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361.
362.
Summary. Examples of core motions which generate the observed secular variation field – as given by various models for 1970 and 1980 – from the main field have been computed in the frozen flux approximation, assuming that the spectrum of the motion is of low degree and decreases with wave-number. No mode of degree > 4 in the expansion of the motion can be derived with any degree of confidence. Among the low degree modes, some appear to be stable (they come out with the same magnitude whatever the inversion scheme used). The flow made of these stable modes is then examined. An outstanding feature of the flow is the body westward drift. But it seems necessary, if one looks for such a regular flow, to consider both toroïdal and poloïdal components, which would imply upwelling and down-welling in the upper layers of the core. The toroïdal part of the flow appears to be enhanced by the 1969 impulse, although its geometry is nearly unchanged. On the contrary the geometry of the computed poloïdal part is different in 1980 and in 1970; 相似文献
363.
A. Mazure P. Katgert R. Den Hartog A. Biviano P. Dubath E. Escalera P. Focardi D. Gerbal G. Giuricin B. Jones O. Le Fèvre M. Moles J. Perea G. Rhee 《Astrophysics》1995,38(4):367-369
A statistically reliable distribution of velocity dispersions free from biases and systematic errors for a sample of ACO clusters is obtained. This distribution is compared with other data and model predictions.Published in Astrofizika, Vol. 38, No. 4, pp. 654–658, October–December, 1995. 相似文献
364.
Summary. From 1883 to 1901 magnetic elements were continuously recorded at the French Saint-Maur observatory. From 1893 to 1895, Earth potentials along two 15 km long orthogonal lines were also recorded. Moreover, from 1884 to 1885, Blavier,'Ingénieur des Télégraphes', used several some hundred kilométre long telegraphic lines to measure and record Earth potentials. Using this set of data we will study the daily variations of the telluric and magnetic fields and the way according to which these two fields are correlated.
The observed magnetotelluric tensor is antisymmétric when the long telluric lines are considered. It is not the case for the short lines. But, making use of a correction derived from the formalism developed by Le Mouel & Menvielle in the static distortion approximation, one can derive an impedance whose phase is equal to the phase of the impedance derived from the long line data. 相似文献
The observed magnetotelluric tensor is antisymmétric when the long telluric lines are considered. It is not the case for the short lines. But, making use of a correction derived from the formalism developed by Le Mouel & Menvielle in the static distortion approximation, one can derive an impedance whose phase is equal to the phase of the impedance derived from the long line data. 相似文献
365.
366.
基于1973—2015年间的全球综合无线电探空资料(IGRA),采用总体理查逊数(Bulk Richardson Number)方法,分析了北极扬马延岛43年间的大气边界层高度变化特征,并对其多年月均大气边界层高度变化以及年均大气边界层高度变化进行深入分析探讨。结果显示,扬马延岛白天对流边界层高度高于夜晚稳定边界层高度,夏季多年月均大气边界层高度远低于冬春季节的高度,夏季平均高度仅为262 m,而冬春季节高度在600 m附近。大气边界层高度的变化与地面相对湿度的变化呈现较好的反相关关系。由于受到墨西哥湾暖流的影响,岛屿全年温差较小,夏季的相对湿度较大,导致潜热通量较多,抑制了边界层内的对流过程,造成夏季大气边界层高度较低。此外,其年均高度在1973—1988年间出现波动下降,而后在1988—1995年快速上升,最后于1995—2015年间变化平稳。 相似文献
367.
鄂尔多斯盆地东北缘晚古生代陆表海含煤岩系层序地层研究 总被引:4,自引:0,他引:4
通过区域不整合面、沉积体系转换面、构造应力场转换面和水上暴露面等层序界面的识别,对研究区进行层序地层划分,指出鄂尔多斯盆地东北缘晚古生代陆表海含煤岩系发育7个三级层序。在此基础上,认为陆表海层序仍然具有“三元”结构,由低位体系域、海侵体系域和高位体系域组成。在盆地北部发育的多期河道砂岩具有低位体系域的下切谷充填特点——面状充填,如晋祠砂岩、桥头砂岩以及北岔沟砂岩等。煤层在层序格架中的定位与海平面变化的转换时期有关,主要发育在陆表海环境的海侵体系域下部以及陆相环境的高位体系域上部。 相似文献
368.
This article explores the impacts of floods on the economy, environment, and society and tries to clarify the rural community’s
coping mechanism to flood disasters in Central Viet Nam. It focuses on the social aspects of flood risk perception that shapes
the responses to floods. The research findings revealed that flooding is an essential element for a coastal population, whose
livelihood depend on productive functions of cyclical floods. The findings also revealed that floods, causing losses and damages,
often inhibited economic development. The surveyed communities appeared to have evolved coping mechanisms to reduce the negative
impacts of the floods, yet these coping mechanisms are under pressure due to environmental degradation. Integrated flood risk
management is considered as a suitable paradigm for coping with flood disasters.
相似文献
Phong TranEmail: |
369.
The Eocene Trihueco Formation is one of the best exposed successions of the Arauco Basin in Chile. It represents a period of marine regression and transgression of second-order duration, during which barrier island complexes developed on a muddy shelf. The strata are arranged in classical shoaling-upward parasequences of shoreface and beach facies capped by coal-bearing, back-barrier lagoon deposits. These fourth-order cycles are superimposed upon third-order cycles which caused landward and seaward shifts of the coastal facies belts. The final, punctuated rise in sea level is represented by shelf mudrocks with transgressive incised shoreface sandstones. Relative sea-level oscillations as revealed in the stratigraphy of the Trihueco Formation show a reasonable correlation with published Eocene eustatic curves. 相似文献
370.