Synchronous Changes in Dark Current Fluctuations in Two Separate Photomultipliers in Relation to Earth Rotation     

M.V. Fedorov  L.V. Belousov  V.L. Voeikov  T.A. Zenchenko  K.I. Zenchenko  E.V. Pozharski  A.A. Konradov  S.E. Shnoll 《Astrophysics and Space Science》2003,283(1):3-10

We recorded the fluctuations of the dark current in two photomultipliers located 2000 km from each other in different time zones (in International Institute of Biophysics (Neuss, Germany) and in Moscow State University(Moscow, Russia)). We studied the fluctuations by distribution of their amplitudes (histograms of data). Comparison of the histograms obtained in both locations revealed the higher probability of the similarity of the histogram shape for the measurements done at the same local time. This observation is in a good agreement with similar correlations we have previously found in different spatially separated processes. These data suggest that some cosmophysical factors affect many fluctuations processes observed on the Earth. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Observations of magnetic anomaly signatures in Mars Express ASPERA-3 ELS data     

Y. Soobiah  A.J. Coates  D.O. Kataria  R.A. Frahm  J.R. Scherrer  R. Lundin  H. Andersson  A. Grigoriev  H. Koskinen  T. Säles  W. Schmidt  J. Luhmann  D. Williams  C.C. Curtis  B.R. Sandel  M. Carter  A. Fedorov  S. McKenna-Lawler  R. Cerulli-Irelli  P. Wurz  N. Krupp  M. Fränz  C. Dierker 《Icarus》2006,182(2):396-405

Mars Express (MEX) Analyser of Space Plasmas and Energetic Atoms (ASPERA-3) data is providing insights into atmospheric loss on Mars via the solar wind interaction. This process is influenced by both the interplanetary magnetic field (IMF) in the solar wind and by the magnetic ‘anomaly’ regions of the martian crust. We analyse observations from the ASPERA-3 Electron Spectrometer near to such crustal anomalies. We find that the electrons near remanent magnetic fields either increase in flux to form intensified signatures or significantly reduce in flux to form plasma voids. We suggest that cusps intervening neighbouring magnetic anomalies may provide a location for enhanced escape of planetary plasma. Initial statistical analysis shows that intensified signatures are mainly a dayside phenomenon whereas voids are a feature of the night hemisphere.  相似文献   

Structure of the martian wake     

A. Fedorov  E. Budnik  C. Mazelle  R. Lundin  M. Holmström  M. Yamauchi  J.-J. Thocaven  R. Frahm  J. Scherrer  D.R. Linder  E. Kallio  T. Säles  W. Schmidt  J. Luhmann  D. Williams  C.C. Curtis  B.R. Sandel  M. Carter  S. Orsini  M. Maggi  P. Bochsler  J. Woch  K. Asamura 《Icarus》2006,182(2):329-336

We present the first results from the ion mass analyzer IMA of the ASPERA-3 instrument on-board of Mars Express. More than 200 orbits for May 2004-September 2004 time interval have been selected for the statistical study of the distribution of the atmospheric origin ions in the planetary wake. This study shows that the martian magnetotail consists of two different ion regimes. Planetary origin ions of the first regime form the layer adjacent to the magnetic pile-up boundary. These ions are accelerated to energy greater than 2000 eV and exhibit a gradual decreasing of energy down to the planetary tail. The second plasma regime is observed in the planetary shadow. The heavy ions (considered as planetary ones) are accelerated to the energy of the solar wind protons. Obviously the acceleration mechanism is different for the different plasma regimes. Study of two plasma regimes in the frame referred to the interplanetary magnetic field (IMF) direction (we used MGS magnetometer data to obtain the IMF clock angle) clearly shows their spatial anisotropy. The monoenergetic plasma in the planetary shadow is observed only in the narrow angular sector around the positive direction of the interplanetary electric field.  相似文献   

