Global distribution of electron temperature and density fluctuations measured by AEROS-B     

Ch. Münther  K. Spenner  E. Neske 《地球物理与天体物理流体动力学》2013,107(1):141-150

Abstract

Between July 1974 and September 1975 aboard AEROS-B the electron temperature and the electron density have been measured by the Retarding Potential Analyses and the Impedance Probe respectively in the altitude range 200–870 km. Temperature and density fluctuations along satellite paths have been analysed by digital filtering. The large amount of data allows the mean fluctuations at different heights and latitude intervals to be evaluated. The resulting two-dimensional arrays are presented for some time periods. The global distributions show different patterns in the polar and equatorial regions, and seasonal variations. Mean temperature fluctuations and fluctuations of electron density in general occur simultaneously though with different amplitudes. At high latitudes a seasonal dependence in the strength of the fluctuations of both quantities was observed.  相似文献   

A proposed structure–groundwater model: application to chalky media of the Paris Basin     

S. Lallahem  Ch. Lamouroux  J. Mania  A. Hani 《水文研究》2007,21(22):3072-3077

The groundwater flow in a fissured chalky environment at the northern border of the Paris Basin depends on several geological and hydrogeological parameters. Although the studied sector of the basin presents a homogeneous rock type, it is affected by a fracture network. In this type of environment, in which the permeability is low, the groundwater flow displays significant disruption, which is localized in the Fruges region (northern France). The interconnection of the discontinuities (network of fault and/or joints) is reliant on the structural control of groundwater flow through increases in the hydraulic connection between the unsaturated and the saturated zone. The methodology developed herein makes use of microstructural and regional analysis of the fracture patterns, and allowed consideration of the piezometric variations of the chalk aquifer during periods of low and high groundwater levels (April and October 2001) and a diagraphic representation of the estimated physical parameters (electrical resistivity). This enabled us to construct a ‘flow structure’ conceptual model in which we identify two types of faults: tight walls and flow paths that control the piezometric heads and the flow rate. Model validation was carried out on a similar sector. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

Procedure for the selection of runout model parameters from landslide back-analyses: application to the Metropolitan Area of San Salvador, El Salvador   总被引：1，自引：1，他引：0  

José Cepeda  José Alexander Chávez  Celina Cruz Martínez 《Landslides》2010,7(2):105-116

The existing procedures for the selection of runout model parameters from back-analyses do not allow integrating different types of runout criteria and generally lack a systematic approach. A new method based on receiver operating characteristic (ROC) analyses and aimed at overcoming these limitations is herein proposed. The method consists of estimating discrete classifiers for every runout simulation associated with a set of model parameters. The set of parameters that yields the best prediction is selected using ROC metrics and space. The procedure is illustrated with the back-analyses of a rainfall-triggered debris flow that killed 300–500 people in the Metropolitan Area of San Salvador in 1982. The selected model parameters are used to estimate forward predictions for scenarios that correspond to different return periods. The proposed procedure may be useful in the assessment of areas potentially affected by landslides. In turn, this information can be used in the production or updating of land use plans and zonations, similar to that currently being carried out by the Office for Urban Planning of the Metropolitan Area of San Salvador in El Salvador.  相似文献   

Comment on Tectonic relationships of Southwest Iberia with the allochthons of Northwest Iberia and the Moroccan Variscides by J.F. Simancas et al. [C. R. Geoscience 341 (2009) 103–113]     

André Michard  Hassan Ouanaimi  Christian Hoepffner  Abderrahmane Soulaimani  Lahssen Baidder 《Comptes Rendus Geoscience》2010,342(2):170-174

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Geo-Characterization at selected accelerometric stations in Crete (Greece) and comparison of earthquake data recordings with EC8 elastic spectra   总被引：1，自引：0，他引：1  

A. Savvaidis  B. Margaris  N. Theodoulidis  V. Lekidis  Ch. Karakostas  C. Loupasakis  D. Rozos  P. Soupios  M. -D. Mangriotis  U. Dikmen  Par. Tsangaratos  E. Kokinou  A. Vafidis  Th. Rondoyanni  I. Kalogeras  S. Koutrakis  A. Sarris  N. Papadopoulos 《Central European Journal of Geosciences》2014,6(1):88-103

