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991.
This paper considers oil-and-gas provinces and the epochs of hydrocarbon generation in Kamchatka. We distinguish the following
epochs of hydrocarbon generation: the Early Mesozoic, the Early Cretaceous, the Late Cretaceous, the Early Paleogene, the
Late Paleogene, the Miocene, and the Pliocene-Quaternary. We emphasize the fact that all gas generation epochs were related
to deep processes, including volcanism and hydrothermal activity. 相似文献
992.
The dynamics of meteorological elements in the Lena R. Basin is predicted for the XXI century under four IPCC global scenarios of SRES family, corresponding to specified scenarios of the economic, technological, political, and demographic development of the civilization. The obtained predictions are used to simulate variants of possible changes in water balance components in the Lena Basin up to the mid-XXI century. The calculation procedure is based on the use of land-surface model SWAP and a climate scenario generator MAGICC/SCENGEN. 相似文献
993.
A. Y. Levintanus 《地理信息系统科学与遥感》2013,50(1):83-84
The author describes the contents and participation of former Soviet republics in the compilation of a global atlas of desertification, published under the auspices of the United Nations. Translated by H. L. Haslett, Leamington Spa, UK, from: Izvestiya Akademii Nauk SSSR, seriya geograficheskaya, 1991, No. 6, p. 130. 相似文献
994.
The aim of this study was to display distribution and relationships of heavy elements in the unconfined, shallow alluvial aquifers of the lower Jia Bharali catchment and adjoining areas in central part of North Brahmaputra Plain (NBP), India using hydrochemical as well as multivariate statistical techniques such as principal component analysis (PCA) and cluster analysis. The original matrix was made up of 10 trace elements (As, Cd, Cu, Co, Cr, Fe, Mn, Pb, Ni and Zn) estimated from 50 shallow alluvial dug wells in both the wet and the dry season for a duration of 3 hydrological years (2008–2011). Except As, Cu and Zn all the other toxic metals in the shallow aquifers were found exceeding the WHO maximum permissible limits for drinking water. PCA extracted five varimax factors as geogenic, agricultural and anthropogenic explaining about 71.2% of the total variance in the wet season and 69.3% total variance in the dry season. Hierarchical cluster analysis classified the dug wells into two groups in the wet season and three groups in the dry season with respect to the heavy elements. The results emphasized the need for routine monitoring and management in order to avoid contamination of groundwater sources in the NBP with respect to the dissolved trace elements. 相似文献
995.
Emil V. Stanev Jörg-Olaf Wolff Hans Burchard Karsten Bolding Götz Flöser 《Ocean Dynamics》2003,53(1):27-51
In this paper we use a combination of numerical modeling and data analysis to gain a better understanding of the major characteristics
of the circulation in the East Frisian Wadden Sea. In particular, we concentrate on the asymmetry of the tidal wave and its
modulation in the coastal area, which results in a complex pattern of responses to the sea-level forcing from the North Sea.
The numerical simulations are based on the 3-D primitive equation General Estuarine Transport Model (GETM) with a horizontal
resolution of 200 m and terrain-following vertical coordinates. The model is forced at its open boundaries with sea-level
data from an operational model for the German Bight (German Hydrographic Office). The validation data for our model simulations
include time series of tidal gauge data and surface currents measured at a pile in the back-barrier basin of the Island Langeoog,
as well as several ADCP transects in the Accumer Ee tidal inlet.
Circulation and turbulence characteristics are investigated for typical situations driven by spring and neap tides, and the
analysis is focused on dominating temporal and spatial patterns. By investigating the response of five back-barrier basins
with rather different morphologies to external forcing, an attempt is made to elucidate the dominating physical balances controlling
the circulation in the individual sub-basins. It is demonstrated that the friction at the seabed tends to slow down the tidal
signal in the shallow water. This leads to the establishment of flood dominance in the shallow sea north of the barrier islands.
South of the islands, where the water volume of the channels at low tide is smaller than the tidal prism, the asymmetry of
the tidal signal is shifted towards ebb dominance, a feature which is particularly pronounced at spring tide.
At the northern open boundary, the tidal wave propagating from west to east generates a sea-level difference of ∼1 m along
the boundary, and thereby triggers vigorous alongshore currents. The frictional control in the model is located in the inlets,
as well as along the northern boundary. The correlation between velocity and turbulent kinetic energy tends to the establishment
of a net southward transport, giving theoretical support to the observed accumulation of sediments on the intertidal flats.
Weak turbulence along the northern shores of the barrier islands and the small magnitude of the residual currents there promote
accumulation of suspended matter in these areas, although wave action will generally counteract this effect.
Received: 29 May 2002 / Accepted: 26 September 2002
Responsible Editor: Jean-Marie Beckers
Acknowledgements We are indebted to S. Dick for providing the data from the operational model of BSH and to B. Flemming for the useful discussions.
The topography data and Fig. 1 have been prepared in cooperation with F. Meyer. Figure 2 has been prepared by G. Brink-Spalink.
We also thank for the comments from an anonymous reviewer which helped to improve our paper. 相似文献
996.
