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81.
David Sanz Juan José Gómez-Alday Santiago Castaño Angel Moratalla Jorge De las Heras Pedro Emilio Martínez-Alfaro 《Hydrogeology Journal》2009,17(6):1375-1391
The Mancha Oriental System (MOS) has a surface area of 7,260 km2, making it one of the largest carbonate aquifer systems in Spain. The system sustains about 1,000 km2 of irrigated crops and supplies groundwater to 275,000 inhabitants. The economic transformation brought about by the development of extensive irrigated cropland has led to a water-balance disequilibrium of about 75 million m3/year. This input–output deficit has negative consequences in the quantity and quality of the available resources, in the river–aquifer relationship, and in the associated ecosystems as well. To understand the hydrogeological behaviour of the system, it is necessary to design a conceptual model. Further, the conceptualisation of a groundwater flow system is a requirement of the European Water Framework Directive for the characterisation of groundwater bodies. The robustness of the conceptual model depends heavily on the user capability of representing the real system. In this work, a multidisciplinary approach has been used to represent the three-dimensional geological framework and the groundwater flow conceptualisation of the MOS. Data management and three-dimensional visualisation have been carried out by means of geographical information system (GIS) tools and software for contouring and three-dimensional surface mapping. 相似文献
82.
83.
M. deCastro M. Gómez-Gesteira I. Alvarez J.L.G. Gesteira 《Continental Shelf Research》2009,29(8):1053-1059
The warming trend observed during the last decades in the Bay of Biscay is put within the context of sea surface temperature (SST) changes observed in the area since 1854. Macroscopically, two consecutive warming–cooling cycles were detected during this period of time: cooling from 1867 to 1910; warming from 1910 to 1945; cooling from 1945 to 1974; and warming from 1974 to nowadays. Warming rates of 0.17 and 0.22 °C per decade were measured during the warming sub-periods and cooling rates of ?0.14 and ?0.10 °C per decade were measured during the cooling sub-periods. The present warming period is on the same order of magnitude although slightly more intense than the one observed from 1910 to 1945, which is consistent with previous analysis carried for the North Atlantic. Finally, the thermal amplitude defined as the difference between the maximum and minimum annual values has increased since 1974 at a rate of 0.06 °C per decade due to the different increasing rates of the maximum (0.26 °C per decade) and minimum (0.20 °C per decade) SSTs. 相似文献
84.
I. M. Chertok 《Astronomy Reports》2006,50(1):68-78
Data obtained with the EIT UV telescope and LASCO coronagraph of the SOHO satellite are used to analyze large-scale solar disturbances associated with a series of major flares and coronal mass ejections that occurred in the late decline phase of cycle 23, on November 3–10, 2004, and gave rise to strong geomagnetic storms. Derotated fixed-base difference heliograms taken in the 195 Å coronal channel at 12-min intervals and in the various-temperature 171, 195, 284, and 304 Å channels at 6-h intervals indicate that these disturbances were global and homologous; i.e., they had similar characteristics and affected the same structures. Almost all of the nine events of this series included two recurrent systems of large-scale dimmings (regions of reduced intensity with lifetimes of 10–15 h): (a) transequatorial dimmings connecting a northern near-equatorial eruption center with a southern active region and (b) northern dimmings covering a large sector between two coronal holes. In this northern sector, coronal waves (brightenings propagated from the eruption center at speeds of several hundred km/s) were observed ahead of the expanding dimmings. The brightest, central part of the halo-type coronal mass ejection in each event corresponded to the northern dimming system. The properties of the dimmings and coronal waves and the relationship between them are discussed on the basis of the results obtained. We find that the eruption of large coronal mass ejections involves structures of the global solar magnetosphere with spatial scales far exceeding the sizes of active regions and normal activity complexes. 相似文献
85.
A problem of estimation of shock wave attenuation in an obstacle under an explosion of a high-energy material (explosive) charge on its surface is considered. An algorithm for its solution is proposed using the analytical and semiempirical dependences generally recognized in explosion physics. 相似文献
86.
I. A. Klimishin 《Astrophysics and Space Science》1973,22(1):3-12
The regularities of strong thermal waves moving in non-uniform media are considered in some detail. The application of thermal wave theory to Nova outburst interpretation is discussed. 相似文献
87.
