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61.
The genetic and synoptic classifications of the Novorossiysk Bora are created using the data of daily observations at the Novorossiysk meteorological station and other available synoptic information. Obtained are the quantitative criteria of these classifications, and on this base worked out are the basic scenarios of the generation and evolution of this dangerous phenomenon on the Black Sea coast of Russia. According to the genetic classification, the Bora was divided into four types: frontal, air-mass, monsoon, and gravity. Quantitative criteria worked out for each type can be used for the more accurate forecast of this destructive phenomenon near Novorossiysk. According to the synoptic classification, four classes were distinguished: Azores, North Atlantic, Siberian, and Arctic.  相似文献   
62.
63.
This review paper for STIB (Stratosphere-Troposphere Interaction and the Biosphere; a proposed core project for IGBP) summarizes several features of a recently discovered 10–12 year oscillation in the atmosphere on the Northern Hemisphere. The oscillation is especially strong in the stratosphere during the warmer half of the year, but it is evident in the stratosphere and troposphere also in winter if the data are grouped according to the phase of the Quasi-Biennial Oscillation of the wind in the equatorial stratosphere. During the 40 years with data available to describe the oscillation it was phase locked with the 11-year solar cycle.Affiliate Scientist, NCAR.The National Center for Atmospheric Research is sponsored by the National Science Foundation.  相似文献   
64.
Aftershocks have the potential to cause collapse of a structure that has been already damaged by the preceding main shock. Seismic safety of a structure should therefore be ascertained through a damage analysis using the anticipated main shock and few larger-aftershock motions. Simulation of aftershock motions needs characterization of the seismic hazard due to aftershocks, and therefore it will be useful to develop a conditional scaling model that can predict the response spectrum of an anticipated aftershock motion consistent with the design spectrum of the main shock motion anticipated at the same station. In this study an attempt is made to develop a conditional scaling model for the pseudo spectral velocity spectrum via linear regression analysis on the aftershock and main shock recordings for the 1999 Chi–Chi earthquake. It is shown that it may be possible to obtain a simpler and approximate version of the conditional model from an unconditional model. Damage-causing potential of a ground motion also depends on its strong motion duration (SMD) and therefore a conditional scaling model is developed for SMD of the aftershock motion in several narrow frequency-bands. The model is developed for the larger-aftershock motions and it is shown that a reasonable replacement of such a model may be obtainable directly from an unconditional model. Finally, a simple weighted averaging scheme is proposed to obtain the composite SMD from the SMDs for different frequency bands by using the pseudo spectral acceleration spectrum of the motion.  相似文献   
65.
One alternative to reduce global greenhouse gas emissions is to store the emissions in underground geologic sequestration repositories. The efficacy of this approach has been favorably evaluated by numerous authors over the last 15 years. This paper discusses an assessment of the overall feasibility of storing emissions in three different repositories in the Florida panhandle located in the Southeastern United States. The feasibility assessment evaluates both saline aquifers and oil reservoirs located in the panhandle region. The overall feasibility is driven by the available geologic sequestration capacity, the transportation cost to deliver emissions to a respective repository, and other engineering and regulatory issues. The geologic sequestration capacity is generally controlled by the so-called storage efficiency, a variable dependent on the site-specific geology, reservoir conditions, and the injected fluid characteristics. For this paper, storage efficiency for saline repositories was assessed in more detail using numerical modeling. Based on the work completed, the 3 repositories studied have at least 4.55 gigatonnes of capacity to sequester CO2.  相似文献   
66.
Ohne ZusammenfassungVortrag, gehalten in der Hauptversammlung der Geologischen Vereinigung in Frankfurt a. M., am 7. I. 1928. Ausführlichere Mitteilungen über dieses Thema werden im Rahmen einer größeren Abhandlung über die südalpine Mitteltrias an anderer Stelle veröffentlicht werden.  相似文献   
67.
Rice is the major staple food of Asia, and an important source of employment and income in rural areas, particularly in low-income countries. Research has contributed significantly in achieving food security by increasing the yield potential of rice in irrigated systems, reducing the crop maturity period and achieving yield stability by developing resistance against major insects and diseases in the modern high-yielding varieties. Poverty is, however, still extensive in fragile rainfed rice ecosystems where rice yield has remained low, as scientists have yet to develop high-yielding varieties resistant to abiotic stresses and problem soils. Rice production needs to be increased by another 70% over the next 30 years to meet growing food needs. This has to be achieved with less land, less water, and less labor to accommodate the demand for these inputs from the expanding nonagricultural sectors. The challenge to the rice research community is to make further shifts in yield potential of rice for the irrigated systems, to close the yield gaps in the rainfed systems through developing resistance of high yielding varieties to abiotic stresses, and greater understanding of the interactions between genotypes and environment, developing durable resistance against pests and diseases to reduce farmers' dependence on harmful agrochemicals, and to increase efficiency in the use of water, labor and fertilizers. As further intensification of rice cultivation is inevitable, scientists must understand the negative environmental side-effects of increasing rice productivity, to develop appropriate mitigation options.  相似文献   
68.
Summary. The contributions from the oceanic and ionospheric dynamos, Lo and LI respectively, to the geomagnetic lunar daily variation, L , at Alibag, a coastal station in the Indian equatorial region, are calculated from the L harmonics derived from a 41–yr long series of observations. The analysis in the calendar months shows a steady and significant ocean dynamo contribution in the vertical component, Z, in all the months except April. Examination, by an analysis of the data year by year, of the association of Lo and LI with varying solar and magnetic activities reveals, surprisingly, a stable correlation between the magnetic activity index A P and the oceanic part in the horizontal and vertical components but not in declination, which probably indicates the influence of induced currents, along the latitudes, on L o.  相似文献   
69.
Two detailed geoids have been computed in the region of North Jutland. The first computation used marine data in the offshore areas. For the second computation the marine data set was replaced by the sparser airborne gravity data resulting from the AGMASCO campaign of September 1996. The results of comparisons of the geoid heights at on-shore geometric control showed that the geoid heights computed from the airborne gravity data matched in precision those computed using the marine data, supporting the view that airborne techniques have enormous potential for mapping those unsurveyed areas between the land-based data and the off-shore marine or altimetrically derived data. Received: 7 July 1997 / Accepted: 22 April 1998  相似文献   
70.
Soil is a vital part of the natural environment and is always responding to changes in environmental factors, along with the influences of anthropogenic factors and land use changes. The long-term change in soil properties will result in change in soil health and fertility, and hence the soil productivity. Hence, the main aim of this paper focuses on the analysis of land use/land cover (LULC) change pattern in spatial and temporal perspective and to present its impact on soil properties in the Merawu catchment over the period of 18?years. Post classification change detection was performed to quantify the decadal changes in historical LULC over the periods of 1991, 2001 and 2009. The pixel to pixel comparison method was used to detect the LULC of the area. The key LULC types were selected for investigation of soil properties. Soil samples were analysed in situ to measure the physicochemical soil properties. The results of this study show remarkable changes in LULC in the period of 18?years. The effect of land cover change on soil properties, soil compaction and soil strength was found to be significant at a level of <0.05.  相似文献   
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