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541.
It is shown that Titan's surface and plausible atmospheric thermal opacity sources—gaseous N2, CH4, and H2, CH4 cloud, and organic haze—are sufficient to match available Earth-based and Voyager observations of Titan's thermal emission spectrum. Dominant sources of thermal emission are the surface for wavelenghts λ ? 1 cm, atmospheric N2 for 1 cm ? λ ? 200 μm,, condensed and gaseous CH4 for 200 μm ? λ ? 20 μm, and molecular bands and organic haze for λ ? 20 μm. Matching computed spectra to the observed Voyager IRIS spectra at 7.3 and 52.7° emission angles yields the following abundances and locations of opacity sources: CH4 clouds: 0.1 g cm? at a planetocentric radius of 2610–2625 km, 0.3 g cm?2 at 2590–2610 km, total 0.4 ± 0.1 g cm–2 above 2590 km; organic haze: above 2750 km; tropospheric H2: 0.3 ± 0.1 mol%. This is the first quantitative estimate of the column density of condensed methane (or CH4/C2H6) on Titan. Maximum transparency in the middle to far IR occurs at 19 μm where the atmospheric vertical absorption optical depth is A particle radius in the upper portion of the CH4 cloud is indicated by the apparent absence of scattering effects. 相似文献
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Carl B. Agee 《Physics of the Earth and Planetary Interiors》1997,100(1-4):41-47
Melting temperatures of the silicate fraction of the Allende CV3 meteorite, at upper mantle pressures, are several hundred degrees lower than that of fertile peridotite xenoliths or ‘pyrolite’. If the Earth accreted from material similar to chondrites, then deep mantle melting could have occurred with a relatively modest heat budget. It is concluded that initial chemical composition is an important variable in realistic magma ocean models. 相似文献
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A Landscape Ecology Approach to Assessing Development Impacts in the Tropics: A Geothermal Energy Example in Hawaii 总被引:1,自引:0,他引:1
Jerry A. Griffith Carl C. Trettin & Robert V. O'Neill 《Singapore journal of tropical geography》2002,23(1):1-22
Geographic information systems (GIS) are increasingly being used in environmental impact assessments (EIA) because GIS is useful for analysing spatial impacts of various development scenarios. Spatially representing these impacts provides another tool for landscape ecology in environmental and geographical investigations by facilitating analysis of the effects of landscape pattern on ecological processes and examining change over time. Landscape ecological principles are applied in this study to a hypothetical geothermal development project on the Island of Hawaii. Some common landscape pattern metrics were used to analyse dispersed versus condensed development scenarios and their effect on landscape pattern. Indices of fragmentation and patch shape did not appreciably change with additional development. The amount of forest to open edge, however, greatly increased with the dispersed development scenario. In addition, landscape metrics showed that a human disturbance had a greater simplifying effect on patch shape and also increased fragmentation than a natural disturbance. The use of these landscape pattern metrics can advance the methodology of applying GIS to EIA. 相似文献
546.
The subsurface structure of Hagia Sophia, one of the oldest sacred monuments in the world built between 532–537 under the reign of Justinian in today's Istanbul, has been investigated by using two relative LaCoste-Romberg gravimeters in order to detect hidden cavities which have also served as earthquake dampers in similar constructions. On the building's ground floor a grid of 100 points with a grid size of about 4.m was measured. The mean gravimetric point error was ± 3.10–8 ms–2. The result of the examination is that cavities were not detected in the inner central part of Hagia Sophia with a larger diameter than 8.m down to a depth of about 20.m, and Hagia Sophia's foundation was found to be a slope of natural rock with a downward inclination to the East that has a small crest symmetrical to the building's East-West axis. 相似文献
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G. de Vaucouleurs J. Blunck M. Davies A. Dollfus I.K. Koval G.P. Kuiper H. Masursky S. Miyamoto V.I. Moroz Carl Sagan Bradford Smith 《Icarus》1975,26(1):85-98
A new nomenclature for Martian regions and topographic features uncovered by Mariner 9, as officially adopted by the International Astronomical Union, is described. About 180 craters, generally of diameters >100 km, have been named, as well as 13 classes of topographic features designated catena, chasma, dorsum, fossa, labyrinthus, mensa, mons, patera, planitia, planum, tholus, vallis, and vastitas. In addition seven craters and the Kepler Dorsum are named on Phobos, and two craters on Deimos. Coordinates and maps of each named features are displayed. 相似文献
550.