共查询到20条相似文献，搜索用时 15 毫秒
1.
I. N. Myagkova Yu. S. Shugay I. S. Veselovsky O. S. Yakovchouk 《Solar System Research》2013,47(2):127-140
This paper analyzes variations of flux of relativistic and subrelativistic electrons in the outer radiation belt of the Earth caused by the arrival of recurrent high-speed streams of solar wind during three consecutive solar rotations. The period from April to July 2010 is covered. During this time, an increase in fluxes of relativistic electrons was observed after they had reached a minimum in November 2009–January 2010. Two coronal holes of different polarity, geometry, and location relative to the solar equator were the source of high-speed solar wind streams. The relationship between the efficiency of acceleration of electrons of subrelativistic energies and the amplitude, duration of high-speed streams of solar wind and geomagnetic disturbances, as well as the wave activity in the range of 2–7 mHz, characterized by the ULF index, is confirmed. Significant increases of the flux of relativistic electrons in the outer radiation belt of the Earth were observed during the considered period with an hourly average speed of solar wind streams above 550 km/s and a duration of more than seven days. It is found that the spectrum of electrons in the Earth’s outer radiation belt over the considered period of time was softer during the observation of solar wind streams from the positive polarity coronal hole, even given the amplitude of the solar wind velocity higher than 550 km/s. 相似文献
2.
There are two types of high-speed solar wind streams classified in two categories:coronal-hole and solar-flare-generated streams. These two types are classified in two categories considering the bulk speed, proton density, temperature and magnetic field in the interplanetary medium. Their effects on cosmic ray intensity have been studied on a short-term basis during 1980–1986. Daily means of one middle and one low-latitude set of neutron monitor data have been taken for analysis using the Chree method of superposed epochs. The investigation indicates that the solar-flare-generated high-speed solar wind streams are more effective in producing cosmic ray decreases than are the coronal-hole generated streams. 相似文献
3.
Proton heating at stream interaction regions in the solar wind is investigated based on the solar wind data obtained by Suisei spacecraft between 0.68 and 1.01 AU from the Sun. The deflection angle of the solar wind flow in the ecliptic plane is used to identify the interaction region. In the solar wind flows coming from east of the Sun in low-speed streams and coming from west in high-speed streams, the radial gradient of proton temperature is flattened owing to heating in the interaction region. From comparison of the best-fitted power law dependence of proton temperature on the radial distance in the deflected flow with that in the non-deflected flow, it is suggested that heating in the interaction regions starts around 0.6–0.7 AU from the Sun. 相似文献
4.
Sector-structured interplanetary magnetic field associated with the fast plasma streams in 1985–1996
An analysis of 373 well-defined high-speed solar-wind streams observed at 1 AU during the years 1985–1996 is outlined. The distribution of the occurrence of these streams as a function of Bartels rotation days using the dominant polarity of the interplanetary magnetic field (IMF) associated with the referred fast streams shows that a four-sector pattern for the positive IMF polarity and a two-sector pattern for the negative IMF polarity are the dominant features in the investigated period. The high-speed streams seem to occur at preferred Bartels days: positive polarity streams are most frequent near Bartels days 5 and 18, while negative polarity streams are most frequent in days 14 and 23. Moreover, the corotating streams with positive IMF polarity prefer to occur in days 5 and 18 of the Bartels rotation period, whereas flare-generated streams with negative IMF polarity occur in days 14 and 23. The observed distribution of Bartels days is probably related to the distribution of the solar sources of high-speed solar wind streams as the solar wind carries with it the photospheric magnetic polarity of the solar source region. In addition, the distribution of the streams reveals a similar behaviour during the ascending and the declining phase of the last solar cycle (22nd) in contrast to the previous one where it has an opposite appearance. Determined differences in the characteristics of the sector structured IMF associated with the fast streams of the last cycle with the previous one (21st) and some similarities with the alternate solar cycle (20th) seem to be attributed to the 22-year magnetic cycle and to the polarity reversals of the polar magnetic field of the Sun. As the magnetic sectors are due to multiple crossings of the solar equatorial plane by a large-scale, warped heliospheric current sheet, it is suggested that the two-sector pattern arises from a tilted solar magnetic dipole component and the more commonly observed four-sector pattern from a quadrupole component of the solar interplanetary magnetic field. 相似文献
5.
