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排序方式: 共有790条查询结果,搜索用时 31 毫秒
71.
Andreas Fries Rütger Rollenbeck Fabian Bayer Victor Gonzalez Fernando Oñate-Valivieso Thorsten Peters Jörg Bendix 《Meteorology and Atmospheric Physics》2014,126(1-2):13-29
The precise estimation of precipitation quantities in tropical mountain regions is in great demand by ecological and hydrological studies, due to the heterogeneity of the rainfall distribution and the lack of meteorological station data. This study uses radar images and ground station data to provide the required high-resolution precipitation maps. Also wind data are taken into account, due to its influence on the precipitation formation and to demonstrate the relation between synoptic wind, topography and the precipitation distribution inside small mountain valleys. The study analyses the rainfall distribution and amounts of 4 days inside the San Francisco Valley, a small catchment in the tropical Andes of southern Ecuador, representing different seasons and the typical atmospheric flows, which are correlated to the annual precipitation map. The results show that the rainfall distribution and amounts are generally defined by the wind direction and velocity, besides the topographic location in relation to the main barriers and pathways. The dominant wind direction causes a division of the catchment in a wetter eastern and a dryer western part. Moreover, the annual seasons are reversed; the main rainy season for the eastern part occurs between June and August, while the western part reaches the precipitation maximum between January and March. This may have influence on the species composition at the different slopes and the annual hydrological cycle inside the catchment. 相似文献
72.
73.
Two porphyry Cu-Mo prospects in northern Sonora, Mexico (Fortuna del Cobre and Los Humos) located within the southwestern North American porphyry province have been dated in order to constrain the timing of crystallization and mineralization of these ore deposits. In Fortuna del Cobre, the pre-mineralization granodiorite porphyry yielded an U-Pb zircon age of 76.5?±?2.3 Ma, whereas two samples from the ore-bearing quartz feldespathic porphyry were dated at 74.6?±?1.3 and 75.0?±?1.4 Ma. Four molybdenite samples from Los Humos porphyry Cu prospect yielded a weighted average Re-Os age of 73.5?±?0.2 Ma, whereas two samples from the ore-bearing quartz monzonite porphyry gave U-Pb zircon ages of 74.4?±?1.1 and 74.5?±?1.3 Ma, showing a Late Cretaceous age for the emplacement of this ore deposit. The results indicate that Laramide porphyry Cu mineralization of Late Cretaceous age is not restricted to northern Arizona as previously thought and provide evidence for the definition of NS trending metallogenic belts that are parallel to the paleo-trench. Porphyry copper mineralization follows the inland migration trend of the magmatic arc as a result of the Farallon slab flattening during the Laramide orogeny. 相似文献
74.
Julia Suso Pere Blay Almudena Robert Victor Reglero Chris J. Eyles 《Astrophysics and Space Science》2001,276(1):299-309
LEGRI has been operating successfully on MINISAT-01 since its switch-on the 22nd of May 1997. HouseKeeping (HK) data have been continuously receivedfor nearly two years by LEGRI SOC in Valencia, and subsequently checked on adaily basis and then stored for long term monitoring analysis.LEGRI HouseKeeping data include three critical operating parameters:temperature, power and polarisation voltages. Six temperature sensors arespread over the different LEGRI units: Detector Unit, Data Processing Unit,High Voltage Unit and Star Sensor. Voltages are measured at eight differentpoints. Detector Unit temperature and polarisation voltage are thecritical parameters for LEGRI operation. Solid state detectors aresensitive to changes not only in polarisation but also in temperature.Around one and a half million of measurements for each of the HK fourteen parameters have been recorded and analysed. The data show a very remarkablestability, within the expected margins, and the averages are very close to theoptimal design values. Special attention has been paid to the detectorpolarisation voltages analysis with a mean value of 286 ± 2 V when the detectors are operating. Thermal control over all the LEGRI units shows a remarkable stability in their temperatures.On the detector plane a mean value of T
det = 13 ± 2 °C has been found.We can therefore conclude that LEGRI as a system has been operating withinits optimal design conditions. We also want to point out the excellentperformance of the MINISAT-01 thermal control system. 相似文献
75.
Victor L. Vinograd Benjamin P. Burton Neil L. Allan 《Geochimica et cosmochimica acta》2007,71(4):974-983
Thermodynamic mixing properties and subsolidus phase relations of the rhombohedral carbonate system, (1 − x) · CaCO3 − x · MgCO3, were modelled in the temperature range of 623-2023 K with static structure energy calculations based on well-parameterised empirical interatomic potentials. Relaxed static structure energies of a large set of randomly varied structures in a 4 × 4 × 1 supercell of calcite (a = 19.952 Å, c = 17.061 Å) were calculated with the General Utility Lattice Program (GULP). These energies were cluster expanded in a basis set of 12 pair-wise effective interactions. Temperature-dependent enthalpies of mixing were calculated by the Monte Carlo method. Free energies of mixing were obtained by thermodynamic integration of the Monte Carlo results. The calculated phase diagram is in good agreement with experimental phase boundaries. 相似文献
76.
Lapperre Rimbaud E. Bense Victor F. Kasse Cornelis van Balen Ronald T. 《Hydrogeology Journal》2022,30(4):1233-1257
Hydrogeology Journal - Faults in the Roer Valley Rift System (Netherlands, Belgium, and Germany) act as barriers to lateral groundwater flow in unconsolidated sedimentary aquifers. This causes a... 相似文献
77.
Ayugi Brian Shilenje Zablon Weku Babaousmail Hassen Lim Kam Sian Kenny T. C. Mumo Richard Dike Victor Nnamdi Iyakaremye Vedaste Chehbouni Abdelghani Ongoma Victor 《Natural Hazards》2022,113(2):1151-1176
Natural Hazards - The ongoing global warming has caused unprecedented changes in the climate system, leading to an increase in the intensity and frequency of weather and climate extremes. This... 相似文献
78.
Xavier Bruna Catarino Egydio-Silva Marcos Sadowski Georg Robert de Assis Silva Bruno Takara Victor Junji 《Geotechnical and Geological Engineering》2022,40(3):1345-1361
Geotechnical and Geological Engineering - To optimize the prediction of structural geological conditions in the underground as of data collected at the surface, due to the usual great uncertainties... 相似文献
79.
Anastassia M. Makarieva Victor G. Gorshkov Bai-Lian Li 《Theoretical and Applied Climatology》2013,111(1-2):79-96
Using a robust global precipitation database, we analyze coast-to-interior seasonal precipitation distributions over the world’s major forest regions. We find that the active functioning of boreal forests in summer is associated with an intense ocean-to-land moisture transport, which declines in winter when forest functioning is minimal. This seasonal switch manifests itself as a change in the exponential scale length of precipitation distribution, which exceeds 15?×?103 km in summer but decreases to (3–4)?×?103 km in winter. In equatorial rainforests, which are photosynthetically active throughout the year, annual precipitation remains approximately constant, while the coefficient of variation of monthly precipitation significantly declines toward the continent interior. Precipitation over forest during the periods of active forest functioning is always higher than over the adjacent ocean. Such precipitation patterns support the biotic pump concept according to which forest cover drives the ocean-to-land atmospheric moisture transport on a continental scale. 相似文献
80.