The investigation of the bottom of Lake Baikal carried out during the 2008 summer season by means of Mir manned deep-submergence
vehicles resulted in the recovery of a series of sediments, ferruginous crusts, and peculiar mineralized tubes several centimeters
high and up to 2–6 cm in diameter. According to the scanning electron investigation, these formations consist mainly of the
enclosing sediment particles and biogcnie silica cemented by iron and minor manganese hydroxides. The chemical composition
of the tubes is similar to both that of the enclosing sediments and slightly ferruginous crusts and nodules, but the tubes
and crusts are somewhat richer relative to the sediments in some microelements, namely, arsenic, cadmium, and uranium. In
general, the structure and composition of these tubes reminds one of the worm tubes common in the sediments of a number of
seas. The investigation of the rare earth elements in some samples or ferruginous formations and sediments revealed a positive
europium anomaly, which might be related to either the composition of the surrounding continental magmatic rocks or to the
influence of hypothetical hydrothermal solutions. 相似文献
88.
A. N. Opanasenko N. V. Opanasenko Yu. G. Shkuratov V. G. Kaidash Yu. I. Velikodskii V. V. Korokhin 《Kinematics and Physics of Celestial Bodies》2011,27(1):38-41
Polarimetric observations of the moon have been carried out at λeff = 0.48 and 0.63 μm using the 50 cm telescope of the Maidanak (Middle Asia) observatory. Imaging has been performed using
a Canon-350D camera with a CMOS array and rotating polaroid. The investigation covered the north-western part of the lunar
disk comprising the northern part of Ocean Procellarum and obtained the images representing the albedo, polarization degree, color index, and polarimetric color ratio at a phase
angle of 96°. It is the first time that the latter parameter has been imaged with a resolution of approximately 1 km. Its
pattern has proved to resemble that of the color index, although some important differences can be seen. This shows that spectropolarimetric
observations of the moon can give new information on the composition and optical properties of the lunar regolith. 相似文献
89.
R.M.C. Lopes E.R. Stofan J. Radebaugh G. Mitri R.L. Kirk J.I. Lunine R. Lorenz L. Wye R.J. Ollerenshaw A. LeGall R. West P. Callahan P. Valora the Cassini RADAR Team 《Icarus》2010,205(2):540-558
The Cassini Titan Radar Mapper is providing an unprecedented view of Titan’s surface geology. Here we use Synthetic Aperture Radar (SAR) image swaths (Ta-T30) obtained from October 2004 to December 2007 to infer the geologic processes that have shaped Titan’s surface. These SAR swaths cover about 20% of the surface, at a spatial resolution ranging from ∼350 m to ∼2 km. The SAR data are distributed over a wide latitudinal and longitudinal range, enabling some conclusions to be drawn about the global distribution of processes. They reveal a geologically complex surface that has been modified by all the major geologic processes seen on Earth - volcanism, tectonism, impact cratering, and erosion and deposition by fluvial and aeolian activity. In this paper, we map geomorphological units from SAR data and analyze their areal distribution and relative ages of modification in order to infer the geologic evolution of Titan’s surface. We find that dunes and hummocky and mountainous terrains are more widespread than lakes, putative cryovolcanic features, mottled plains, and craters and crateriform structures that may be due to impact. Undifferentiated plains are the largest areal unit; their origin is uncertain. In terms of latitudinal distribution, dunes and hummocky and mountainous terrains are located mostly at low latitudes (less than 30°), with no dunes being present above 60°. Channels formed by fluvial activity are present at all latitudes, but lakes are at high latitudes only. Crateriform structures that may have been formed by impact appear to be uniformly distributed with latitude, but the well-preserved impact craters are all located at low latitudes, possibly indicating that more resurfacing has occurred at higher latitudes. Cryovolcanic features are not ubiquitous, and are mostly located between 30° and 60° north. We examine temporal relationships between units wherever possible, and conclude that aeolian and fluvial/pluvial/lacustrine processes are the most recent, while tectonic processes that led to the formation of mountains and Xanadu are likely the most ancient. 相似文献
90.
Normal albedos of thirteen lunar regions are determined at five wavelengths between 4000 and 8000 Å. The deduced values agree with those of the previous investigators except those given by Gehrelset al. (1964) and Van Diggelen (1965). They increase monotonically with the wavelength. At the shortest wavelength, a slight enhancement is detected for most of the regions observed. 相似文献