Probing Twisted Magnetic Field Using Microwave Observations in an M Class Solar Flare on 11 February, 2014     

I. N. Sharykin  A. A. Kuznetsov  I. I. Myshyakov 《Solar physics》2018,293(2):34

This work demonstrates the possibility of magnetic-field topology investigations using microwave polarimetric observations. We study a solar flare of GOES M1.7 class that occurred on 11 February, 2014. This flare revealed a clear signature of spatial inversion of the radio-emission polarization sign. We show that the observed polarization pattern can be explained by nonthermal gyrosynchrotron emission from the twisted magnetic structure. Using observations of the Reuven Ramaty High Energy Solar Spectroscopic Imager, Nobeyama Radio Observatory, Radio Solar Telescope Network, and Solar Dynamics Observatory, we have determined the parameters of nonthermal electrons and thermal plasma and identified the magnetic structure where the flare energy release occurred. To reconstruct the coronal magnetic field, we use nonlinear force-free field (NLFFF) and potential magnetic-field approaches. Radio emission of nonthermal electrons is simulated by the GX Simulator code using the extrapolated magnetic field and the parameters of nonthermal electrons and thermal plasma inferred from the observations; the model radio maps and spectra are compared with observations. We have found that the potential-magnetic-field approach fails to explain the observed circular polarization pattern; on the other hand, the Stokes-\(V\) map is successfully explained by assuming nonthermal electrons to be distributed along the twisted magnetic structure determined by the NLFFF extrapolation approach. Thus, we show that the radio-polarization maps can be used for diagnosing the topology of the flare magnetic structures where nonthermal electrons are injected.  相似文献   

Powerful Solar Flares in September 2017. Comparison with the Largest Flares in Cycle 24     

E. A. Bruevich  V. V. Bruevich 《Astrophysics》2018,61(2):241-253

  相似文献   

Study on the performance of the micropile-mechanically stabilized earth wall     

Zhi-chao Zhang  Ronald Y. S. Pak  Yu-min Chen  Han-long Liu 《山地科学学报》2018,15(4):825-844

The Micropile-Mechanically Stabilized Earth (MSE) wall, specially designed for mountain roads, is proposed to improve the MSE wall local stability, global stability and impact resistance of roadside barriers. Model tests and the corresponding numerical modeling were conducted to validate the serviceability of the Micropile-MSE wall and the reliability of the numerical method. Then, a parametric study of the stress and deformation of Micropile-MSE wall based on the backfill strength and interfacial friction angle between backfill and backslope is conducted to evaluate its performance. The test results indicate that the surcharge-induced horizontal earth pressure, base pressure and lateral displacement of the wall panel of Micropile-MSE wall decrease. The corresponding numerical results are nearly equal to the measured values. The basic failure mode of MSE wall in steep terrain is the sliding of backfill along the backslope, while A-frame style micropiles are capable of preventing the sliding trend. The maximum resultant displacement can be decreased by 6.25% to 46.9% based on different interfacial friction angles, and the displacement can be reduced by 6% ~ 56.1% based on different backfill strengths. Furthermore, the reduction increases when the interfacial friction angle and internal friction angle of backfill decrease. In addition, the lateral displacement of wall panel, the deformation of backfill decrease and the tension strain of geogrid obviously, which guarantees the MSE wall functions and provides good conditions for mountain roads.  相似文献   

Implementation of the Concept for Creating a Spacecraft Double-Launch System as a Part of the Upper Stages of the Fregat Family     

Ishin  S. V.  Vikulenkov  V. P.  Fedoskin  D. I.  Poreshnev  A. Yu.  Jumahanov  N. B.  Yakovlev  B. D. 《Solar System Research》2020,54(7):690-698

Solar System Research - Abstract—Results of the implementation of a single concept for the development of the double launch system (SDZ) are presented, in particular the SDZ-La5 for the...  相似文献   

Ground-Based and Satellite Observations of the SAR Arc in the MLT Evening Sector at the Beginning of the Magnetic Storm on March 17, 2015     