In order to investigate the effect of detention reservoirs on flood, the precipitation-runoff process as well as the reservoir routing was simulated with the HEC-HMS software. The model was run under four different scenarios (without a reservoir and with an empty, half-full, and full reservoir) and with different return periods of from 2 to 100 years in the Jafar Abad River basin, Golestan province, Iran. The statistical analysis of the results was based on one-way analysis of variance. To study the effect of reservoirs, two indices were used: the Flood Attenuation Rate (FAR) and Storage Ratio (SR). The results indicated that the construction of detention reservoirs leads to the decrease in peak discharge and the volume of flood that leaves the reservoir and postpones the incidence of the peak discharge. The influence of the reservoir diminishes with the prolongation of the return period. The maximum level of flood volume reduction for empty, half-full, and full reservoirs was 61.1, 33.2, and 0.8%, respectively, and for the peak discharge was 63.9, 32.8, and 6.6%, respectively. The maximum value of FAR for reservoirs under empty, half-full, and full conditions were 26, 19, and 7%, respectively. Similarly, the maximum SR for the empty and half-full reservoirs was 14 and 5%, respectively, thus showing the efficiency of reservoirs in flood control. Also, the results demonstrate that the efficiency of reservoirs in flood control not only depends on the reservoir volume and the amount of flood, but also on the geometric properties of the reservoir and weir. 相似文献
997.
J. M. Edwards 《Boundary-Layer Meteorology》2009,132(2):349-350
The structure of the radiatively dominated stable boundary layer is analysed using idealized calculations at high vertical
and spectral resolution. The temperature profile of a nocturnal radiative boundary layer, developing after the evening transition,
is found to be well described in terms of radiative cooling to the surface, although radiative exchanges within the atmosphere
become increasingly important with time. The treatment of non-black surfaces is discussed in some detail and it is shown that
the effect of reducing the surface emissivity is to decrease rather than to increase the radiative cooling rate in the surface
layer. It is also argued that an accurate assessment of the impact of non-black surfaces requires careful attention to the
spectral and directional characteristics of the surface emissivity. A polar nocturnal boundary layer, developing above snow-covered
ground, is simulated and found to reach a slowly evolving state characterized by a strong radiative divergence near the surface
that is comparable to observed values. Radiative boundary layers are characterized by large temperature gradients near the
surface.
An erratum to this article can be found at 相似文献
998.
Extreme midlatitude cyclone characteristics, precipitation, wind speed events, their inter-relationships, and the connection
to large-scale atmospheric patterns are investigated in simulations of a prolonged cold period, known as the Maunder Minimum
from 1640 to 1715 and compared with today. An ensemble of six simulations for the Maunder Minimum as well as a control simulation
for perpetual 1990 conditions are carried out with a coupled atmosphere-ocean general circulation model, i.e., the Climate
Community System Model (CCSM). The comparison of the simulations shows that in a climate state colder than today the occurrence
of cyclones, the extreme events of precipitation and wind speed shift southward in all seasons in the North Atlantic and the
North Pacific. The extremes of cyclone intensity increases significantly in winter in almost all regions, which is related
to a stronger meridional temperature gradient and an increase in lower tropospheric baroclinicity. Extremes of cyclone intensity
in subregions of the North Atlantic are related to extremes in precipitation and in wind speed during winter. Moreover, extremes
of cyclone intensity are also connected to distinct large-scale atmospheric patterns for the different subregions, but these
relationships vanish during summer. Analyzing the mean 1,000 hPa geopotential height change of the Maunder Minimum simulations
compared with the control simulation, we find a similar pattern as the correlation pattern with the cyclone intensity index
of the southern Europe cyclones. This illustrates that changes in the atmospheric high-frequency, i.e., the simulated southward
shift of cyclones in the North Atlantic and the related increase of extreme precipitation and wind speed in particular in
the Mediterranean in winter, are associated with large-scale atmospheric circulation changes. 相似文献
999.
We investigate a three-parameter equation of state for stellar matter under nuclear statistical equilibrium conditions in the ranges of temperatures 3×109–1011 K and densities 104–1013 g cm?3 and for various ratios of the total number of neutrons to the total number of protons within the range 1–1.5. These conditions correspond to the initial stages of the gravitational collapse of iron stellar cores that are accompanied by nonequilibrium matter neutronization. We analyze the effect of the excited levels of atomic nuclei on the thermodynamic properties of the matter. We show that this effect is insignificant at low densities, ρ?1010 g cm?3, but it leads to an expansion of the instability region, γ<4/3, at higher densities. The incorporated effects of the Fermi degeneracy of free nucleons prove to be insignificant, because their concentrations are low at low temperatures. In the future, we plan to investigate the effects of Coulomb interactions and neutron-rich nuclei on the thermodynamic properties of the matter. 相似文献
1000.
To the east of Nanchang,the capital of Kiangsi Province,there cropsout a continuous belt of Permian coal series~1 trending approximately in thedirection from N.E.to S.W.Broadly speaking,this coal belt forms a synclinal 相似文献