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1.
Impact of projected climate change on the hydrology in the headwaters of the Yellow River basin 
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下载免费PDF全文 Yueguan Zhang Fengge Su Zhenchun Hao Chongyu Xu Zhongbo Yu Lu Wang Kai Tong 《水文研究》2015,29(20):4379-4397
Located in the northeast of the Tibetan Plateau, the headwaters of the Yellow River basin (HYRB) are very vulnerable to climate change. In this study, we used the Soil and Water Assessment Tool (SWAT) model to assess the impact of future climate change on this region's hydrological components for the near future period of 2013–2042 under three emission scenarios A1B, A2 and B1. The uncertainty in this evaluation was considered by employing Bayesian model averaging approach on global climate model (GCM) multimodel ensemble projections. First, we evaluated the capability of the SWAT model for streamflow simulation in this basin. Second, the GCMs' monthly ensemble projections were downscaled to daily climate data using the bias‐correction and spatial‐disaggregation method and then were utilized as input into the SWAT model. The results indicate the following: (1) The SWAT model exhibits a good performance for both calibration and validation periods after adjusting parameters in snowmelt module and establishing elevation bands in sub‐basins. (2) The projected precipitation suggests a general increase under all three scenarios, with a larger extent in both A1B and B1 and a slight variation for A2. With regard to temperature, all scenarios show pronounced warming trends, of which A2 displays the largest amplitude. (3) In the terms of total runoff from the whole basin, there is an increasing trend in the future streamflow at Tangnaihai gauge under A1B and B1, while the A2 scenario is characterized by a declining trend. Spatially, A1B and B1 scenarios demonstrate increasing trends across most of the region. Groundwater and surface runoffs indicate similar trends with total runoff, whereas all three scenarios exhibit an increase in actual evapotranspiration. Generally, both A1B and B1 scenarios suggest a warmer and wetter tendency over the HYRB in the forthcoming decades, while the case for A2 indicates a warmer and drier trend. Findings from this study can provide beneficial reference to water resource and eco‐environment management strategies for governmental policymakers. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
2.
Summary A simple model is proposed suitable for studying the effect of the ground layer of the atmosphere, polluted by aerosol, on the albedo. This model is founded on solving the equation of transfer of radiative energy. The numerical results are discussed, particular attention being paid to the analysis of errors due to neglecting the multiple reflection of solar radiation on the aerosol particles. A method which would also include the multiple reflection is proposed, and the conditions under which the presence of the aerosol is responsible for an increase or decrease of the solar radiation balance on the Earth's surface, are analysed. 相似文献
3.
Edward R. Benton 《地球物理与天体物理流体动力学》2013,107(1-4):315-330
Abstract A kinematic approach to short-term geomagnetism has recently been based upon pre-Maxwell frozen-flux electromagnetism. A complete dynamic theory requires coupling fluid dynamics to electromagnetism. A geophysically plausible simplifying assumption for the vertical vorticity balance, namely that the vertical Lorentz torque is negligible, is introduced and its consequences are developed. The simplified coupled magnetohydrodynamic system is shown to conserve a variety of magnetic and vorticity flux integrals. These provide costraints on eligible models for the geomagnetic main field, its secular variation, and the horizontal fluid motions at the top of the core, and so permit a number of tests of the underlying assumptions. 相似文献
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I. E. Nachasova O. V. Pilipenko G. P. Markov 《Izvestiya Physics of the Solid Earth》2016,52(6):889-895
The archaeomagnetic studies of ceramics from the Hermonassa multilayer archaeological monument in the Taman Peninsula provided the data on the intensity of the main geomagnetic field in the past. The data for the interval from VIII to XX centuries A.D. demonstrate a well pronounced decreasing trend in the geomagnetic field intensity during this time. Three stages, each lasting for a few centuries, are distinguished in the variations of the centennial average field which slightly varies within each stage and generally decreases from 70 to ~45 μT during the entire period from VIII to XX centuries A.D. The variations of the geomagnetic field in the interval from XII to XVII centuries A.D. have a form of quasi-harmonic oscillations with a characteristic time of about 300 years. 相似文献
5.
