共查询到20条相似文献,搜索用时 31 毫秒
1.
Stepanov A. E. Khalipov V. L. Kobyakova S. E. Kotova G. A. 《Geomagnetism and Aeronomy》2019,59(5):539-542
Geomagnetism and Aeronomy - Doppler measurement data from the Yakutsk subauroral ionospheric station have been used to reveal for the first time new and previously unknown dynamic phenomena during... 相似文献
2.
Michael J. Rycroft 《Surveys in Geophysics》2007,28(5-6):407-408
3.
Izvestiya, Physics of the Solid Earth - Abstract—Satellite constellations consisting of two spacecraft (SC) pairs moving in different orbits—the so-called next-generation gravity... 相似文献
4.
by Ralf Köber Götz Hornbruch Carsten Leven Lars Tischer Jochen Großmann Peter Dietrich Holger Weiß Andreas Dahmke 《Ground water》2009,47(4):536-546
Most established methods to characterize aquifer structure and hydraulic conductivities of hydrostratigraphical units are not capable of delivering sufficient information in the spatial resolution that is desired for sophisticated numerical contaminant transport modeling and adapted remediation design. With hydraulic investigation methods based on the direct-push (DP) technology such as DP slug tests, DP injection logging, and the hydraulic profiling tool, it is possible to rapidly delineate hydrogeological structures and estimate their hydraulic conductivity in shallow unconsolidated aquifers without the need for wells. A combined application of these tools was used for the investigation of a contaminated German refinery site and for the setup of hydraulic aquifer models. The quality of DP investigation and the models was evaluated by comparisons of tracer transport simulations using these models and measured breakthroughs of two natural gradient tracer tests. Model scenarios considering the information of all tools together showed good reproduction of the measured breakthroughs, indicating the suitability of the approach and a minor impact of potential technical limitations. Using the DP slug tests alone yielded significantly higher deviations for the determined hydraulic conductivities compared to considering two or three of the tools. Realistic aquifer models developed on basis of such combined DP investigation approaches can help optimize remediation concepts or identify flow regimes for aquifers with a complex structure. 相似文献
5.
Abstract. A simple-to-use computer program (FLOWNS) has been developed for generating flow nets for any saturated rectangular domain with any combination of constant head or constant flux (including zero) boundary conditions. The program approximates with discrete values the continuous distributions of potential and stream function using finite-difference approximations of Laplace's equation. The hydraulic conductivity distribution may be anisotropic and/or heterogeneous. A contouring program is required to generate the final stream and equipotential lines. 相似文献
6.
近年来国内外对震前电离层异常扰动进行了大量研究,新的观测证据显示,地震活动前的电离层扰动确实存在,而且在震级大于5级的地震发生前几天到几个小时内的孕震区上空会发生显著电离层扰动。大量工作多是基于地基的空间探测,如,通过雷达测高仪探测的电离层F2层的临界频率扰动和偶发ES层变化,以及通过GPS地面接收器探测的电子浓度总含量扰动等。 相似文献
7.
Space Plasma Exploration by Active Radar (SPEAR): an overview of a future radar facility 总被引:1,自引:0,他引:1
D. M. Wright J. A. Davies T. R. Robinson P. J. Chapman T. K. Yeoman E. C. Thomas M. Lester S. W. H. Cowley A. J. Stocker R. B. Horne F. Honary 《Annales Geophysicae》2000,18(9):1248-1255
SPEAR is a new polar cap HF radar facility which is to be deployed on Svalbard. The principal capabilities of SPEAR will include the generation of artificial plasma irregularities, operation as an all-sky HF radar, the excitation of ULF waves, and remote sounding of the magnetosphere. Operation of SPEAR in conjunction with the multitude of other instruments on Svalbard, including the EISCAT Svalbard radar, and the overlap of its extensive field-of-view with that of several of the HF radars in the SuperDARN network, will enable in-depth diagnosis of many geophysical and plasma phenomena associated with the cusp region and the substorm expansion phase. Moreover, its ability to produce artificial radar aurora will provide a means for the other instruments to undertake polar cap plasma physics experiments in a controlled manner. Another potential use of the facility is in field-line tagging experiments, for coordinated ground-satellite experiments. Here the scientific objectives of SPEAR are detailed, along with the proposed technical specifications of the system. 相似文献
8.
Variation of Permeability with Porosity in Sandstone Diagenesis Interpreted with a Fractal Pore Space Model 总被引:5,自引:0,他引:5
《Pure and Applied Geophysics》2000,157(4):603-619
9.
The validation and subsequent application of the current three-dimensional numerical hydrodynamic model of Chesapeake Bay is presented. The numerical model solves conservation equations for water mass, momentum, salinity, and heat on a boundary-fitted grid in the horizontal plane and a Cartesian z-grid in the vertical. A generalized ADI finite difference scheme is employed in conjunction with mode splitting technique, solving external and the internal modes. The 10-year boundary conditions including tide, slinity, temperature, wind, heat exchange coefficient, river and non-point source flows were constructed. Model validation was accomplished by demonstrating the model's ability to reproduce observed data over time scales ranging from tidal to seasonal periods. The major parameters compared include tidal elevation, intra-tidal and residual velocities, salinity, temperature, stratification, and flux calculated through the Bay mouth.After validation, the model was applied to simulate bay hydrodynamics for the 10 years of 1985–94. These results were used to drive the three-dimensional water quality model of Chesapeake Bay, which is discussed in a companion paper. 相似文献
10.
