atomic weapons testing in 1963. From these peaks, mean depositional rates of 3.2 cm year−1 for the time period of 1986–2007 and of 3.4 cm year−1 between 1963 and 1986 are calculated. Based on the known age of the reservoir, which was constructed in 1939, we can also
calculate mean depositional rate for the time period of 1939–1963, which is 3.1 cm year−1. 相似文献
255.
256.
Rodrigo Rier Juan Domingo Delgado Myriam Rodrguez scar Monterroso Eva Ramos 《海洋学报(英文版)》2012,31(1):98-105
This study contributes with the first data on physical and taxonomical structure of macrofaunal assemblages of ma¨erl beds from the Canary Islands. Ma¨erl beds and Cymodocea nodosa meadows of the Canary Islands are considered biodiversity hot-spots in terms of taxonomic and functional biodiversity with a broad geographical and depth ranges. The authors have studied the structure of the macrofaunal assemblages on different habitat types (Cymodocea, Caulerpa, sabellid field, garden eel and ma¨erl beds). Samples were taken at a range of depths between 14 and 46 m. Correlations were performed among abiotic variables (granulometry, organic matter, nitrogen and phosphates) and the most abundant taxa. Similarity analysis was performed to explore the patchiness of seabeds at a local scale. Significant differences were found in macrofaunal assemblages among seabed types, with highest abundances and lowest biodiversity in sabellid fields, where the sabellid Bispira viola dominated. The polychaetes Aponuphis bilineata and Chone filicauda and the mollusc Turritella brochii were the most abundant taxa on ma¨erl beds. The mosaic of granulometric conditions would explain the associated macroinfaunal community structure and contribute to the creation of diversity on these relatively well preserved seabeds at a local scale. 相似文献
257.
Large-scale coronal structures (helmet streamers) observed in the white-light corona during total solar eclipses and/or with
ground-based coronagraphs are mostly located only above quiescent types of prominences. These helmet streamers are maintained
due to the magnetic fields of the Sun. Time–latitudinal distribution of prominences during a solar cycle, however, shows both
the poleward and equatorward migrations, similar to the 530.3 nm emission corona (the green corona) intensities. Distribution
of observed coronal helmet streamers during total solar eclipses, enlarged with the helmet streamers as were obtained by the
ground-based coronagraph observations, are compared with the heliographic distribution of prominences and the green corona
intensities for the first time. It is shown that the distribution of above-mentioned helmet streamers, reflects – roughly
– the time–latitudinal distribution of prominences and emission corona branches, and migrates together with them over a solar
cycle. 相似文献
258.
259.
Juraj Tóth Ján Svoreň Jiří Borovička Pavel Spurný Antal Igaz Leonard Kornoš Peter Vereš Marek Husárik Július Koza Aleš Kučera Pavel Zigo Štefan Gajdoš Jozef Világi David Čapek Zuzana Krišandová Dušan Tomko Jiří Šilha Eva Schunová Marcela Bodnárová Diana Búzová Tereza Krejčová 《Meteoritics & planetary science》2015,50(5):853-863
We provide the circumstances and details of the fireball observation, search expeditions, recovery, strewn field, and physical characteristics of the Ko?ice meteorite that fell in Slovakia on February 28, 2010. The meteorite was only the 15th case of an observed bolide with a recovered mass and subsequent orbit determination. Despite multiple eyewitness reports of the bolide, only three videos from security cameras in Hungary were used for the strewn field determination and orbit computation. Multiple expeditions of professionals and individual searchers found 218 fragments with total weight of 11.3 kg. The strewn field with the size of 5 × 3 km is characterized with respect to the space distribution of the fragments, their mass and size‐frequency distribution. This work describes a catalog of 78 fragments, mass, size, volume, fusion crust, names of discoverers, geographic location, and time of discovery, which represents the most complex study of a fresh meteorite fall. From the analytical results, we classified the Ko?ice meteorite as an ordinary H5 chondrite. 相似文献
260.
Fabrizio Eva 《GeoJournal》2000,52(2):295-301
Discussion of the future of Europe continues to be a marginal political issue, partly because of the resistance of states, on both the practical (bureaucratic) and conceptual levels, created by the government leaders and heads of state. In turn, the nation-states are challenged from within by independent and separatist movements that have laid bare the fundamental hypocrisy of rhetorical discussions of the principle regarding the self-determination of peoples; interfering with states (and their borders) has proven to be a taboo for Europe. The growing flexibility of the globalised economy should be paralleled by a growing flexibility in the conception of the division and political organisation of territory, but this is not the case. Further inflexibility stems from the socio-economic inequity that we accept in our daily lives as normal, in particular as regards inequality in the use and division of territory. Equality, or better egaliberté (equality and liberty), is a sufficiently dynamic and flexible concept to be taken as a point of reference in envisaging the society, Europe, and world of tomorrow. It is only through the concept of egaliberté that we can imagine a Europe based on relations between regions that are conceived and organised on multiple scales and not as region-nations conceived on the basis of ethnicity or in the name of supposed cultural homogeneity. 相似文献