本文分析了河西堡地磁台1980年至1984年期间的传递函数随时间变化与邻区250公里内,4.0级以上地震活动性之间的关系。结果表明,河西堡地磁台在无震时的传递函数A一般为0.18左右,B一般为0.01左右,而在地震之前,A一般呈现出减小变化,变化幅度约为0.05左右,异常持续时间约为7个月至一年。而震前B的变化呈增大变化,变化幅度约为0.1左右。同时本文指出,河西堡地磁台的传递函数A、B因子均有季节变化,A值夏季小于冬季,B值夏季大于冬季。在扣除季节变化后,以上所述地震前的传递函数A、B的异常幅度较未扣除季节变化的地震前的异常更加明显。 相似文献
6.
S.I. Braginsky 《Physics of the Earth and Planetary Interiors》1976,11(3):191-199
A short review of the present state of the nearly axially-symmetrical dynamo model is given. A simplified theory for hydromagnetic dynamos taking into account the forces acting in the Earth's core is considered. The role of weak core-mantle friction is discussed and a form of solution is suggested which is characterized by a large geostrophic velocity in the core and by a boundary layer of a new type. The consequences of such a model (called model Z) for the Earth's dynamo are discussed. 相似文献
7.
给出了ATC-40迭代求解方法A收敛性的一个数学解释。分析了ATC-40迭代求解方法A和改进的能力谱方法在迭代上的差异,并从数学上证明了改进的能力谱方法有收敛的结果。 相似文献
8.
A combination of two alternative hypotheses regarding the causes of river channel formation is described. A two-factor classification of lowland river channels is suggested. Dual typification of different types of meandering is considered: by the limiting factor (limited and free) and by genesis (developed and undeveloped). The possibility to take into account three factors simultaneously is considered. 相似文献
9.
Summary A new method for calibrating the Sharpe gravimeter was derived in order to eliminate the non-linearity of the scale. 相似文献
10.
The results of multidisciplinary environmental field studies aimed to elucidate the forms of influence of the Tsimlyansk Reservoir onto coastal ecosystems are presented. The ecotone analysis of the ecosystem structure of the reservoir coast is proposed as an approach to the analysis of the collected data. A brief characteristic of a version of a geographic information system based on field and remote-sensing data is given. A relationship is shown to exist between the reservoir level regime according to 10-year data and the transformation of vegetation cover on the coast against the background of minor changes in soils for the 50-year period of reservoir existence. 相似文献
11.
The Newmark average acceleration method is non-dissipative and unconditionally stable, but its accuracy in transient analysis of wave propagation problems depends not only on the spatial discretization but also on the temporal discretization. It has been found that the effects of spatial and temporal discretization when considered separately as commonly done, are far from adequate for most transient analysis. A better criterion manipulating the interdependent relationship between mesh size and time-step magnitude is imperative to achieve sufficiently accurate results of analysis. In this paper, the accuracy of the Newmark method is investigated by considering the two basic sources of errors, namely, numerical amplitude dissipation and velocity dispersion. The effects of both spatial and temporal discretizations are considered. A new technique to describe the characteristics of various frequency spectra is established. A criterion for mesh design and the selection of time-step magnitude is also proposed based on the combined effects of the amplitude dissipation and velocity dispersion. The efficiency and effectiveness of the proposed criterion are demonstrated using two one-dimensional wave propagation problems. A two-dimensional application shows that this criterion is equally applicable to multidimensional problems. 相似文献
12.
A contiuous recording instrument with field effect transistors has been developed to study the point discharge currents in the atmosphere. The chief advantages of the present instrument are that it is portable and has a range of measurement from 10–9 A to 10–7 A for positive currents and 10–9 A to 10–5 A for negative currents on a linear scale. 相似文献
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14.
