Combined influence of PDO and ENSO on northern Andean glaciers: a case study on the Cotopaxi ice-covered volcano,Ecuador     

Bijeesh Kozhikkodan Veettil  Éder Leandro Bayer Maier  Ulisses Franz Bremer  Sergio Florencio de Souza 《Climate Dynamics》2014,43(12):3439-3448

This paper describes the application of remote sensing in monitoring the fluctuations in one of the mountain glaciers in the Ecuadorean Andes during the past few decades using ASTER, EO-1 ALI, Landsat MSS, TM and ETM + images. Satellite images were used to calculate the snow line altitudes (SLAs) during the period 1979–2013. Cotopaxi ice covered volcano was studied as representative of Ecuadorian glaciers in the eastern cordillera. Precipitation and air temperature data from various gauging stations within the range of 30 km from the study site and monthly discharge and water level data from a gauging station were also utilized in this study. Anomalies in precipitation and temperature were found to be slightly different in the Cotopaxi region compared to nearby Antizana in the same cordillera and Chimborazo region in the western cordillera. An attempt to correlate the El Niño—southern oscillation phenomenon with the glacier fluctuations in Ecuadorian Andes was done successfully. Cold and warm regimes of Pacific Decadal Oscillation is also considered. The calculated glacier fluctuations obtained were similar to that performed on the nearby Antizana 15 in the eastern cordillera during 1995–2002. Precipitation and temperature anomalies were similar with Antizana 15. It is evident from the research that SLAs were highly fluctuated between the period of occurrence of El Niño and La Niña events. It is also seen that the glacier fluctuations show a negative mass balance trend in during the warm regime of Pacific Decadal Oscillation during the past three decades. Glaciated areas were advanced during the La Nina events in the cold regime of PDO during 1998–2002.  相似文献   

Constraining clastic input controls on magnetic susceptibility and trace element anomalies during the Late Devonian punctata Event in the Western Canada Sedimentary Basin     

Maciej G. Śliwiński  Michael T. Whalen  Franz J. Meyer  František Majs 《地学学报》2012,24(4):301-309

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Uniform Permian 40Ar/39Ar detrital mica ages in the eastern Qaidam Basin (NW China): where is the source?     

Andrea B. Rieser  Yongjiang Liu  Johann Genser  Franz Neubauer  Robert Handler  Xiao‐Hong Ge 《地学学报》2006,18(1):79-87

New single‐grain ⁴⁰Ar/³⁹Ar detrital white‐mica ages from the Lulehe section at the eastern Qaidam Basin yield uniform Permian ages between 250 ± 3 and 279 ± 3 Ma throughout the whole Cenozoic sequence. This is inconsistent with the present hinterland, which is composed of early Palaeozoic metamorphic units with subordinate early Palaeozoic and few Permian granites. The new data indicate that Permian tectonic units are likely more widespread at the north‐eastern margin of the Tibetan plateau as known at present, particularly within the Qilian Mountains. The preferred explanation is that the Qaidam block represents a rigid indenter, which indented during late Tertiary times into early Palaeozoic orogenic units. This is consistent with recent findings of a NW‐trending sinistral Permian ductile shear zone and a dextral, NW‐trending Tertiary fault system close to the north‐eastern margin of the Qaidam Basin.  相似文献   

Hidden subluminous stars among the FAUST UV sources towards Ophiuchus     

Liliana Formiggini  Noah Brosch  Elchanan Almoznino  Stuart Bowyer  Michael Lampton 《Monthly notices of the Royal Astronomical Society》2002,332(2):441-455

We present results of an analysis of a UV image in the direction of Ophiuchus, obtained with the FAUST instrument. The image contains 228 UV sources. Most of these are identified as normal early-type stars through correlations with catalogued objects. For the first time in this project we identify UV sources as such stars by selecting suitable candidates in crowded fields as the bluest objects in colour–colour diagrams using observations from the Wise Observatory. These candidates are then studied using low-resolution spectroscopy, which allows the determination of spectral types to an accuracy of about one-half class, for 60 stars.
Synthetic photometry of spectral data is performed in order to predict the expected UV emission, on the basis of the photometric information. These results are used along with the Hipparcos /Tycho information, to search for subluminous stars. The comparison of the predicted emission with the FAUST measured magnitudes allows us to select 12 stars as highly probable evolved hot stars. High signal-to-noise spectra are obtained for nine of these stars, and Balmer line profiles are compared with the prediction of atmosphere models and with the spectrum of real stellar atmospheres. Among the nine candidates, six are classified as previously unrecognized sdB stars, and two as white dwarfs. Our result indicates that indeed more bright subluminous stars are still unrecognized in the existing samples.  相似文献   

Synthetic Spectra of Long-Period Variables: A First Comparison with ISO Observations     

Rita Loidl  Josef Hron  Susanne Höfner  Uffe G. ørgensen  Bernhard Aringer  Franz Kerschbaum 《Astrophysics and Space Science》1997,251(1-2):243-246

Exploratory synthetic spectra were computed for carbon-rich long-period variables. We used dynamic model atmospheres of Höfner &; Dorfi (1997) and calculated partial pressures, absorption- and scattering coefficients as input for the spectral synthesis code of Jørgensen et al. (1992). First ISO SWS-observations of the carbon-Mira T Dra are compared with our synthetic spectra.  相似文献   

‘PALEOVAN’, International Continental Scientific Drilling Program (ICDP): site survey results and perspectives     

