Monitoring the Dynamics of the Ionosphere–Plasmasphere System by Ground-Based ULF Wave Observations     

Massimo Vellante  Matthias Förster  Michael Pezzopane  Norbert Jakowski  Tie Long Zhang  Umberto Villante  Marcello De Lauretis  Bruno Zolesi  Werner Magnes 《Earth, Moon, and Planets》2009,104(1-4):25-27

Cross-spectral analysis of ULF wave measurements recorded at ground magnetometer stations closely spaced in latitude allows accurate determinations of magnetospheric field line resonance (FLR) frequencies. This is a useful tool for remote sensing temporal and spatial variations of the magnetospheric plasma mass density. The spatial configuration of the South European GeoMagnetic Array (SEGMA, 1.56 <  L <  1.89) offers the possibility to perform such studies at low latitudes allowing to monitor the dynamical coupling between the ionosphere and the inner plasmasphere. As an example of this capability we present the results of a cross-correlation analysis between FLR frequencies and solar EUV irradiance (as monitored by the 10.7-cm solar radio flux F10.7) suggesting that changes in the inner plasmasphere density follow the short-term (27-day) variations of the solar irradiance with a time delay of 1–2 days. As an additional example we present the results of a comparative analysis of FLR measurements, ionospheric vertical soundings and vertical TEC measurements during the development of a geomagnetic storm.  相似文献   

Constraints on turbulent pressure in the X-ray haloes of giant elliptical galaxies from resonant scattering     

N. Werner †  I. Zhuravleva  E. Churazov  A. Simionescu  S. W. Allen  W. Forman  C. Jones  J. S. Kaastra 《Monthly notices of the Royal Astronomical Society》2009,398(1):23-32

The dense cores of X-ray emitting gaseous haloes of large elliptical galaxies with temperatures   kT ≲ 0.8  keV  show two prominent Fe  xvii emission features, which provide a sensitive diagnostic tool to measure the effects of resonant scattering. We present here high-resolution spectra of five bright nearby elliptical galaxies, obtained with the reflection grating spectrometers (RGS) on the XMM-Newton satellite. The spectra for the cores of four of the galaxies show the Fe  xvii line at 15.01 Å being suppressed by resonant scattering. The data for NGC 4636 in particular allow the effects of resonant scattering to be studied in detail and to prove that the 15.01 Å line is suppressed only in the dense core and not in the surrounding regions. Using deprojected density and temperature profiles for this galaxy obtained with the Chandra satellite, we model the radial intensity profiles of the strongest resonance lines, accounting for the effects of resonant scattering, for different values of the characteristic turbulent velocity. Comparing the model to the data, we find that the isotropic turbulent velocities on spatial scales smaller than ≈1 kpc are less than 100 km s⁻¹ and the turbulent pressure support in the galaxy core is smaller than 5 per cent of the thermal pressure at the 90 per cent confidence level, and less than 20 per cent at 95 per cent confidence. Neglecting the effects of resonant scattering in spectral fitting of the inner 2 kpc core of NGC 4636 will lead to underestimates of the chemical abundances of Fe and O by ∼10–20 per cent.  相似文献   

On the polarization of solar microwave bursts observed at 17 GHz     

Werner Wassenberg 《Solar physics》1971,20(1):130-135

The polarization distribution of 17 GHz bursts is studied observed within a period of 1 yr after maximum solar activity. The typical variation of polarization with time of impulsive bursts leads to the conclusion of a thermalization of the emission region in the post-burst phase. The fine structure of the polarization curve of complex bursts is shown and two possible interpretations of the observed inversion of the polarization at 17 GHz during a complex event are given.  相似文献   

Marine Ingressive Events Recorded in Epicontinental Sequences:Example from the Cretaceous Songliao Basin of NE China in Comparison with the Triassic Central Europe Basin of SW Germany     

WANG Pujun  LIU Wanzhu  YIN Xiuzhen  SCHNEIDER Werner  MATTERN Frank 《世界地质(英文版)》2002,5(1)

Songliao Basin is filled predominantly with continental facies sediments including alluvial fan, fluvial plain, fan delta, lacustrine delta, shore - shallow lacustrine, beach salty flat, semi - deep to deep lacustrine, subaqueous gravity flow,lacustrine swamp and pyroclastic sediments. However, some event units were formed during lake - marine linking periods of the Mid - Cretaceous in the basin, which include black shales with high values for salinity (Sr/Ba) , alkalinity ( Ca + Mg)/(Si + Al) , reducibility (Ni + Zn)/Ga and sulfide sulfur as well as heavy isotopes. The Breitenholz -section to be represented for facies comparison with the Cretaceous evaporitic series in Northeast China is localized in Southwest Germany. Stratigraphically it belongs to the Crabfeld Formation of Keuper of the Germanic Triassic corresponding to Ladinian - Carnian of the international reference scale, and is generally called Lower Gipskeuper. The Germanic Triassic was deposited in the epicontinental (cratonic) central Europe Basin. It covered the area in between Great Britain, North Sea, Poland and Southern Germany. It is composed of cyclic deposits of multicolored mudstones, gypsum/anhydrite, and dolomite beds. The two cases of marine ingression - influenced sequences share some common features.  相似文献   

