共查询到20条相似文献,搜索用时 62 毫秒
1.
N. M. Firstova V. I. Polyakov V. I. Skomorovsky V. M. Grigoriev 《Geomagnetism and Aeronomy》2009,49(7):927-934
Impact linear polarization in solar flares is studied with the Large Solar Vacuum Telescope (LSVT) using the spectral polarimetric
method. This method makes it possible to minimize the effect of instrumental polarization with an error of up to 10−2 owing to the normalization of the spectral line intensity to the continuum spectrum intensity with negligible linear polarization.
As a result, the Hα line intensity in two orthogonally polarized spectral stripes coincides in the absence of solar polarization.
However, in the presence of linear polarization in a flare, the spectral polarimetric method does not rule out that the error
can be present in determining the Stokes parameters Q and U because of their possible relative “leakage.” Linear instrumental polarization of LSVT has been performed using polaroid
rotation before the major mirror. Twelve elements of a telescope matrix, characterizing linear polarization, have been determined.
The usage of a matrix makes it possible to specify the observed Q and U values accurate to 10−3 of their magnitude. 相似文献
2.
E. L. Afraimovich I. K. Edemsky S. V. Voeykov Yu. V. Yasukevich I. V. Zhivetiev 《Geomagnetism and Aeronomy》2010,50(1):79-95
The morphology of medium-scale traveling wave packets is for the first time presented based on the total electron content
(TEC), measured at the global network of GPS receivers (up to 1500 stations) during the long period (from 1998 to 2007) and
at the GPS/GEONET dense Japan network (1220 stations) in 2008—2009. In the time domain, these packets are chains of narrowband
TEC variations (trains) with a duration of about 1—2 h, a total duration of up to 6 h, and a variation period of 10—30 min.
In the winter Northern Hemisphere, traveling wave packets are observed mostly 3 h after the passage of the morning solar terminator.
In the equinox they appear after the passage of the solar terminator without a pronounced delay or advance. In summer traveling
wave packets are registered 1.5—2 h before the appearance of the evening solar terminator at the observation point when the
solar terminator passes in the magnetically conjugate region. The spatial structure of traveling wave packets is characterized
by a high degree of anisotropy and coherence at a distance larger than ten wavelengths (the wavelength is 100—300 km). A high
quality of the oscillatory system and synchronization with the appearance of the solar terminator at the observation point
and in the magnetically conjugate region indicate that the generation of traveling wave packets by the solar terminator is
of the MHD nature. Our results for the first time experimentally confirm the hypothesis that the solar terminator generates
ion sound waves, proposed by Huba et al. [2000b]. 相似文献
3.
太阳X_EUV成像望远镜用来监测和预报影响空间天气变化的太阳活动,专门服务于空间天气预报研究. 望远镜工作在4~100?的X射线波段和195?极紫外谱段,视场角45′,角度分辨5″,提供全日面、高分辨的成像观测. 文中分析了太阳X、EUV波段的成像观测应用,介绍了X_EUV望远镜的基本设计,分析了望远镜对不同温度日冕等离子体的敏感性、对不同太阳活动现象的响应及反演日冕等离子体参数过滤片的组合利用. 太阳X_EUV成像望远镜集成了掠入射望远镜和正入射望远镜两套系统,扩展了单一X射线望远镜的成像功能,能够观测更多的太阳爆发先兆现象或者伴生现象,是目前国际上同类仪器中最新的太阳成像监测仪器. 相似文献
4.
T. I. Kaltman V. M. Bogod A. G. Stupishin L. V. Yasnov 《Geomagnetism and Aeronomy》2013,53(8):1030-1034
The physical conditions in the low corona and chromosphere of solar active regions are studied. A diagnostics technique based on multiwave observations in the centimeter range, photospheric magnetic field extrapolation, and radioemission calculations has been applied. The calculated spatial and spectral structure of the radioemission has been compared with RATAN-600 spectral-polarization observations with a high spatial resolution. The effect of the plasma physical parameters on the emission structure character in a complex magnetic field topology in active regions is analyzed. Modeling of the spectral singularities at a quasi-periodic propagation of the radioemission is presented. 相似文献
5.
A. V. Belov E. A. Eroshenko O. N. Kryakunova V. G. Kurt V. G. Yanke 《Geomagnetism and Aeronomy》2010,50(1):21-33
The catalog of ground level enhancements of solar cosmic rays during cycles 21—23 of solar activity has been presented. The
main properties, time distribution, and relation of these events to solar sources and proton enhancements observed on satellites
have been studied. 相似文献
6.
