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11.
Sedef Cakir Mikdat Kadioglu Nihat Cubukcu 《Theoretical and Applied Climatology》2013,111(3-4):703-711
The ensemble method has long been used to reduce the errors that are caused by initial conditions and/or parameterizations of models in forecasting problems. In this study, neural network (NN) simulations are applied to ensemble weather forecasting. Temperature forecasts averaged over 2 weeks from four different forecasts are used to develop the NN model. Additionally, an ensemble mean of bias-corrected data is used as the control experiment. Overall, ensemble forecasts weighted by NN with feed forward backpropagation algorithm gave better root mean square error, mean absolute error, and same sign percent skills compared to those of the control experiment in most stations and produced more accurate weather forecasts. 相似文献
12.
We have compared the observed distribution of the quantity log(V
2
2
rP) for a sample of 233 pairs of galaxies with Monte-Carlo simulations. From such an analysis we have derived an average mass-to-luminosity ratiosM/L
B
=18±11. Our result is consistent with a linear increase of the mass with radius at least until distances of about 30 kpc. 相似文献
13.
Cenk Yalt?rak Umut B. ülgen Cengiz Zabc? Sven Oliver Franz Sena Ak?er ?n Mehmet Sak?n? M. Nam?k ?a?atay Bedri Alpar Kurultay ?ztürk Cemal Tuno?lu Selma ünlü 《Geo-Marine Letters》2012,32(3):267-274
The identification of past connection routes between the Black Sea and the Sea of Marmara, other than the traditional one through to the Bosphorus Strait, would be of considerable interest to the international scientific community. Nazik et al. (Geo-Mar Lett 31:75?C86 (2011) doi:10.1007/s00367-010-0216-9) suggest the possibility of two alternative waterway connections via lakes Sapanca and ?znik. Their Black Sea to Sea of Marmara multi-connection hypothesis, which is based on undated marine fossils collected in both lakes from surficial grab samples, conflicts with many earlier studies. In this contribution, the hypothesis and the underlying data are discussed in the light of previous tectonic, sedimentological and limnological findings showing that it is impossible to have had marine connections through lakes Sapanca and ?znik during the last 11.5?ka. Global sea-level trends and tectonic uplift rates would accommodate a connection between the Sea of Marmara and Lake ?znik in the middle Pleistocene. Uplift rates for the northern block of the North Anatolian Fault, when compared with the global sea-level curve, clearly indicate that there cannot have been a connection through the ?zmit Gulf?CLake Sapanca?CSakarya Valley for at least the past 500?ka. Moreover, borehole sediments along the western shores of Lake Sapanca, which reach down to the bedrock, do not contain any marine fossils. 相似文献
14.
Multiple intertidal bars and troughs, often referred to as ‘ridges and runnels’, are significant features on many macrotidal sandy beaches. Along the coastline of England and Wales, they are particularly prevalent in the vicinity of estuaries, where the nearshore gradient is gentle and a large surplus of sediment is generally present. This paper examines the dynamics of such bar systems along the north Lincolnshire coast. A digital elevation model of the intertidal morphology obtained using LIDAR demonstrates that three to five intertidal bars are consistently present with a spacing of approximately 100 m. The largest and most pronounced bars (height = 0·5–0·8 m) are found around mean sea level, whereas the least developed bars (height = 0·2–0·5 m) occur in the lower intertidal zone. Annual aerial photographs of the intertidal bar morphology were inspected to try to track individual bars from year to year to derive bar migration rates; however, there is little resemblance between concurrent photographs, and ‘resetting’ of the intertidal profile occurs on an annual basis. Three‐dimensional beach surveys were conducted monthly at three locations along the north Lincolnshire coast over a one‐year period. The intertidal bar morphology responds strongly to the seasonal variation in the forcing conditions, and bars are least numerous and flattest during the more energetic winter months. Morphological changes over the monthly time scale are strongly affected by longshore sediment transport processes and the intertidal bar morphology can migrate along the beach at rates of up to 30 m per month. The behaviour of intertidal bars is complex and varies over a range of spatial and temporal scales in response to a combination of forcing factors (e.g. incident wave energy, different types of wave processes, longshore and cross‐shore sediment transport), relaxation time and morphodynamic feedback. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
15.