Thomas Litt  Sebastian Krastel  Michael Sturm  Rolf Kipfer  Sefer Örcen  Georg Heumann  Sven Oliver Franz  Umut B. Ülgen  Frank Niessen 《Quaternary Science Reviews》2009,28(15-16):1555-1567

Lake Van is the fourth largest terminal lake in the world (volume 607 km³, area 3570 km², maximum depth 460 m), extending for 130 km WSW–ENE on the Eastern Anatolian High Plateau, Turkey. The sedimentary record of Lake Van, partly laminated, has the potential to obtain a long and continuous continental sequence that covers several glacial–interglacial cycles (ca 500 kyr). Therefore, Lake Van is a key site within the International Continental Scientific Drilling Program (ICDP) for the investigation of the Quaternary climate evolution in the Near East (‘PALEOVAN’). As preparation for an ICDP drilling campaign, a site survey was carried out during the past years. We collected 50 seismic profiles with a total length of ～850 km to identify continuous undisturbed sedimentary sequences for potential ICDP locations. Based on the seismic results, we cored 10 different locations to water depths of up to 420 m. Multidisciplinary scientific work at positions of a proposed ICDP drill site included measurements of magnetic susceptibility, physical properties, stable isotopes, XRF scans, and pollen and spores. This core extends back to the Last Glacial Maximum (LGM), a more extended record than all the other Lake Van cores obtained to date. Both coring and seismic data do not show any indication that the deepest part of the lake (Tatvan Basin, Ahlat Ridge) was dry or almost dry during past times. These results show potential for obtaining a continuous undisturbed, long continental palaeoclimate record. In addition, this paper discusses the potential of ‘PALEOVAN’ to establish new results on the dynamics of lake level fluctuations, noble gas concentration in pore water of the lake sediment, history of volcanism and volcanic activities based on tephrostratigraphy, and paleoseismic and earthquake activities.  相似文献   

Coeval Lower Miocene subsidence of the Eisenstadt Basin and relative updoming of its Austroalpine frame: implications from high-resolution geophysics at the Oslip section (Northern Burgenland,Austria)     

Hermann Häusler  Jürgen Scheibz  Werner Chwatal  Franz Kohlbeck 《International Journal of Earth Sciences》2015,104(2):475-493

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Technologies and science archives for ultraviolet astronomy     

Noah Brosch  Martin Barstow  Jose Chirivella 《Astrophysics and Space Science》2014,354(1):125-141

This paper summarizes 17 talks presented during the Technological sessions at the “Challenges in UV Astronomy” conference. It is based on summaries submitted by the presenters, on the slides of their talks, on notes written by the authors, and on additional material kindly submitted to the lead author. In many instances the summaries were written by the presenters themselves and are included as-submitted to the authors with just minor editorial interference. In other cases one of the editors wrote the summary based on their notes and on the files of the actual presentations. The contributions are placed in the general context of the current knowledge in the field. The sessions were devoted to: [a] detectors, [b] optics, [c] integration and verification procedures for vacuum UV instruments and [d] calibration and archival research. A cautionary note: this is not a regular article in these proceedings presenting one idea, an experiment, of a result. It is rather a distillation of what was presented at the NUVA/ESO/IAG meeting at the sessions deemed technological, therefore it will lack an overall coherence although the individual sections and subsections should be logically connected.  相似文献   

Neighbourhoods of isolated star forming dwarf galaxies     

Noah Brosch  Carmiya Bar-Or  Doron Malka 《Monthly notices of the Royal Astronomical Society》2006,368(2):864-876

We report the discovery of small groups of uncatalogued, compact, star forming (SF) dwarf galaxies (DGs) by Hα mapping of the neighbourhoods of apparently isolated, catalogued, SF DGs. Our sample consists of dwarf  ( M ≥−18 mag)  galaxies at least 2 Mpc away from any other catalogued galaxy. The galaxies were selected to exhibit Hα emission of any intensity, i.e. not selecting only strong starbursts, as an indicator of recent or on-going star formation with the goal of understanding why are they presently forming stars. We identified possible neighbours by imaging the galaxies and their surroundings through Hα filters centred at or near the redshift of the galaxy, and searching for localized Hα emission with the characteristics of the line emission from the sample galaxies.
We identified 20 possible SF neighbour galaxies, 17 of them not previously catalogued, in three of the five search fields where we had good quality data, and present here their positions and, images and morphology, as well as some indications of binarity. The relatively large number of possible neighbour candidates, combined with their relative faintness, argue that it would be virtually impossible to identify truly isolated galaxies. It seems that the objects we selected as extremely isolated are probably the brightest members of sparse groups of galaxies, where the other members are also DGs that are presently forming stars. In order to enhance the confidence of this statement regular redshifts are required for our candidate neighbours.  相似文献   

Integrated and Participatory Research Approaches towards Sustainable Livelihoods and Ecosystems in Mountainous Regions     

Andreas Neef Franz Heidhues Karl Stahr David Thomas Pittaya Sruamsiri 《山地科学学报》2006,3(4):271-275

Mountainous regions cover about 27 per cent of the world’s land surface and are home to some 22 per cent of the global population (UNEP 2002). A much greater number of people depend on mountain environments for a wide range of services, including clean water, energy, timber, biodiversity, recreation, and protection from environmental hazards, such as landslides and floods. At the same time, mountain areas are extremely vulnerable ecosystems and under continuous threat of environmental degrad…  相似文献