Solar faculae are among the most common manifestations of solar activity and can play an important role in the energy transfer from the lower solar atmosphere into the corona. However, the mechanisms by which energy is transferred remain insufficiently studied. Our work is based on observational data obtained with the AST telescope of the Sayan solar observatory. Simultaneous observations were performed in the Hα 6563 Å and FeI 6569 Å, BaII 4554 Å and FeI 4551.6 Å, and CaII 8542 Å and FeI 8538 Å pairs of spectral lines. The studies indicated that the spectral composition of the line-of-sight (LOS) velocity oscillations in faculae is inhomogeneous and is affected by the chromospheric network’s structural elements. The possible presence of short and low magnetic loops in the facula region makes it difficult to determine the unambiguous phase relations between chromospheric and photospheric oscillations. The LOS velocity oscillation signals registered at the chromospheric level both lead and lag behind the signals registered at the photospheric level. At the same time, signs of propagating waves are evidently registered in the chromosphere of individual faculae. 相似文献
7.
This paper addresses observed variations in cosmic ray (CR) intensity, the interplanetary magnetic field (IMF), the solar
wind (SW) turbulence energy spectrum, and the energy spectrum index of Forbush decreases in the 20th–23rd solar cycles. Unlike
the previous three cycles, there are some distinctive features in the 23rd solar cycle. The entire cycle shows a considerable
increase in the index of the SW turbulence energy spectrum inclination and an substantially harder energy spectrum of Forbush
decreases. The anomalously high flux of high-energy CRs and the anomalously low level of the IMF strength were recorded at
the end of this cycle. The conclusion has been made that such unusual CR behavior is associated with a decrease in the degree
of scattering in the resonance interaction between CR fluxes and SW inhomogeneities with spatial scales of ∼1012 cm. 相似文献
8.
《Journal of Atmospheric and Solar》2000,62(16):1553-1559
This is a first report of combined observations form the solar instruments at the recently inaugurated German–Argentinean Solar-Observatory at El Leoncito, San Juan, Argentina. The Hα telescope (HASTA) and the mirror coronagraph (MICA) daily image the solar disk and the inner solar corona respectively with high temporal and spatial resolution. The excellent weather conditions for solar studies of the Observatory, and its south equatorial location allow a complementary summer-condition data with respect to the majority of the other observatories, mainly located in the northern hemisphere. In this paper, we present four events in order to study possible correlations between observations taken by both telescopes. Since each instrument records data in quite different temperature regimes, correlation between both set of data appears when the phenomena span a broad range of temperatures. This is explicitly shown for two of the four set of data presented here. On the other hand, the four cases are good examples of the contributions the two instruments can provide to the better understanding of the mechanisms at work in the inner solar atmosphere. 相似文献
9.
S. V. Lesovoy A. T. Altyntsev V. G. Zandanov E. F. Ivanov A. V. Gubin A. I. Maslov 《Geomagnetism and Aeronomy》2009,49(8):1125-1127
An upgrade of the Siberian Solar Radio Telescope (SSRT) [Smolkov et al., 1986; Grechnev et al., 2003] to a multiwave radio
heliograph has been started. The radio heliograph being created will be designed mainly to measure coronal magnetic fields,
to determine the locations of solar-flare energy release, and to investigate coronal mass ejections. These tasks define the
parameters of next-generation radio heliographs. A high spatial resolution, a high image acquisition rate, and a high sensitivity
are required simultaneously. All these parameters should be realized in the widest possible frequency range—from fractions
to tens of GHz). The expected parameters of the future SSRT-based radio heliograph are listed below: spatial resolution 12″–24″,
temporal resolution 0.02–1.0 s, frequency range 4–8 GHz, sensitivity up to 100 K, left-hand and right-hand circular polarizations,
data rate 0.5–20 Mb s−1 (normal and flare modes). In this paper, we describe the broadband antennas, analog optical data transmission lines, and
correlator used in the 10-antenna radio heliograph prototype. 相似文献
10.
图象重建是一个求逆过程具有不适定性。本文介绍的是一种从少数投影数据进行图象重建的线性代数法-Phillips-Tikhonov正则化方法,同时选择优化工具GCV确定最优的正则参数。为验证该方法,我们对日本Yohkoh卫星上塔载的硬X射线望远镜(HXT)拍摄的太阳图象进行重建。 相似文献
11.
L. F. Chernogor 《Geomagnetism and Aeronomy》2010,50(3):346-361
Quasi-periodic variations in the Doppler shift of the HF range frequency at a vertical path and critical frequency of the
F
2 layer caused by wave disturbances in the ionosphere on the day of the partial (the magnitude was about 0.42) solar eclipse
and on background days are analyzed. For the spectral analysis, the window Fourier transform, adaptive Fourier transform,
and wavelet analysis were jointly used. It is shown that on the day of the eclipse and the background day, spectral characteristics
of wave disturbances within the 150–200 km height range differed substantially. The changes in the spectral composition began
approximately 30–35 min after the solar eclipse beginning and lasted more than 1.5 h. 相似文献
12.