A new approximation in determination of zonation boundaries of ignimbrite by ground penetrating radar: Kayseri,Central Anatolia,Turkey 总被引：1，自引：1，他引：0
Ground penetrating radar (GPR) method is used as a tool to identify the zonation boundaries in ignimbrite series through their
columnar section. Ignimbrites can be classified in terms of welding degree, colour, texture and mineralogical compositions.
The research area comprises a part of İncesu (Kayseri) ignimbrite at Central Anatolia, Turkey. This ignimbrite is divided
into three levels and each level has clear differences in terms of macroscopic and microscopic views. This paper presents
the results of an application of GPR for the determination of zonation boundary within the ignimbrite flow unit in the view
of their textural and petrological features. RAMAC CU II equipment was used with 250 MHz shielded antenna on parallel ten
profiles to observe the physical difference among the ignimbrite levels of the study area. Two levels out of three have been
defined at the İncesu ignimbrite and supported by field geology and petrographical studies. The first level, which is extremely
fractured structure, is about 1.5 m thick and matches with middle level of the İncesu ignimbrite. The second level has an
average 50–75 cm thickness and matches with lower level of the ignimbrite. In this manner, vertical lithological variations
should be taken into consideration during petrological investigation of the ignimbrites. 相似文献
16.
Selma Etteieb Mounir Louhaichi Chariton Kalaitzidis Ioannis Z. Gitas 《Arabian Journal of Geosciences》2013,6(12):5017-5032
Mediterranean forests are characterized by spatiotemporal heterogeneity that is associated with Mediterranean climate, floristic biodiversity and topographic variability. Satellite remote sensing can be an effective tool for characterizing and monitoring forest vegetation distribution within these fragmented Mediterranean landscapes. The heterogeneity of Mediterranean vegetation, however, often exceeds the resolution typical of most satellite sensors. Hyper-spectral remote sensing technology demonstrates the capacity for accurate vegetation identification. The objective of this research is to determine to what extent forest types can be discriminated using different image analysis techniques and spectral band combinations of Hyperion satellite imagery. This research mapped forest types using a pixel-based Spectral Angle Mapper (SAM), nearest neighbour and membership function classifiers of the object-oriented classification. Hyperion classification was done after reducing Hyperion data using nine selected band combinations. Results indicate that the selection of band combination while reducing the Hyperion dataset improves classification results for both the overall and the individual forest type accuracy, in particular for the selected optimum Hyperion band combination. One shortcoming is that the performance of the best selected band combination was superior in terms of both overall and individual forest type accuracy when applying the membership classifier of the object-oriented method compared to SAM and nearest neighbour classifiers. However, all techniques seemed to suffer from a number of problems, such as spectral similarity among forest types, overall low energy response of the Hyperion sensor, Hyperion medium spatial resolution and spatiotemporal and spectral heterogeneity of the Mediterranean ecosystem at multiple scales. 相似文献
17.
Some earthquakes in the Eastern Mediterranean are tsunamigenic and some of their tsunamis affected the coastal area of the
Gulf of Fethiye, SW Turkey. Recent trenching surveys on the low-lying coastal areas of Dalaman delta beach across the Rhodes
Pass revealed three probable tsunami impacts as a result of the historical earthquakes of 1303, 1481 and 1741. Yet, there
have been relatively few studies of the processes associated with tsunami sediment transport, their deposition and nature
in geological record. In addition to the interpretation of sedimentary features, accurate paleoenvironmental assessments might
be possible by distinctive biogeochemical researches on marine-sourced organic matters, geochemical properties, quantitative
amounts of marine-sourced biomarkers and deterministic ratios. The identification of major lipid biomarkers (fatty acids and
sterols) in the samples recovered from the sidewalls of the studied trench, for example, indicated biogenic contributions
due to the presence of phytoplankton, zooplankton, dinoflagellates and bacteria. Quantitative estimation of biomarkers and
deterministic ratios also indicated some evidences for marine-sourced organic matters, implying that biomarkers can be used
to answer the open questions in tsunami and paleotsunami researches. 相似文献
18.