First ENA observations at Mars: Subsolar ENA jet     

Y. Futaana  S. Barabash  M. Holmström  E. Kallio  H. Gunell  R. Lundin  M. Yamauchi  J.D. Winningham  J.R. Sharber  A.J. Coates  D.O. Kataria  P. Riihelä  H. Koskinen  J. Luhmann  D. Williams  C.C. Curtis  B.R. Sandel  M. Carter  A. Fedorov  S. Orsini  M. Maggi  P. Bochsler  J. Woch  K. Asamura 《Icarus》2006,182(2):413-423

The Neutral Particle Detector (NPD), an Energetic Neutral Atom (ENA) sensor of the Analyzer of Space Plasmas and Energetic Atoms (ASPERA-3) on board Mars Express, detected intense fluxes of ENAs emitted from the subsolar region of Mars. The typical ENA fluxes are (4-7) × 10⁵ cm⁻² sr⁻¹ s⁻¹ in the energy range 0.3-3 keV. These ENAs are likely to be generated in the subsolar region of the martian exosphere. As the satellite moved away from Mars, the ENA flux decreased while the field of view of the NPD pointed toward the subsolar region. These decreases occurred very quickly with a time scale of a few tens of seconds in two thirds of the orbits. Such a behavior can be explained by the spacecraft crossing a spatially constrained ENA jet, i.e., a highly directional ENA emission from a compact region of the subsolar exosphere. This ENA jet is highly possible to be emitted conically from the subsolar region. Such directional ENAs can result from the anisotropic solar wind flow around the subsolar region, but this can not be explained in the frame of MHD models.  相似文献   

First ENA observations at Mars: Solar-wind ENAs on the nightside     

K. Brinkfeldt  H. Gunell  P. C:son Brandt  R.A. Frahm  E. Kallio  Y. Futaana  R. Lundin  M. Yamauchi  J.R. Sharber  A.J. Coates  D.O. Kataria  T. Säles  W. Schmidt  J. Luhmann  D. Williams  C.C. Curtis  B.R. Sandel  M. Carter  A. Fedorov  S. McKenna-Lawler  R. Cerulli-Irelli  P. Wurz  N. Krupp  M. Fränz  C. Dierker 《Icarus》2006,182(2):439-447

We present measurements with an Energetic Neutral Atom (ENA) imager on board Mars Express when the spacecraft moves into Mars eclipse. Solar wind ions charge exchange with the extended Mars exosphere to produce ENAs that can spread into the eclipse of Mars due to the ions' thermal spread. Our measurements show a lingering signal from the Sun direction for several minutes as the spacecraft moves into the eclipse. However, our ENA imager is also sensitive to UV photons and we compare the measurements to ENA simulations and a simplified model of UV scattering in the exosphere. Simulations and further comparisons with an electron spectrometer sensitive to photoelectrons generated when UV photons interact with the spacecraft suggest that what we are seeing in Mars' eclipse are ENAs from upstream of the bow shock produced in charge exchange with solar wind ions with a non-zero temperature. The measurements are a precursor to a new technique called ENA sounding to measure solar wind and planetary exosphere properties in the future.  相似文献   

SCR Distribution Function in the Radial IMF Approximation     

Yurij I. Fedorov  Milan Stehlik 《Astrophysics and Space Science》2006,301(1-4):33-41

The transport of cosmic rays in the interplanetary medium is considered in terms of the kinetic equation describing the energetic particle scattering by magnetic irregularities and their focusing by the regular interplanetary magnetic field. The analytical expression for solar cosmic ray distribution function in the approximation of radial regular magnetic field is obtained and the evolution of energetic particle angular distribution is analyzed. The obtained results can be used for the analysis of ground-level enhancements of cosmic ray intensity.  相似文献   

Ion escape at Mars: Comparison of a 3-D hybrid simulation with Mars Express IMA/ASPERA-3 measurements     

E. Kallio  A. Fedorov  T. Säles  W. Schmidt  P. Riihelä  R. Lundin  H. Gunell  Y. Futaana  M. Yamauchi  J.-A. Sauvaud  J.D. Winningham  J.R. Sharber  A.J. Coates  D.O. Kataria  J.G. Luhmann  D. Williams  C.C. Curtis  B.R. Sandel  M. Carter  S. Orsini  M. Maggi  P. Bochsler  J. Woch  K. Asamura 《Icarus》2006,182(2):350-359