José Maria Santos Luís Reino João Oliveira Paulo Pinheiro Pedro Raposo Almeida Rui Cortes Maria Teresa Ferreira 《Aquatic Sciences - Research Across Boundaries》2011,73(2):233-245
Knowledge of the distribution of species life stages at multiple spatial scales is fundamental to both a proper assessment
of species management and conservation programmes and the ability to predict the consequences of human disturbances for river
systems. The habitat requirements of three native cyprinid species—the Iberian barbel Barbus bocagei Steindachner, the Iberian straight-mouth nase Pseudochondrostoma polylepis (Steindachner), and the Northern straight-mouth nase Pseudochondrostoma duriense (Coelho)—were examined at 174 undisturbed or minimally disturbed sites in 8 river catchments across western Iberia, by modelling
occurrence and counts of species life stages at two spatial scales—large (regional) and instream (local)—using hurdle models.
All the life stages of the barbel showed a negative association with upstream high-gradient river reaches, whereas juvenile
P. duriense favoured such areas. Stream width and openness were negatively related with the occurrence of juvenile and small adult barbel,
but not with large adults. Juvenile nase, on the other hand, were found to be mainly confined to fast-flowing habitats with
high instream cover and coarser substrata. Advanced life stages of the barbel were mainly associated with the “pure” regional
and shared components, whereas the purely local attributes accounted for much of the model variation among nases, in particular
juveniles, and juvenile barbel. The results of this study are useful for setting or refining management goals, and highlight
the need to separately consider life stages when performing conservation-related studies of species distribution. 相似文献
13.
V. I. Skomorovsky V. D. Trifonov G. P. Mashinch Yu. S. Zaiganova V. G. Fainshtein G. I. Kushtal’ S. A. Chuprakov 《Geomagnetism and Aeronomy》2011,51(8):1063-1077
A new telescope has been created to investigate the solar corona during eclipses. One lens simultaneously forms three corona
images occurring as coronal radiation passes through three polarizers with transmission directions rotated 0°, 60°, and 120°
relative to the selected direction; in addition, one image is formed without the polarizer. The telescope was used for solar
corona observation during the eclipse of August 1, 2008. We obtained the distributions of polarization brightness, K corona
brightness, degree of K corona polarization, and total degree of polarization as well as polarization directions depending
on the latitude and radius in the sky plane. Radial distributions of the electron density depending on latitude were calculated.
The coronal plasma temperature was determined for different corona structures under the assumption of hydrostatic equilibrium. 相似文献
14.
The αΩ-dynamo model with casual fluctuations of parameter α reproduces all main indications of solar grand minimums and maximums.
If we take the dependence of turbulent diffusivity on the magnetic field into account, we obtain the phenomenon of hysteresis,
when two solutions are possible in a certain interval of dynamo number values: decaying oscillations of weak fields and magnetic
cycles with a constant and a large amplitude, which are formed depending on initial conditions. Fluctuations in parameter
α result in transitions between these regimes, and the computations indicate that magnetic cycles with a relative large amplitude
alternate with epochs of weak magnetic fields. Such behavior can be used as a model of grand minimums and maximums of solar
activity. 相似文献
15.
The studies are based on the experimental mass sounding of the interplanetary plasma near the Sun at radial distances of R = 4−70 R
S, performed at Pushchino RAO, Russian Academy of Sciences, and on the calculated magnetic fields in the solar corona based
on the magnetic field strength and structure measured on the Sun’s surface at J. Wilcox Solar Observatory, United States.
The experimental data make it possible to localize the position of the boundary closest to the Sun of the transition transonic
region of the solar wind in the near-solar space (R ≈ 10−20 R
S) and to perform an interrelated study of the solar wind structure and its sources, namely, the magnetic field components
in the solar corona based on these data. An analysis of the evolution of the flow types in 2000–2007 makes it possible to
formulate the physically justified criterion responsible for the time boundaries of different epochs in the solar activity
cycle. 相似文献
16.
V. I. Larkina 《Geomagnetism and Aeronomy》2009,49(8):1260-1263
The results of recording the intensity of low-frequency electromagnetic emissions at altitudes of the outer ionosphere based
on satellite data at various levels of solar activity have been investigated. The intensity of low-frequency emissions has
been found to depend on the solar activity, i.e., the spatial noise characteristics vary. Mean values of the noise amplitude
variations at various phases of the solar activity cycle are presented. The low-frequency emissions are shown to serve as
a source of information about the processes in the surface plasma; in particular, the state of the radiation belts is judged
from them. The noise carries information about the variations in the particle fluxes intruding into the Earth’s plasmasphere
under various solar activity conditions and about the magnetospheric plasma variations related to the growth of solar activity.
