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131.
Marine molluscan shells from para-type and other loclities of the Holsteinian interglaciation were dated by Th/U and the electron spin resonance (ESR) method to more than 350,000 and 370,000 yr B.P., beyond the limit of Th/U dating. The high age estimate is corroborated by a K/Ar age of 420,000 yr B.P. determined from volcanic ash near the base of the Ariendorf paleosol in the Middle Rhine valley believed to be a pedostratigraphic equivalent of the Holsteinian. Shells from the Herzeele marine unit III, an equivalent of the Wacken (Dömnitz) warm stage in northern France and subsequent to the Holsteinian, revealed ages between 300,000 and 350,000 yr B.P. A correlation of these two warm stages with marine oxygen-isotope stages 11 and 9 on the SPECMAP and CARTUNE time scales is suggested. From the benthic oxygen-isotope record one may infer that no exceptionally high global sea-level rise corresponds to the large transgressions of the Holstein Sea in northern Germany. Therefore, a significant proportion of the transgression was probably the result of an unusually large local glacial-isostatic depression caused by the extreme buildup of ice during the preceding Elster glaciation (stage 12). According to the deep-sea record, it lasted approximately 50% longer than the subsequent cold stage 10. The outstanding soil formation with Braunlehm and the well-developed thermal optimum of the Holsteinian are tentatively related to a phase of minimum sea-ice cover in the Norwegian-Greenland Sea, as deduced from long benthic carbon-isotope records from the central Atlantic. 相似文献
132.
In this 8th compilation, the following results of observations are given: 207 observed minima of 56 eclipsing binaries, 100 maxima of 21 RR Lyrae- and δ Cephei-stars, 82 results of 32 Mira stars and long period variables, and 47 results of 9 RV Tauri stars, semiregular, and irregular variables, from the years 1966 up to 1968. 相似文献
133.
The study of REE distribution in the clay fraction of sedimentary rocks from two coalfields made it possible to distinguish
several types of REE distribution, which correlate with their mineral composition. It is shown that the REE fractionation
was related to the mineral reconstruction of the primary clay fraction and some detrital minerals in the course of postsedimentary
transformations of rocks during diagenesis, early catagenesis, and beginning of late catagenesis. These transformations were
governed by several factors, such as the composition of sediments; hydrochemical features of accumulation environment; the
chemical composition, dynamics, and feeding sources of pore solutions; the porosity and permeability of sediments and rocks;
and the content of organic matter and its reaction ability. 相似文献
134.
The sodian stellerite (a zeolite) occurs as lustrous white or slightly pink, easily cleavable lamellae, filling cavities and fractures in an acid lava (andesite or rhyolite) in the cliff below S. Efisio Tower, near Capo Pula, Cagliari, Sardegna, Italy. The principal forms present are {010}, {011}, {111}. Single crystal photographs show an orthorhombic symmetry and Ammm (or Ammm) space group. An indexed X-ray diffraction powder pattern is provided. Unit cell dimensions, chemical formula, density, optical properties and thermal behaviour are given. 相似文献
135.
Summary Snow has been studied widely in hydrology for many decades whereas recent meteorological interest in snow is caused by increased
emphasis on high latitudes and wintertime in climate-change research as well as by the need to improve weather-forecast models
during these conditions. Ground-based measurements of snow properties are needed both to improve understanding of surface-atmosphere
exchange processes and to provide ground truth to new remote-sensing algorithms. This justifies a review of techniques to
measure snow in combination with establishment of criteria for the suitability of the methods for process studies. This review
assesses the state-of-art in ground-based snow-measurement techniques in the end of the 1990s in view of their accuracy, time
resolution, possibility to automate, practicality and suitability in different terrain. Methods for snow-pack water equivalent,
depth, density, growth, quality, liquid-water content and water leaving the snow pack are reviewed. Synoptic snow measurements
in Fennoscandian countries are widely varying and there is no single standard on which process-related studies can build.
A long-term, continuous monitoring of mass and energy properties of a snow cover requires a combination of point-measurement
techniques. Areally representative values of snow properties can be achieved through a combination of automatically collected
point data with repeated manual, areally covering measurements, remote-sensing data and digital elevation models, preferably
in a GIS framework.
Received August 27, 1999 相似文献
136.
Investigations in a newly constructed subsea road tunnel in the Iddefjord granite at Hvaler and test-pumping of boreholes on land indicate that a topographic or geophysical anomaly is no guarantee of a substantially transmissive fracture zone. Many prominent fracture zones appear to have depressed transmissivity due to secondary swelling-clay mineral infillings. No current geophysical technique can adequately distinguish these zones from transmissive ones. Given that siting of boreholes on the basis of geology alone can be unreliable, hydrogeologists should concentrate on quantifying the chances of a successful boring, and optimizing those chances by sensible location, favourable borehole orientation and use of artificial enhancement techniques. 相似文献
137.
E. G. Kolomyts 《Russian Meteorology and Hydrology》2008,33(7):430-440
The gradient (ordination) analysis was used to find the tendencies and the rate of changes in discrete parameters of the cycle of forest phytomasses accompanying a growing thermoarid climatic trend. The prognostic estimates of biotic regulation of the carbon cycle by forest biogeocenoses according to the HadCM3 (version A2) climatic scenarios, describing the most powerful coming global warming, are presented. 相似文献
138.
Diurnal variation of deep cloud systems over the Indian region using INSAT-1B pixel data 总被引:1,自引:0,他引:1
Summary
Among the various time scales of deep clouds, diurnal variation is found to be prominent over the tropics. The present study
examines the diurnal variation in the number and area cover associated with the cloud systems over the tropical Indian region
using INSAT-1B pixel data. Three periods, namely, April–May 1988, July–August 1988, and January–February 1989 are considered.
The dependence of diurnal characteristics on the temperature threshold, life duration and size of cloud systems, and land-sea
contrast has been explored. The diurnal characteristics of cloud systems living for more than a day have been studied for
the first time. It is shown that cloud systems exhibit strong diurnal dependence at the coldest temperature threshold used
(201 K). Also, the diurnal variation is more for larger cloud systems and for longer living systems. In general, more deep
cloud activity is found from the satellite data during the pre-dawn and early morning hours. Precipitation is enhanced during
morning to early noon hours. Further, using data from a recent field experiment, clear evidence of diurnal variation in precipitation
over the Bay of Bengal is also presented.
Received March 20, 2000/Revised October 3, 2000 相似文献
139.
B. E. Peskov A. A. Alekseeva A. E. Nikiforova 《Russian Meteorology and Hydrology》2008,33(10):644-650
The physical-synoptic principles of the automated method of summer precipitation forecasting introduced into operational prognostic practice in 2006 by the decree of the Central Methodical Commission of the Federal Service for Hydrometeorology and Environmental Monitoring (Roshydromet) are presented. Beside that, improved modifications of this method, which are automatically updated, are shown. Validation of those updates based on observational data collected in 2004 has shown improvement of all major criteria of forecasts efficiency. The performed improvement is based on the more detailed quantitative realization of mechanism of various showers formation (including heavy rainfalls). 相似文献
140.
M. R. E. Proctor 《Astronomische Nachrichten》1977,298(1):19-25
The kinematic α-effect dynamo problem is investigated in the case of an exterior perfect conductor. It is shown that certain approximate symmetries discovered in the numerical analysis of ROBERTS (1972) are exact for this case. As an illustration, an exact solution is given in a cylindrical geometry, where the equations can be written in terms of one variable. The implications for the earth's dynamo are discussed. 相似文献