High resolution images of Cygnus X-1     

Alastair Stirling  Ralph Spencer  Mike Garrett 《New Astronomy Reviews》1998,42(9-10)

The classic black hole candidate Cygnus X-1 exhibits many similarities to Galactic jet sources (micro-quasars) in soft gamma and hard X-ray rays. This has fuelled suspicions that radio jets also may be present in Cygnus X-1. The lack of radio flaring in Cygnus X-1 has been associated with the presence of continuous jets rather than multiple plasmon ejection however no evidence for this has been observed with the VLA, or with MERLIN. Recent VLBA observations at 15 GHz have detected extended emission and further multi frequency observations are required to confirm the presence of jets on a milliarcsecond level.  相似文献   

The Baltic Sea Experiment BALTEX: A brief overview and some selected results of the authors     

Ehrhard Raschke  Ute Karstens  Ralph Nolte-Holube  Rüdiger Brandt  Hans-Jörg Isemer  Dag Lohmann  Manfred Lobmeyr  Burkhardt Rockel  Rolf Stuhlmann 《Surveys in Geophysics》1998,19(1):1-22

The mechanisms responsible for the transfer of energy and water within the climate system are under worldwide investigation within the framework of the Global Energy and Water Cycle Experiment (GEWEX) to improve the predictability of natural and man-made climate changes at short and long ranges and their impact on water resources. Five continental-scale experiments have been established within GEWEX to enable a more complete coupling between atmospheric and hydrological models. One of them is the Baltic Sea Experiment (BALTEX).In this paper, the goals and structure of BALTEX are outlined. A short overview of measuring and modelling strategies is given. Atmospheric and hydrological model results of the authors only are presented. These include also the validation of precipitation using station measurements as well as validation of modelled cloud cover with cloud estimates from satellite data. Furthermore, results of a large-scale grid based hydrological model to be coupled to atmospheric models are presented.This research has never been possible without the contribution of research groups and operational institutions from all 10 member countries. We concentrate here on results obtained at the GKSS research center.  相似文献   

Imaging of structures in the high-latitude ionosphere: model comparisons     

D. W. Idenden  R. J. Moffett  M. J. Williams  P. S. J. Spencer  L. Kersley 《Annales Geophysicae》1998,16(8):969-973

The tomographic reconstruction technique generates a two-dimensional latitude versus height electron density distribution from sets of slant total electron content measurements (TEC) along ray paths between beacon satellites and ground-based radio receivers. In this note, the technique is applied to TEC values obtained from data simulated by the Sheffield/UCL/SEL Coupled Thermosphere/Ionosphere/Model (CTIM). A comparison of the resulting reconstructed image with the input modelled data allows for verification of the reconstruction technique. All the features of the high-latitude ionosphere in the model data are reproduced well in the tomographic image. Reconstructed vertical TEC values follow closely the modelled values, with the F-layer maximum density (NmF2) agreeing generally within about 10%. The method has also been able successfully to reproduce underlying auroral-E ionisation over a restricted latitudinal range in part of the image. The height of the F2 peak is generally in agreement to within about the vertical image resolution (25 km).  相似文献   

Ray path-length-dependent slowness model     

Zhi Xie  Philip D. Rabinowitz  Terry W. Spencer 《Journal of Seismology》1998,2(4):317-322

By introducing a new parameter, slowness deviation, a ray-path-length-dependent slowness model has been previously developed. Synthetic tests indicate that for a horizontal layered slowness structure, the new model gives a good estimate of the weighted average slowness of a ray when the rays considered cover a small range of take-off angles. When the rays considered cover a large range of take-off angles, the new model gives good estimates of the weighted average slowness for the long rays, but large errors still remain for the short rays.  相似文献   

The clay-with-flints of the western Paris Basin: a potential aggregate resource     

Benoit Laignel  Christopher H. Spencer  Robert Meyer 《Environmental Geology》2002,41(5):525-536

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Erratum to: ‘Interhemispheric comparison of deglacial sea-surface temperature patterns in Atlantic eastern boundary currents’: [Earth Planet. Sci. Lett. 194 (2002) 383-393]     

Jung-Hyun Kim  Ralph R. SchneiderPeter J. Müller  Gerold Wefer 《Earth and Planetary Science Letters》2002,203(2):779-780

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Early 20th-century uplift of the northern Peninsular ranges province of southern California     

Spencer H. Wood  Michael R. Elliott 《Tectonophysics》1979,52(1-4)