Ievenko  I. B.  Parnikov  S. G. 《Geomagnetism and Aeronomy》2020,60(6):737-746

Geomagnetism and Aeronomy - Stable auroral red (SAR) arcs are the result of the interaction of energetic ring current ions with the outer plasmasphere (plasmapause). The article analyzes the...  相似文献   

Effects of a Short-Term Increase in the Intensity of 630.0-nm Emissions of Atomic Oxygen [OI] at Lower Thermospheric Altitudes due to Anthropogenic Activity     

Mikhalev  A. V.  Vasilyev  R. V.  Beletskii  A. B. 《Geomagnetism and Aeronomy》2020,60(1):112-120

Geomagnetism and Aeronomy - The paper examines the results of optical observations obtained during Radar Progress experiments to study the effects (the occurrence of extensive, faintly luminous...  相似文献   

Vertical Distribution of Methane in Baikal Water     

Mizandrontsev  I. B.  Kozlov  V. V.  Ivanov  V. G.  Kucher  K. M.  Korneva  E. S.  Granin  N. G. 《Water Resources》2020,47(1):122-129

Water Resources - Data on the vertical distribution of dissolved methane in Baikal water column are analyzed. The zone of open lake now shows an increase in the concentrations of dissolved methane...  相似文献   

Hillslopes in humid-tropical climates aren't always wet: Implications for hydrologic response and landslide initiation in Puerto Rico     

Matthew A. Thomas  Benjamin B. Mirus  Joel B. Smith 《水文研究》2020,34(22):4307-4318

The devastating impacts of the widespread flooding and landsliding in Puerto Rico following the September 2017 landfall of Hurricane Maria highlight the increasingly extreme atmospheric disturbances and enhanced hazard potential in mountainous humid-tropical climate zones. Long-standing conceptual models for hydrologically driven hazards in Puerto Rico posit that hillslope soils remain wet throughout the year, and therefore, that antecedent soil wetness imposes a negligible effect on hazard potential. Our post-Maria in situ hillslope hydrologic observations, however, indicate that while some slopes remain wet throughout the year, others exhibit appreciable seasonal and intra-storm subsurface drainage. Therefore, we evaluated the performance of hydro-meteorological (soil wetness and rainfall) versus intensity-duration (rainfall only) hillslope hydrologic response thresholds that identify the onset of positive pore-water pressure, a predisposing factor for widespread slope instability in this region. Our analyses also consider the role of soil-water storage and infiltration rates on runoff generation, which are relevant factors for flooding hazards. We found that the hydro-meteorological thresholds outperformed intensity-duration thresholds for a seasonally wet, coarse-grained soil, although they did not outperform intensity-duration thresholds for a perennially wet, fine-grained soil. These end-member soils types may also produce radically different stormflow responses, with subsurface flow being more common for the coarse-grained soils underlain by intrusive rocks versus infiltration excess and/or saturation excess for the fine-grained soils underlain by volcaniclastic rocks. We conclude that variability in soil-hydraulic properties, as opposed to climate zone, is the dominant factor that controls runoff generation mechanisms and modulates the relative importance of antecedent soil wetness for our hillslope hydrologic response thresholds.  相似文献   

Climate Oscillations in Southern Bulgaria and Solar Activity: Analysis of Annual Rings of Needle Samples     

Komitov  B.  Kaftan  V. 《Geomagnetism and Aeronomy》2020,60(8):1180-1186

Geomagnetism and Aeronomy - Abstract—The main subject of the study is an analysis of time series of the width of annual rings of spruce and pine (D) that were obtained during the...  相似文献   

Manifestation of Solar-Activity Cycles in the Rhythms of the Lacustrine Banded Clay of the Late Pleistocene and the Modern Era     

Dmitriev  P. B.  Dergachev  V. A.  Tyasto  M. I. 《Geomagnetism and Aeronomy》2020,60(8):1146-1151

Geomagnetism and Aeronomy - The paper considers the ratio between the spectral and time structures of solar activity, which consists of five main cycles (Schwabe, Hale, Brueckner, Gleissberg, and...  相似文献