To estimate the seismic response according to Eurocode (EC8) and almost all other national codes, site conditions have to be properly characterized so that soil amplification and the corresponding peak ground motion can be calculated. In this work, different geophysical and geotechnical methods are combined in order to define the detailed ground conditions in selected sites of the Hellenic Accelerometric Network (HAN) in Crete. For this purpose, the geological information of the sites and shear wave velocity, calculated from surface wave measurements, is used. Additionally, ground acceleration data recorded through HAN have been utilized from intermediate depth earthquakes in the broader area of South Aegean Sea. Using the recorded ground motion data and the procedure defined in EC8, the corresponding elastic response spectrum is calculated for the selected sites. The resulting information is compared to the values defined in the corresponding EC8 spectrum for the seismic zone that includes the island of Crete. The comparison shows that accurate definition of ground type through geological, geotechnical and geophysical investigations is important. However, our current comparison focuses on the distribution of values rather than the absolute values of EC8-prescribed spectra, and the results should be considered in this context.  相似文献   

New approach for interpretation of scattered ground magnetic data in a part of Delhi Fold Belt-NW Indian shield     

Prabhakara Prasad P.  Satish Kumar K.  Seshunarayana T.  Rama Rao Ch. 《Arabian Journal of Geosciences》2014,7(7):2633-2639

Randomly distributed ground magnetic data sets, collected along parallel and closely spaced profiles, in small blocks, the blocks being separated/distributed widely over a large area, become, sometimes, unamenable for deriving a meaningful geological model. In such a situation, an approach of “Cumulative Total Intensity Magnetic Anomaly Field (CTIMAF)” has been devised to interpret the sparsely distributed magnetic data sets. A case history has been presented from the lead–zinc mineralized provenance of Ajabgarh Formation of Delhi Fold Belt in the northern part of Ajmer Town. Log-normalized radially averaged power spectrum was computed for the Cumulative Total Intensity Magnetic Anomaly data and depth to the basement is derived. The computed depth of 4.5 km is in good agreement with the Deep Seismic Studies.  相似文献   

Climate change and infectious diseases: Can we meet the needs for better prediction?     

Xavier Rodó  Mercedes Pascual  Francisco J. Doblas-Reyes  Alexander Gershunov  Dáithí A. Stone  Filippo Giorgi  Peter J. Hudson  James Kinter  Miquel-Àngel Rodríguez-Arias  Nils Ch. Stenseth  David Alonso  Javier García-Serrano  Andrew P. Dobson 《Climatic change》2013,118(3-4):625-640

The next generation of climate-driven, disease prediction models will most likely require a mechanistically based, dynamical framework that parameterizes key processes at a variety of locations. Over the next two decades, consensus climate predictions make it possible to produce forecasts for a number of important infectious diseases that are largely independent of the uncertainty of longer-term emissions scenarios. In particular, the role of climate in the modulation of seasonal disease transmission needs to be unravelled from the complex dynamics resulting from the interaction of transmission with herd immunity and intervention measures that depend upon previous burdens of infection. Progress is also needed to solve the mismatch between climate projections and disease projections at the scale of public health interventions. In the time horizon of seasons to years, early warning systems should benefit from current developments on multi-model ensemble climate prediction systems, particularly in areas where high skill levels of climate models coincide with regions where large epidemics take place. A better understanding of the role of climate extremes on infectious diseases is urgently needed.  相似文献   

Edge-on boxy profiles in non-barred disc galaxies     

P. A. Patsis  E. Athanassoula  P. Grosbøl  Ch. Skokos 《Monthly notices of the Royal Astronomical Society》2002,335(4):1049-1053

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Satellite antenna phase center offsets and scale errors in GPS solutions   总被引：5，自引：3，他引：2  

S. Y. Zhu  F.-H. Massmann  Y. Yu  Ch. Reigber 《Journal of Geodesy》2003,76(11-12):668-672

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Radio observations of filaments at metric and decimetric wavelengths     

Ch. Marqué  P. Lantos  J.M. Delouis  C.E Alissandrakis 《Astrophysics and Space Science》2001,277(1-2):329-330

A filament eruption at decimetric wavelength is illustrated here, involving a quiescent filament seen in absorption. A CME occurs in the vicinity of the event. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献