In other words, the electromagnetic low-frequency noise can be a peculiar kind of indicator of the solar activity and the
state of the magnetosphere. 相似文献
17.
G. Cristiani G. Martínez C.H. Mandrini C.G. Gimnez de Castro M.G. Rovira P. Kaufmann H. Levato 《Journal of Atmospheric and Solar》2005,67(17-18):1744
We present a detailed study of a 1B/M6.9 impulsive flare combining high time resolution (1 ms) and instantaneous emission source localization observations at submillimeter frequencies (212 GHz), obtained with the solar submillimeter telescope (SST), and Hα data from the Hα solar telescope for argentina (HASTA). The flare, starting at 16:34 UT, occurred in active region (AR) 9715 (NOAA number) on November 28, 2001, and was followed by an Hα surge. We complement our data with magnetograms from the Michelson Doppler Imager (SOHO/MDI). SST observed a short impulsive burst at 212 GHz, presenting a weak bulk emission (of about 90 sfu) composed of a few shorter duration structures. The integrated Hα and the 212 GHz light curves present a remarkable agreement during the impulsive phase of the event. The delay between both curves stays below 12 s (the time resolution of the Hα telescope). The flare as well as the surge are linked to new flux emergence very close to the main AR bipole. Taking into account the AR magnetic field evolution, we infer that magnetic field reconnection, occurring at low coronal levels, could have been at the origin of the flare; while in the case of surge this would happen at the chromospheric level. 相似文献
18.
The event of March 12–19, 2009, when a moderately high-speed solar wind stream flew around the Earth’s magnetosphere and carried
millihertz ultralow-frequency (ULF) waves, has been analyzed. The stream caused a weak magnetic storm (D
st min = −28 nT). Since March 13, fluxes of energetic (up to relativistic) electrons started increasing in the magnetosphere. Comparison
of the spectra of ULF oscillations observed in the solar wind and magnetosphere and on the Earth’s surface indicated that
a stable common spectral peak was present at frequencies of 3–4 mHz. This fact is interpreted as evidence that waves penetrated
directly from the solar wind into the magnetosphere. Possible scenarios describing the participation of oscillations in the
acceleration of medium-energy (E > 0.6 MeV) and high-energy (E > 2.0 MeV) electrons in the radiation belt are discussed. Based on comparing the event with the moderate magnetic storm of
January 21–22, 2005, we concluded that favorable conditions for analyzing the interaction between the solar wind and the magnetosphere
are formed during a deep minimum of solar activity. 相似文献
19.
We describe the world's largest synthesis radio telescope, the Very Large Array (VLA), and how it can be used to complement observations with the Solar and Heliospheric Observatory (SOHO) and the Yohkoh solar spacecraft. The VLA provides images with high spatial and temporal resolution, often across the visible solar disk. The VLA also detects nonthermal radiation that is not observed with SOHO and Yohkoh, and provides estimates for the coronal magnetic field strengths that are not directly measured by these spacecraft. The VLA data can be combined with SOHO CDS, SOHO EIT, or Yohkoh SXT observations to provide new insights to the compact, variable sources, called blinkers and bright points, in the solar transition region or low corona. A new 400 cm VLA system provides images of nonthermal burst activity associated with Coronal Mass Ejections (CMEs), and may detect thermal emission from CMEs, that can be compared with SOHO's LASCO and EIT instruments to obtain new information about the origin and evolution of CMEs. 相似文献
20.
The effect of the 11-year solar cycle on the response of planetary wavenumbers 1 and 2 at 10 and 30 hPa in winter to solar activity oscillations on the time scale of the Sun's rotation (27.2 day) is discussed in terms of statistical spectral analysis. The three oscillations studied are the 27.2 d (period of the Sun's rotation), 25.3 d (periodicity caused by modulation of the 27.2 d stratospheric response by annual atmospheric variation), and 54.4 d (doubled period of the solar rotation). A significant effect of the 11-year solar cycle is found for the 54.4 d periodicity in planetary wavenumber 1, and for the 27.2 and 25.3 d periodicities in planetary wavenumber 2. The effect of the 11-year solar cycle is expressed in the evident differences between the amplitudes of responses of planetary waves at maximum and minimum of the solar cycle: the amplitudes are much larger at high than at low solar activity. The 11-year modulation of planetary wave activity is most pronounced at mid-latitudes, mainly at 40–60°N, where the observed variability of planetary waves is large. The results obtained are in good agreement with results of the recent modeling study by Shindell et al. (Science 284 (1999) 305). 相似文献