Robert A. Ayuso Antonia Messina Benedetto De Vivo Selma Russo Laurel G. Woodruff John F. Sutter Harvey E. Belkin 《Contributions to Mineralogy and Petrology》1994,117(1):87-109
The Sila batholith is the largest granitic massif in the Calabria-Peloritan Arc of southern Italy, consisting of syn to post-tectonic, calc-alkaline and metaluminous tonalite to granodiorite, and post-tectonic, peraluminous and strongly peraluminous, two-mica±cordierite±Al silicate granodiorite to leucomonzogranite. Mineral 40Ar/39Ar thermochronologic analyses document Variscan emplacement and cooling of the intrusives (293–289 Ma). SiO2 content in the granitic rocks ranges from 57 to 77 wt%; cumulate gabbro enclaves have SiO2 as low as 42%. Variations in absolute abundances and ratios involving Hf, Ta, Th, Rb, and the REE, among others, identify genetically linked groups of granitic rocks in the batholith: (1) syn-tectonic biotite±amphibole-bearing tonalites to granodiorites, (2) post-tectonic two-mica±Al-silicate-bearing granodiorites to leucomonzogranites, and (3) post-tectonic biotite±hornblende tonalites to granodiorites. Chondrite-normalized REE patterns display variable values of Ce/Yb (up to 300) and generally small negative Eu anomalies. Degree of REE fractionation depends on whether the intrusives are syn- or post-tectonic, and on their mineralogy. High and variable values of Rb/Y (0.40–4.5), Th/Sm (0.1–3.6), Th/Ta (0–70), Ba/Nb (1–150), and Ba/Ta (50–2100), as well as low values of Nb/U (2–28) and La/Th (1–10) are consistent with a predominant and heterogeneous crustal contribution to the batholith. Whole rock 18O ranges from +8.2 to +11.7; the mafic cumulate enclaves have the lowest 18O values and the two-mica granites have the highest values. 18O values for biotite±honblende tonalitic and granodioritic rocks (9.1 to 10.8) overlap the values of the mafic enclaves and two-mica granodiorites and leucogranites (10.7 to 11.7). The initial Pb isotopic range of the granitic rocks (206Pb/204Pb 18.17–18.45, 207Pb/204Pb 15.58–15.77, 208Pb/204Pb 38.20–38.76) also indicates the predominance of a crustal source. Although the granitic groups cannot be uniquely distinguished on the basis of their Pb isotope compositions most of the post-tectonic tonalites to granodiorites as well as two-mica granites are somewhat less radiogenic than the syn-tetonic tonalites and granodiorites. Only a few of the mafic enclaves overlap the Pb isotope field of the granitic rocks and are consistent with a cogenetic origin. The Sila batholith was generated by mixing of material derived from at least two sources, mantle-derived and crustal, during the closing stages of plate collision and post-collision. The batholith ultimately owes its origin to the evolution of earlier, more mafic parental magmas, and to complex intractions of the fractionating mafic magmas with the crust. Hybrid rocks produced by mixing evolved primarily by crystal fractionation although a simple fractionation model cannot link all the granitic rocks, or explain the entire spectrum of compositions within each group of granites. Petrographic and geochemical features characterizing the Sila batholith have direct counterparts in all other granitic massifs in the Calabrian-Peloritan Arc. This implies that magmatic events in the Calabrian-Peloritan Arc produced a similar spectrum of granitic compositions and resulted in a distinctive type of granite magmatism consisting of coeval, mixed, strongly peraluminous and metaluminous granitic magmas. 相似文献
19.