Research on the precambrian in the United States     

Robin Brett 《Precambrian Research》1982,19(2):P1-P2

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Tertiary and Quaternary tectonic faulting in southernmost Illinois     

W. John Nelson  F. Brett Denny  Joseph A. Devera  Leon R. Follmer  John M. Masters 《Engineering Geology》1997,46(3-4):235-258

Tertiary and/or Quaternary tectonic faulting is documented in three areas of southernmost Illinois: the Fluorspar Area Fault Complex (FAFC) in Pope and Massac Counties, the Ste. Genevieve Fault Zone (SGFZ) in Alexander and Union Counties, and the Commerce Fault Zone (CFZ) in Alexander County.

In the FAFC, faults that strike NE and NNE displace Mounds Gravel (late Miocene to early Pleistocene) and, locally, the Metropolis terrace gravel (Pleistocene; pre-Woodfordian). No Woodfordian or younger deposits are deformed. Faults typically outline narrow, linear grabens that formed under tension with a component of strike slip.

North-south to NW-trending vertical faults near the southeast end of the SGFZ displace Eocene sediments. Again, faults outline narrow grabens and show indications of strike slip. Deformed Quaternary sediments have not been observed.

The CFZ, which trends northeast, displaces Mounds Gravel in Illinois and units as young as Peoria Silt (Woodfordian) in Missouri. Quaternary movement has been interpreted as right-lateral strike-slip. The CFZ coincides with a subtle gravity and magnetic lineament and seems to reflect a major feature in the basement. Surface expression in Illinois is subtle, but mafic and ultramafic intrusions, hydrothermal alteration and small faults align with the Commerce geophysical lineament. Earthquake foci in Missouri and Illinois lie on or close to the CFZ; some focal mechanisms fit the fault trend.

Among these structures, only the CFZ exhibits slip that conforms to the current stress field (principal compressive stress axis E-W to ENE-WSW). Possibly, the stress field changed during Neogene time. Alternatively, high fluid pressures or local stress concentrations may have induced slip on less favorably oriented fractures. Tighter constraints are needed on timing, magnitude, and direction of Neogene displacement.  相似文献   

A comparison of methods for detection of phosphate limitation in microalgae   总被引：6，自引：0，他引：6  

John Beardall  Tom Berman  Phil Heraud  Medina Omo Kadiri  Brett R. Light  Graeme Patterson  Simon Roberts  Barbara Sulzberger  Emel Sahan  Urs Uehlinger  Bayden Wood 《Aquatic Sciences - Research Across Boundaries》2001,63(1):107-121

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Thermodynamic data of lawsonite and zoisite in the system CaO–Al2O3–SiO2–H2O based on experimental phase equilibria and calorimetric work     

Klaus-Dieter Grevel  Mirko Schoenitz  Volker Skrok  Alexandra Navrotsky  Werner Schreyer 《Contributions to Mineralogy and Petrology》2002,144(2):255-255

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Estimation of mean water residence times and runoff generation by0 measurements in a Pre-Alpine catchment (Rietholzbach, Eastern Switzerland)     

Tomas Vitvar  Werner Balderer 《Applied Geochemistry》1997,12(6):787-796

Stable isotopes (¹⁸0) are used to investigate hydrological processes in the small Pre-Alpine research catchment Rietholzbach in NE Switzerland. The catchment covers an area of 3.18 km² and ranges from 680 to 960 m a.s.l. The¹⁸0 concentration in rainfall and in runoff at various sites, including a lysimeter installed within the catchment, over a 2-a period are investigated. First, conceptual flow models are applied to determine the mean water residence times of different systems of the basin and their storage properties. As a second approach, the separation of runoff components using¹⁸O and Mg ions as tracer during some storm flow events was carried out. The following flow mechanisms can be identified from the modelling results: (i) lateral hillslope fluxes, which are faster in the part of the Tertiary Molasse sediments and slower in the part of the Quaternary deposits, and (ii) relatively slow vertical infiltration processes through the soil layer within the lysimeter. Mean residence times of 12.5 months result for the total catchment baseflow component and 24.5 months for the baseflow from the upper part of the catchment, respectively. For the lysimeter seepage water, a mean residence time of about 200 days was obtained. During the intensive storm events, a fast reaction of the stored subsurface water due to heavy precipitation and an expulsion of this storage water amounting to a considerable portion of the total basin runoff can be detected.  相似文献   

The solar abundance of tungsten     

Hartmut Holweger  Klaus Werner 《Solar physics》1982,81(1):3-8

Recent measurements of Wi oscillator strengths (Obbarius and Kock, 1982) lead to a solar photospheric abundance of tungsten, log _W = 1.06 ± 0.15 on the scale log _H = 12. The solar W/Si abundance ratio, 0.32 W atoms/10⁶ Si, coincides with that found in carbonaceous chrondrites. Implications for solar-system r-processes abundances are pointed out.  相似文献