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31.
Space monitoring of Aral Sea degradation 总被引：1，自引：0，他引：1
The results of remote sensing survey of the Aral Sea in its degradation period are given. Satellite images are used to map
shoreline retreat from 1961 to 2008 and to measure the decrease in the area. Seasonal variations in shoreline and water area
are identified, suggesting seasonal level variations and correlating well with data of satellite altimetry surveys of sea
level. Observations covered surge phenomena, seasonal dynamics of landscapes, and the seasonal salinization rhythm in coastal
territories with the subsequent formation and weathering of salt crusts. The character of river runoff input into the Great
Sea resulting from overbank flooding in artificial water bodies in the Amu Darya delta is identified. 相似文献
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A paper describing activities of the Laboratory of Remote Sensing Methods at Moscow University presents a chronology of the Laboratory's efforts to improve sensor capabilities for acquiring remote sensing data and to develop more effective image processing techniques. Among the accomplishments cited are early advances in sensor system design and photochemical processing in conjunction with “Salyut” orbital station activities, multispectral imaging experiments in conjunction with high-resolution space photography from the Soyuz-12 (1973) and Soyuz-22 (1976) missions, testing of the first high-resolution Soviet (“Fragment”) scanner imagery (1984), and ongoing work in digital and applied image processing. Translated from: Vestnik Moskovsskogo Universiteta, geografiya, 1987, No. 2, pp. 27-31. 相似文献
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The lithology, sedimentation conditions, tectonic evolution features, and mineralization of molassoid complexes in southwestern Ghana that fill the Tarkwa and Bui basins located within the Birrimian Paleoproterozoic orogenic belt are described on the basis of an analysis of published and our own data. The formation of these sediments in geodynamic conditions of pull-apart basins is described. The deposits of the Tarkwa group are compared with the Archean Timiskaming group of the Superior Province and similar younger complexes. The Tarkwa group is considered as the Paleoproterozoic equivalent of molasse-like complexes that formed at the last stage of accretion orogens of different ages in pull-apart structures. 相似文献
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The paper considers the major geographic features of the modern Huang He delta, which ranks among the most rapidly varying in the world. The structure of the hydrographic network and the combination of the natural and anthropogenic geosystems of the delta are characterized. The major external riverine and marine, as well as local anthropogenic factors that have affected the development of the Huang He delta in the recent half century are identified. The regularities of the jump-like development of the Huang He delta in the XIX–early XXI centuries are considered. Special attention is paid to the development of the delta after the artificial redistribution of flow in its boundaries in 1996. Satellite images and methods of their interpretation improved by the authors were used. The trends in Huang He delta development are shown to have changed since the last quarter of the XX century under the effect of an abrupt decrease in river sediment load and the growing impact of marine factors. The active progradation of the delta into the sea slowed down significantly, accompanied by erosion and retreat in many segments of its coastline. Huang He delta was used to establish the conditions of changes in the development trends of other deltas under the effect of changes in the climate and economic activity. 相似文献
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V. I. Kravtsova 《地理信息系统科学与遥感》2013,50(3):169-178
This paper outlines some principles believed necessary for the establishment of integrated collections of remote sensing imagery, including, at the national level, a unified state image repository for the USSR. A multi-criterion classification of imagery is introduced, which provides a framework for structuring such a repository, and a number of measures for evaluating the utility of imagery within it are described. One of the latter is “geographic” resolution (levels of image detail), which provides a relatively straightforward indication of the type of geographic information embedded within particular types of remote sensing imagery. Translated by Jay K. Mitchell, PlanEcon, Inc., Washington, DC 20005 from: Vestnik Moskovskogo Universiteta, geografiya, 1988, No. 6, pp. 53-62. 相似文献
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Speckle-interferometric observations of FU Ori are performed with the 6-m telescope of the Special Astrophysical Observatory with 600/40 nm and 800/100 nm (central bandwidth/halfwidth) filters. The companion star FU Ori S that was recently discovered at λ >-1.25µm was recorded in observations with the λ/Δλ==800/100 nm filter. The positional parameters and magnitude difference of the companion in the filter considered are found to be θ = (163.9 ± 1.0)°, ρ = (0.493 ± 0.007)″, Δm = 3.96 ± 0.28. An analysis of the spectral energy distribution of the companion implies that for the extinction A V toward FU Ori to be greater than about 1.6 m , i.e., the minimum value required by the available models of the fuor, the spectral type of the companion star must be no later than K3. The reliability of this conclusion and the possible ways for obtaining more accurate estimates of A V are discussed. 相似文献
39.
We analyze the spectra of DR Tau in the wavelength range 1200 to 3100 Å obtained with the GHRS and STIS spectrographs from the Hubble Space Telescope. The profiles for the C IV 1550 and He II 1640 emission lines and for the absorption features of some lines indicate that matter falls to the star at a velocity ～300 km s?1. At the same time, absorption features were detected in the blue wings of the N I, Mg I, Fe II, Mg II, C II, and Si II lines, suggesting mass outflow at a velocity up to 400 km s?1. The C II, Si II, and Al II intercombination lines exhibit symmetric profiles whose peaks have the same radial velocity as the star. This is also true for the emission features of the Fe II and H2 lines. We believe that stellar activity is attributable to disk accretion of circumstellar matter, with matter reaching the star mainly through the disk and the boundary layer. At the time of observations, the accretion luminosity was Lac ? 2L⊙ at an accretion rate ?10?7M⊙ yr?1. Concurrently, a small (<10%) fraction of matter falls to the star along magnetospheric magnetic field lines from a height ～R*. Within a region of size ?3.5R*, the disk atmosphere has a thickness ～0.1R* and a temperature ?1.5 × 104 K. We assume that disk rotation in this region significantly differs from Keplerian rotation. The molecular hydrogen lines are formed in the disk at a distance <1.4 AU from the star. Accretion is accompanied by mass outflow from the accretion-disk surface. In a region of size <10R*, the wind gas has a temperature ～7000 K, but at the same time, almost all iron is singly ionized by H I L α photons from inner disk regions. Where the warm-wind velocity reaches ?400 km s?1, the gas moves at an angle of no less than 30° to the disk plane. We found no evidence of regions with a temperature above 104 K in the wind and leave open the question of whether there is outflow in the H2 line formation region. According to our estimate, the star has the following set of parameters: M* ? 0.9M⊙, R* ? 1.8R⊙, L* ? 0.9L⊙, and \(A_V \simeq 0\mathop .\limits^m 9\). The inclination i of the disk axis to the line of sight cannot be very small; however, i≤60°. 相似文献
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