Repeated leveling in the northern Peninsular Ranges province identifies an early 20thcentury episode of crustal upwarping in southern California. The episodic vertical movement is broadly bracketed between 1897 and 1934, and the main deformation is bracketed within 1906–1914 and involved regional up-to-the-northeast tilting of the Santa Ana block of as much as 4 · 10⁻⁶ rad and elevation changes exceeding 0.4 m in the Perris block and parts of the San Jacinto block, Transverse Ranges, and the Mohave block. Primary tide station records containing occasional entries since 1853 at San Pedro and San Diego show no evidence of episodic crustal movement, suggesting that the uplifted area hinged along coastal fault zones forming the west boundary of the Santa Ana block.Physiographic features and recent studies of Quaternary marine terraces by others show that this episode of regional tilting and uplift is a part of the continuing tectonic process in southern California. A crude, questionable coincidence exists between the uplift episode and a period of increased seismicity (1890–1923) in the northern Peninsular Ranges characterized by a number of moderate-size (M > 6) earthquakes on NW-trending strike-slip faults. However, releveling data are too sparse to associate the uplift development clearly with any one event.  相似文献   

Possibilities of agricultural settlements in the northern coastal area of Kenya —an analysis of relevant climatic factors     

Dr. Ralph Jaetzold 《GeoJournal》1978,2(3):225-242

Kenya is one of those African countries with a very high population pressure. In cultivatable areas we find up to 650 rural inhabitants per sq km. The search for new possibilities of agricultural settlement is an indispensable task. Many sciences are involved, also the geography of climates. Probably the largest potential settlement area from the climatic point of view is the Northern coastal zone. It has been settled in medieval times much more densely than today. War-like invasions of nomads have decreased the population since the 16th century. The average density of the cultivatable strip has been less than 5 inhabitants per sqkm in the last census year 1969. New settlement schemes have been developed since 1970, but they face the difficulty to choose the right varieties of crops. Careful climatic investigations are necessary for the further selection of areas and for the agricultural extension service. Here, only a first approach has been made. The main emphasis was laid on the effective rainfall in the so-called agrohumid period of the year and its probability. A new system of climatic classification was applied to give a frame for further, more specialised studies.  相似文献   

How long is coal's future?     

Ralph M. Rotty  Alvin M. Weinberg 《Climatic change》1977,1(1):45-57

Nearly all scenarios for future U.S. energy supply systems show heavy dependence on coal. The magnitude depends on assumptions as to reliance on nuclear fission, degree of electrification, and rate of GNP growth, and ranges from 700 million tons to 2300 million tons per year. However, potential climate change resulting from increasing atmospheric carbon dioxide concentrations may prevent coal from playing a major role. The carbon in the carbon dioxide produced from fossil fuels each year is about 1/10 the net primary production by terrestrial plants, but the fossil fuel production has been growing exponentially at 4.3% per year. Observed atmospheric CO₂ concentrations have increased from 315 ppm in 1958 to 330 ppm in 1974 - in 1900, before much fossil fuel was burned, it was about 290–295 ppm. Slightly over one-half the CO₂ released from fossil fuels is accounted for by the increase observed in the atmosphere; at present growth rates the quantities are doubling every 15–18 years. Atmospheric models suggest a global warming of about 2 K if the concentration were to rise to two times its pre-1900 value - enough to change the global climate in major (but largely unknown) ways. With the current rate of increase in fossil fuel use, the atmospheric concentration should reach these levels by about 2030. A shift to coal as a replacement for oil and gas gives more carbon dioxide per unit of energy; thus if energy growth continues with a concurrent shift toward coal, high concentrations can be reached somewhat earlier. Even projections with very heavy reliance on non-fossil energy (Neihaus) after 2000 show atmospheric carbon dioxide concentrations reaching 475 ppm.First presented to the symposium, Coal Science and our National Expectations, Annual Meeting of the American Association for the Advancement of Science, Boston, Massachusetts, February 20, 1976.  相似文献   

Fluorine in meteorites     

Ralph O. Allen  Patrick J. Clark 《Geochimica et cosmochimica acta》1977,41(5):581-585

Microanalysis using a resonant nuclear reaction was used to measure F concentrations in USGS standard rocks and 21 meteorites. The F appears to be a moderately depleted element, but there were significant variations within each sample. Measurements on separated metal phases suggest that about 20% of meteoritic F is in the metal or in a phase closely associated with it. Simultaneous measurements of F, Mg, Na, Al and Si in the non-magnetic fractions of meteorites suggest plagioclase as a F containing phase.  相似文献