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951.
The global distribution of the ground-level temperature variance and its long-term variations have been investigated on the basis of the monthly mean temperature anomalies, obtained from ground-based and sea-borne meteorological observations from 1896 to 1990. Particular characteristics of the large-scale structure of the temperature variance have been found. There are three pronounced maxima in the global distribution of the temperature variance: in Central Siberia (60°75°N and 70° 120°E), North America (60°75°N and –170°–120°E) and the Antarctica (50°65°S and –60°10°E, where and are the geographic latitude and longitude, respectively) and there are two minima: over the Atlantic and Pacific Ocean areas. The minimum over the Pacific is not as pronounced, as over the Atlantic. The spatial pattern of the ground-level temperature variance is, on the whole, stable, the positions of the zones of extrema remaining practically unchanged over a long time interval. These results indirectly corroborate the mechanism of solar impact on the properties of the low atmosphere by the modulation of the flux of galactic cosmic rays. The mechanism accounts for the spatial distribution of the temperature variance as a result of combined effect of solar activity and ocean. Long-term variations of the Siberian maximum of the ground-level temperature variance agree with the changing duration of the sunspot cycle, in contrast to the North American maximum. 相似文献
952.
本文主要阐述了以下问题:1.亚欧大陆地理内心含义与研究目的;2.以地图为基准的大陆内心测算方法;3.测算结果精度分析;4.内心辐射区的多层结构;5.内心地与内心区旅游开发环境。 相似文献
953.
RQD研究的几个理论问题 总被引:1,自引:0,他引:1
岩石质量指标RQD是岩体工程分类和稳定性评价中最常用的定量描述参数。30多年来,RQD的概念和理论研究有了重大进展。本文对源于工程应用的几个RQD理论问题进行了评述,同时提出了一些新的研究思路。 相似文献
954.
955.
运用双层地基模型的线弹性有限元程序对不同类型水泥土搅拌桩复合地基的沉降进行计算,分析了水泥土搅拌桩的桩长、置换率、桩身刚度对地基沉降的影响,同此确定了搅拌桩的有效桩长、最优置换率、最优桩身刚度。 相似文献
956.
The turbulence closure in atmospheric boundary-layer modelling utilizing Reynolds Averaged Navier–Stokes (RANS) equations
at mesoscale as well as at local scale is lacking today a common approach. The standard kɛ model, although it has been successful for local scale problems especially in neutral conditions, is deficient for mesoscale
flows without modifications. The k–ɛ model is re-examined and a new general approach in developing two-equation turbulence models is proposed with the aim of
improving their reliability and consequently their range of applicability. This exercise has led to the replacement of the
ɛ-transport equation by the transport equation for the turbulence inverse length scale (wavenumber). The present version of
the model is restricted to neutrally stratified flows but applicable to both local scale and mesoscale flows. The model capabilities
are demonstrated by application to a series of one-dimensional planetary boundary-layer problems and a two-dimensional flow
over a square obstacle. For those applications, the present model gave considerably better results than the standard k–ɛ model. 相似文献
957.
本文介绍了描述等角投影变换的Dirichlet模型和用加权残值法求解该模型的一般原理和方法,并给出了应用上述方法所获得的某些等角投影变换的数值公式。文章最后指出,由于应用数值方法,有可能形成一门新的学科,即计算地图投影学。 相似文献
958.
Two models have been developed by applying conditions of continuity between the roughness sublayer and the top of vegetation
canopy having constant foliage distribution. Massman's cosh-type of wind profile and Albini's exponential wind profile have
been used to derive expressions for shear stress, displacement height and roughness length in analytical forms. The computed
results compared with those of Massman models (1987, 1997) show similarity with the present models. 相似文献
959.
Diversity and Distribution of the Bryozoa along Underwater Cliffs in the Adriatic Sea with Special Reference to Thermal Regime 总被引:2,自引:0,他引:2
Abstract. The diversity and distribution of bryozoans have been surveyed at two localities, Cape Struga on Lastovo Island (South Adriatic) and Cape Šilo on Prvić Island near Senj (North Adriatic), with similar characteristics of topography and exposure but markedly different sea temperature conditions. Continuous measurements over one year have shown that temperature conditions differ in two aspects. First, the annual range of temperature is much larger in the North. Second, in the South during summer, marine life within the thermocline layer is exposed to large high-frequency temperature oscillations, partly due to an internal diurnal tide, a phenomenon recorded for the first time in the Adriatic. Altogether, 78 species have been recorded, 57 in Lastovo and 50 in Prvić, and 29 in both localities. The comparison of mean zooid lengths of 14 bryozoan species occurring at both localities indicates no consistent difference in zooid size between northern and southern sites. Seventeen bryozoan species have been recorded in the Eastern Adriatic Sea for the first time. 相似文献
960.