Adushkin V. V. Rybnov Yu. S. Spivak A. A. Kharlamov V. A. 《Izvestiya Physics of the Solid Earth》2019,55(6):897-906
Izvestiya, Physics of the Solid Earth - Abstract—A new phenomenological model describing the propagation of acoustic disturbances in the stratospheric waveguide is proposed based on... 相似文献
15.
A method of adaptation of the ionospheric channel parameters to the current conditions is proposed. The observational data on the temporal behavior of signals of radio stations with known location and set of working frequencies (the so-called reference stations) are used as information describing the current state of the channel. A facility that makes possible to determine by simple means the moments of radio rises and declines on the reference paths has been created. A technique that relates for these instants working frequencies of the stations with maximum usable frequencies of the paths has been developed. By means of an approximate solution of the inverse problem using the method of characteristics for the calculation of radiowave propagation and the monthly average semiempirical model of the ionosphere, the height profile of electron density in a certain spatial region is refined. The efficiency of the proposed method of adaptation of the ionospheric channel parameters using the data of vertical sounding is assessed and the expediency of practical application of such adaptation is shown. 相似文献
16.
Summary The assymetry of the diurnal variation of radio-wave ionospheric absorption, measured by the A3 method on the 2775 kHz Kiel — Panská Ves circuit, is studied. Almost full symmetry of absorption is observed in winter and autumn. It is explained by electron concentration variations. A remarkable diurnal asymmetry of absorption is observed in spring and particularly in summer. The observed diurnal asymmetry of the electron concentration seems to be insufficient to account completely for the great absorption asymmetry observed. 相似文献
17.
Geomagnetism and Aeronomy - A model of the eruption of a magnetic flux rope with ends rigidly fixed in the photosphere is analyzed. Long and short flux ropes exhibit different scenarios of... 相似文献
18.
Sepúlveda N 《Ground water》2003,41(1):66-71
An algorithm was designed to statistically estimate the areal distribution of water-table altitude. The altitude of the water table was bounded below by the minimum water-table surface and above by the land surface. Using lake elevations and stream stages, and interpolating between lakes and streams, the minimum water-table surface was generated. A multiple linear regression among the minimum water-table altitude, the differerence between land-surface and minimum water-table altitudes, and the water-level measurements from surficial aquifier system wells resulted in a consistently high correlation for all groups of physiographic regions in Florida. A simple linear regression between land-surface and water-level measurements resulted in a root-mean-square residual of 4.23 m, with residuals ranging from -8.78 to 41.54 m. A simple linear regression between the minimum water table and the water-level measurements resulted in a root-mean-square residual of 1.45 m, with residuals ranging from -7.39 to 4.10 m. The application of the multiple linear regression presented herein resulted in a root-mean-square residual of 1.05 m, with residuals ranging from -5.24 to 5.63 m. Results from complete and partial F tests rejected the hypothesis of eliminating any of the regressors in the multiple linear regression presented in this study. 相似文献
19.
Fred Ward 《Pure and Applied Geophysics》1965,60(1):126-128
Summary A test was made of the effect of some measurement biases on the determination of the solar horizontal wind field. The effect of such biases is not detectable. 相似文献
20.
Peter Vajda 《Studia Geophysica et Geodaetica》1992,36(1):51-56
Summary Determination of palaeointensity using the method of anhysteretic magnetising is reported. It is based on the study of the synthetic magnetite of three fractions which was thermoremanently magnetised in a known laboratory field. The experimental data of the anhysteretic magnetisation were treated using cubic splines.A method of determining the palaeointensity from the behaviour of the anhysteretic magnetisation curve is described while using a designed methodology of three types of regimes of the anhysteretic magnetising process.A way of investigating the palaeointensity of a natural rock sample by the method of anhysteretic magnetising is suggested.Presented at 2nd conference on New Trends in Geomagnetism, Castle of Bechyn, Czechoslovakia, September 24–29, 1990. 相似文献