Photographing layer thicknesses and discontinuities in a marble quarry with 3D GPR visualisation 总被引：1，自引：0，他引：1
An important problem of marble-quarry management is assessing the quality and the homogeneity of quarry blocks before excavation. In this study, we decided to image the limestone, which we studied in a marble quarry, in terms of layer thickness, discontinuities and cavities using the ground-penetrating-radar (GPR) method. The method was successfully applied to detect and map the fractures with the cavities in a marble layer according to depth in the Ankara City Polatli Town (Turkey) region, which represents upper Miocene–Pliocene lacustrine carbonate rocks.This paper is based on interactive transparent 3D visualisation of the 2D GPR profiles to determine changes in layer thickness and discontinuities. In addition, this paper indicates the importance of the appropriate opacity-function construction to obtain transparent 3D visualisation. Firstly we acquired and processed parallel 2D GPR profile data, then we assigned two different amplitude–colour ranges using a limited number of colours to determine the layer thickness and its discontinuities separately. We obtained a 3D volume using parallel 2D GPR data and displayed a limited amplitude range by arranging an opacity function. Therefore, we obtained transparent 3D blocks for thickness and discontinuities, and we formulated an interactive 3D display to image the horizontal, vertical and inclined discontinuities and their directions in the x–y plane versus depth. The GPR results were compared with the petrographical investigation on the basis of textural and mineralogical compositions. The vesicular textures within carbonate platform were supported by the GPR results. 相似文献
20.
The Central Anatolian Volcanic Province (CAVP), one of four major volcanic provinces in Turkey, plays a significant role in the interpretation of the tectonic evolution of Central Anatolia. The CAVP developed within a complex collisional system involving the African, Arabian and Eurasian plates during the Miocene. The volcanism exhibits complicated variations in mineralogical, petrological and geochemical compositions resulting from post-collisional lithospheric dynamics. The Incesu ignimbrite has 5–20 m thick and covers an area of ～7800 km2. It is composed of three stratigraphic levels. The lower level (LL) shows blackish brown and glassy welded structure. The middle level (ML) is a well-welded, reddish pink in color and has large amounts of fiamme. The upper level (UL) is grayish pink, weakly welded and has rock fragments of different compositions. The Incesu ignimbrite is composed of plagioclase (oligoclase, andesine) + pyroxene (augite, clinoenstatite) + opaque minerals and low amount of amphibole, biotite and quartz. Eutaxitic texture is dominant in ML and LL samples; these levels are more strongly and contain more flattened pumice fragments and volcanic glass shards than in the UL. A sharp color contrast defines the contact between LL and ML.Major, trace and rare earth element of the Incesu ignimbrite, characterized by their rhyolite, rhyodacite–dacite composition, medium–high K, calcalkaline and peraluminous nature, show fractional crystallization primarily controlled by plagioclase, clinopyroxene, magnetite, ilmenite and titanomagnetite. Sr and Nd isotopic ratios of Incesu ignimbrite display isotopic variations between the ignimbrite levels; they exhibit a limited range in 87Sr/86Sr (0.7043–0.7049) and 143Nd/144Nd (0.512716–0.512760). The Sr–Nd isotopic ratio of Incesu ignimbrite reveals an age of 3 Ma. The ignimbrite evolved through fractional crystallization and crystal contamination of the parent magma derived from Ocean Island Basalt (OIB) like magma. This suggestion is supported by the AFC modeling based on the trace elements and Sr isotope data.Variation of several major oxide concentrations (Fe2O3, TiO2, CaO and K2O), trace element concetrations (V, Sr, Cs and Rb) and trace element ratios (Ba/Rb, Sr/, K/Sr, K/Nb, Rb/Sr, Rb/Y and Rb/Nb) versus SiO2 concentration show the magma chamber that generated the Incesu ignimbrite was compositionally zoned. All geochemical and Sr–Nd isotpic datas can be interepreted to be the result of a subduction related source. 相似文献