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311.
R. G. Bill Jr. E. Chen R. A. Sutherland J. F. Bartholic 《Boundary-Layer Meteorology》1979,16(1):23-33
A steady-state, two-dimensional numerical model is used to simulate air temperatures and humidity downwind of a lake at night. Thermal effects of the lake were modelled for the case of moderate and low surface winds under the cold-air advective conditions that occur following the passage of a cold front. Surface temperatures were found to be in good agreement with observations. A comparison of model results with thermal imagery indicated the model successfully predicts the downwind distance for which thermal effects due to the lake are significant. 相似文献
312.
Tamarix nabkha is one of the most widespread nabkhas,distributing in the arid region of China.Based on the observations outdoors and the simulation experiments in laboratories,analysis in this paper refers to the biological geomorphologic features and growth process of Tamarix nabkhas in the middle and lower reaches of the Hotan River,Xin- jiang.And the results indicate that the ecological type of Tamarix in the study area is a kind of Tugaic soil habitat based on the deep soil of the Populus Diversifolia f... 相似文献
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314.
An anomalous high-velocity layer at shallow crustal depths in the Narmada zone, India 总被引:2,自引:0,他引:2
The Narmada zone in central India is a zone of weakness that separates the region of Vindhyan (Meso-Neoproterozoic) deposition to the north from Gondwana (Permo-Carboniferous–lower Cretaceous) deposits to the south. The reinterpretation of analogue seismic refraction data, acquired during the early 1980s, using 2-D ray-tracing techniques reveals a basement (velocity 5.8–6.0 km s−1 ) topography suggesting that the Narmada zone, bounded by the Narmada North and Narmada South faults is a region of basement uplift. A layer of anomalously high velocity (6.5–6.7 km s−1 ) at depths between 1.5 and 9.0 km appears to be present in the entire region. Within the Narmada zone this layer occurs at shallower depths than outside the Narmada zone. At two places within the Narmada zone this layer is at a depth of about 1.5 km. This layer cannot be considered as the top of the lower crust because in this case it should have produced large positive gravity anomalies at the shallowest parts. Instead, these parts correspond to Bouguer gravity lows. Furthermore, lower crust at such shallow depths has not been reported from any other part of the Indian shield. Therefore, this layer is likely to represent the top of a high-velocity mafic body that has different thicknesses in different places. 相似文献
315.
MIL 090070陨石是2009年美国南极陨石搜寻项目(ANSMET)在南极横断山脉米勒山区(Miller Range)发现的一块月球陨石,属于斜长岩质月表角砾岩。它具有典型的碎屑结构,主要由岩屑、晶屑、玻屑和细粒基质组成。岩屑以复合斜长岩质岩屑和斜长岩岩屑为主,其次为辉长岩质斜长岩岩屑、辉长岩岩屑、辉长苏长岩岩屑、辉长岩质橄长岩岩屑和橄榄辉长岩岩屑等。晶屑有普通辉石、易变辉石、斜长石、尖晶石、石英和钛铁矿等矿物。玻屑主要为斜长石质的玻屑,呈细长或弯曲条状,多具裂纹。MIL 090070陨石的矿物组成主要为斜长石(86 vol%,An92—99)、橄榄石(6 vol%,Fo53—89)、辉石(7 vol%,En25—83Fs7—43Wo2—45),以及少量的尖晶石、钛铁矿和石英等;其中,辉石有单斜辉石和斜方辉石二种。MIL 090070陨石中橄榄石和辉石的Fe-Mn值分布明显不同于地球、火星、金星和小行星的样品,基本落在月球岩石范围。MIL 090070陨石在多期次冲击和胶结作用下,岩屑的矿物成分和粒度不断变化,岩屑类型更多样,更复杂。基于MIL 090070陨石的岩石矿物学特征、碎屑类型及结构的特征等研究,可以进一步丰富我们对月球物质的形成及月岩—月壤演化过程的认识。 相似文献
316.
Christian Betzler Jörn Fürstenau Thomas Lüdmann Christian Hübscher Sebastian Lindhorst Andreas Paul John J. G. Reijmer André W. Droxler 《Basin Research》2013,25(2):172-196
Multichannel high‐resolution seismic and multibeam data were acquired from the Maldives‐isolated carbonate platform in the Indian Ocean for a detailed characterization of the Neogene bank architecture of this edifice. The goal of the research is to decipher the controlling factors of platform evolution, with a special emphasis on sea‐level changes and changes of the oceanic currents. The stacking pattern of Lower to Middle Miocene depositional sequences, with an evolution of a ramp geometry to a flat‐topped platform, reflects variations of accommodation, which here are proposed to be primarily governed by fluctuations of relative sea level. Easterly currents during this stage of bank growth controlled an asymmetric east‐directed progradation of the bank edge. During the late middle Miocene, this system was replaced by a twofold configuration of bank development. Bank growth continued synchronously with partial bank demise and associated sediment‐drift deposition. This turnover is attributed to the onset and/or intensification of the Indian monsoon and related upwelling and occurrence of currents, locally changing environmental conditions and impinging upon the carbonate system. Mega spill over lobes, shaped by reversing currents, formed as large‐scale prograding complexes, which have previously been interpreted as deposits formed during a forced regression. On a regional scale, a complex carbonate‐platform growth can occur, with a coexistence of bank‐margin progradation and aggradation, as well as partial drowning. It is further shown that a downward shift of clinoforms and offlapping geometries in carbonate platforms are not necessarily indicative for a sea‐level driven forced regression. Findings are expected to be applicable to other examples of Cenozoic platforms in the Indo‐Pacific region. 相似文献
317.
A GIS-implemented, deterministic approach for the automated spatial evaluation of geometrical and kinematical properties of
rock slope terrains is presented. Based on spatially distributed directional information on planar geological fabrics and
DEM-derived topographic attribute data, the internal geometry of rock slopes can be characterized on a grid cell basis. For
such computations, different approaches for the analysis and regionalization of available structural directional information
applicable in specific tectonic settings are demonstrated and implemented in a GIS environment. Simple kinematical testing
procedures based on feasibility criteria can be conducted on a pixel basis to determine which failure mechanisms are likely
to occur at particular terrain locations. In combination with hydraulic and strength data on geological discontinuities, scenario-based
rock slope stability evaluations can be performed. For conceptual investigations on rock slope failure processes, a GIS-based
specification tool for a 2-D distinct element code (UDEC) was designed to operate with the GIS-encoded spatially distributed
rock slope data. The concepts of the proposed methodology for rock slope hazard assessments are demonstrated at three different
test sites in Germany. 相似文献
318.
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