11.
Liu Dongmin Wang Daqing Du Guoming Yuan Shuai Yu Chang Zhao Meng Fang Li Fu Yuchen Zhang Weiqian Liu Huimin 《Water Resources》2022,49(4):733-742
Water Resources - Following sponge city concept, taking Qunli New District as study object, and planning water-saving green space system (WGSS) that can use rainwater resources. GIS and ArcHydro... 相似文献
12.
在基于GPS数据提取电离层总电子含量(TEC)的过程中,电离层薄壳高度的选择对解算电离层垂直TEC的精度有很大的影响.但由于不可能获得一个真实的从电离层D层到GPS卫星高度的电子密度剖面,关于电离层薄壳高度的选择一直是基于GPS数据解算电离层TEC方法中关注的一个问题.本文利用等离子体GCPM模型,对太阳活动高年(2002)和太阳活动低年(2008)情况下电离层有效薄壳高度的选择进行了仿真计算.结果表明,最佳的薄壳高度在2002年为560 km,而在2008年为695 km.通过对全球八个具有代表性地点的仿真计算,揭示了有效薄壳高度更复杂的变化特点.在白天,最佳薄壳的高度变化不大(500 km至750 km);但在夜晚,最佳薄壳高度变化范围很大,甚至可以超过2000 km.此外,本文还对不同卫星仰角的情况下斜向TEC转换为垂直TEC的误差进行了分析,结果表明:随着卫星仰角的增加,薄壳模型带来的转换误差基本上是单调减少的.因而,在实际应用中,尽可能地采用大仰角的卫星数据有助于提高解算的电离层垂直TEC的精度.最后,对全球不同地点的电离层TEC的仿真研究表明,在电子密度水平梯度较大的地区,应用电离层薄壳模型时会导致电子密度较高处的TEC被高估,而电子密度较低处的TEC被低估,在分析基于GPS数据提取的电离层TEC空间变化时要认识到这一点. 相似文献
13.
A. I. Eltantawy 《Pure and Applied Geophysics》1960,46(1):352-359
Summary A time cross-section was constructed for Cairo during the period 10–31 Dec. 57. The outstanding feature of this cross-section is the periodic existence of high wind maxima associated with high cloud formation. A method was suggested for the location of high wind centers from the thermal field only. Moreover, the climatological means of high clouds showed quick changes in the period of the Jet Stream migration. This has been taken as an evidence of the relation between the subtropical Jet Stream and high cloud formation in the region.Presented by Prof.M. G. El-Fandy 相似文献
14.
15.
16.
The dynamics of solitary Rossby waves (SRWs) embedded in a meridionally sheared, zonally varying background flow are examined using a non-divergent barotropic model centered on a midlatitude g -plane. The zonally varying background flow, which is produced by an external potential vorticity (PV) forcing, yields a modified Korteweg-de Vries (K-dV) equation that governs the spatial-temporal evolution of a disturbance field that contains both Rossby wave packets and SRWs. The modified K-dV equation differs from the classical equation in that the zonally varying background flow, which varies on the same scale as the disturbance field, directly affects the disturbance linear translation speed and linear growth characteristics. In the limit of a locally parallel background flow, equations governing the amplitude and propagation characteristics of SRWs are derived analytically. These equations show, for example, that a sufficiently large (small) translation speed and/or a sufficiently weak (strong) background zonal shear favor transmission (reflection) of the SRW through (from) the jet. Conservation equations are derived showing that time changes in the domain averaged amplitude ("mass") or squared amplitude ("momentum") are due to zonal variation in both the linear, long-wave phase speed and linear growth; dispersion and nonlinearity do not affect the "mass" or "momentum". Provided (1) the background PV forcing is sufficiently small, or (2) the background PV forcing is meridionally symmetric and the disturbance is a SRW, the dynamics of the disturbance field is Hamiltonian and mass and energy are thus conserved. Numerical solutions of the K-dV equation show that the zonally varying background flow yields three general classes of behavior: reflection, transmission, or trapping. Within each class there exists SRWs and Rossby wave packets. SRWs that become trapped within the zonally localized jet region may exhibit the following behaviors: (1) an oscillatory decay to a steady state at the jet center, (2) the creation of additional SRWs within the jet region, or (3) a steady-state wherein the solution has a smoothed step-like structure located downstream along the jet axis. 相似文献
17.
18.
19.
Kudryavtsev I. V. Kaltman T. I. Vatagin P. V. Charikov Yu. E. 《Geomagnetism and Aeronomy》2019,59(7):838-842
Geomagnetism and Aeronomy - The results of numerical simulation of the one-dimensional propagation of fast electrons in a plasma with Langmuir turbulence are presented. The resonant interaction of... 相似文献
20.
Geomagnetism and Aeronomy - The spatio-temporal dynamics of the propagation of fast electrons in solar plasma is examined with consideration of their interaction with Langmuir waves, which are... 相似文献