We have analysed ion escape at Mars by comparing ASPERA-3/Mars Express ion measurements and a 3-D quasi-neutral hybrid model. As Mars Express does not have a magnetometer onboard, the analysed IMA data are from an orbit when the IMF clock angle was possible to determine from the magnetic field measurements of Mars Global Surveyor. We found that fast escaping planetary ions were observed at the place which, according to the 3-D model, is anticipated to contain accelerated heavy ions originating from the martian ionosphere. The direction of the interplanetary magnetic field was found to affect noticeably which regions can be magnetically connected to Mars Express and to the overall 3-D Mars-solar wind interaction.  相似文献   

The effect of solar wind high-speed streams on the galactic cosmic rays intensity     

Yu. L. Kolesnyk  A. I. Klyuyeva  B. A. Shakhov  Yu. I. Fedorov 《Kinematics and Physics of Celestial Bodies》2016,32(6):265-275

The effect of high-speed recurrent solar wind streams from coronal holes on the galactic cosmic rays intensity is investigated. The distribution of galactic cosmic rays for different solar cycles is considered based on the data of the world network of neutron monitors. Within the inhomogeneous model, which includes a homogeneous background and regions of high-speed streams (HSS’s), the transport equation has been solved and the effect of HSS’s on the spatial distribution of galactic cosmic rays is estimated. It is shown that theoretical calculations are agreed with the experimental results obtained for 2000–2014 under different assumptions about the mean free path of cosmic rays in the corresponding period of HSS’s.  相似文献   

Scalloped depressions and small-sized polygons in western Utopia Planitia,Mars: A new formation hypothesis     

A. Séjourné  F. Costard  J. Gargani  R.J. Soare  A. Fedorov  C. Marmo 《Planetary and Space Science》2011,59(5-6):412-422

Flat-floored depressions with scalloped-shapes and spatially associated small-sized polygons (diameter <～100 m) dot the landscape of western Utopia Planitia (centered at 45°N–95°E). The scalloped depressions are thought to be the result of ice-rich regolith undergoing degradation by sublimation or thaw. Current models suggest that the formation and development of the depressions occur in a poleward direction due to the enhanced sublimation of their equator-facing slopes. By contrast, we propose a conceptual model that shows the equatorward growth of depressions due to preferential degradation by sublimation of their pole-facing slopes. Our model is based on a geomorphological study of the depressions and small-sized polygons in western Utopia Planitia (80°–110°E, 35°–50°N), using images from the High Resolution Imaging Science Experiment (HiRISE) and topographical data from the Mars Orbiter Laser Altimeter (MOLA) and a HiRISE stereo Digital Elevation Model (DEM). Here we describe (i) a morphological evolution of small-sized polygons within the depressions, from low-centered to high-centered, that facilitates one's understanding of depression growth and development; and (ii) occurrence of v-shaped alcoves, failure cracks and semicircular hollows that point to a retrogressive degradation of the pole-facing slopes of depressions. We propose that the development of the depressions is due to heightened insolation of their pole-facing slopes, leading to enhanced sublimation of ground-ice. Based upon the inferred asymmetric insolation, we suggest that the equatorward expansion of depressions occurred during recent high-obliquity periods of Mars.  相似文献   

Stoneley waves in the Biot–Johnson and continuum filtration theories     

V.N. Dorovsky  Yu.V. Perepechko  A.I. Fedorov 《Russian Geology and Geophysics》2012,53(5):475-483

The paper concerns with mathematical modeling of two-velocity media with reference to data on Stoneley wave propagation at the fluid-porous solid interface from experiments by K.W. Winkler, H.L. Liu, and D.J. Johnson. Models obtained within the limits of two theories, that of Biot (Biot–Johnson) and continuum filtration, are investigated in comparison. On this basis, it is discussed whether it is reasonable to include pore tortuosity and frequency-dependent permeability and tortuosity when modeling the mechanics of deforming fluid-saturated porous solids.  相似文献