Arne K. Richter 《Astrophysics and Space Science》1975,36(2):383-405
Applying an Alfvén-Wave-Extended-QRH-approximation and the method of characteristics, we solve the equations of motion for outwardly propagating Alfvén waves analytically for three different cases of an azimuthal dependence of the background solar wind, (a) for a pure fast-slow stream configuration, (b) for the situation where the high-speed stream originates from a diverging magnetic field region, and (c) for the case of (b) and an initially decreasing density configuration (‘coronal hole’). The reaction of these waves on the background state as well as mode-mode coupling effects are neglected. These three solar wind models are discussed shortly. For the superimposed Alfvén waves we find, on an average, that there is a strong azimuthal dependence of all relevant wave parameters which, correlated with the azimuthal distributions of the solar wind variables, leads to good agreements with observations. The signature of high-speed streams and these correlations could clearly indicate solar wind streams originating from ‘coronal holes’. Contrary to the purely radial dependent solar wind, where outwardly propagating Alfvén waves are exclusively refracted towards the radial direction, we now find a refraction nearly perpendicular to the direction of the interplanetary magnetic field in the compression region and closely towards the magnetic field direction down the trailing edge and in the low-speed regime. 相似文献
6.
B. A. Lindblad 《Solar physics》1981,74(1):187-196
An analysis of 346 high-speed solar wind streams observed at 1 AU during 1964–75 is presented. The analysis shows that a two-sector structure was the dominant feature of the interplanetary magnetic field associated with the high-speed solar wind plasma. The high-speed streams occurred at preferred Bartels days: Positive polarity streams were most frequent near Bartels day 4, negative polarity streams were most frequent near Bartels day 17. Since the solar wind carries with it the photospheric magnetic polarity of the solar source region, the observed distribution of Bartels days must indicate a fundamental property of the distribution of the solar sources of high-speed plasma streams. The observations are explained in terms of a tilted dipole model of the solar-interplanetary field.Proceedings of the 14th ESLAB Symposium on Physics of Solar Variations, 16–19 September 1980, Scheveningen, The Netherlands. 相似文献
7.
V.A. Kovalenko 《Planetary and Space Science》1988,36(12):1343-1358
An analysis has been made of the origin of long-term variations in flux density of solar wind particles (nv) for different velocity regimes. The study revealed a relationship of these variations to the area of the polar coronal holes (CH). It is shown that within the framework of the model under development, the main longterm variations of nv are a result of the latitude redistribution of the solar wind mass flux in the heliosphere and are due to changes in the large-scale geometry of the solar plasma flow in the corona.
A study has been made of the variations of nv for high speed solar wind streams. It is found that nv in high speed streams which are formed in CH, decreases from minimum to maximum solar activity. The analysis indicates that this decrease is attributable to the magnetic field strength increase in coronal holes.
It has been found that periods of rapid global changes of background magnetic fields on the Sun are accompanied by a reconfiguration of coronal magnetic fields, rapid changes in the length of quiescent filaments, and by an increase in the density of the particle flux of a high speed solar wind. It has been established that these periods precede the formation of CH, corresponding to the increase in solar wind velocity near the Earth and to enhancement of the level of geomagnetic disturbance. 相似文献
8.
B. A. Lindblad 《Astrophysics and Space Science》1990,170(1-2):55-61
A correlative study is made between inferred solar sources of high-speed solar wind streams and extended white-light coronal features. The solar wind data used in the study consists of 110 co-rotating high-speed plasma streams observed from spacecraft at 1 AU in the period February 1971-December 1974; the coronal data consists of 144 equatorward extensions of polar coronal holes and 15 equatorial coronal holes, derived fromK-coronometer maps of the white-light corona during the same period. Of 110 observed solar wind streams 88 could directly be associated with an equatorward extension of a polar-cap coronal hole and 14 could be associated with a low-latitude equatorial coronal hole. In 8 cases no visible coronal feature was identified. Of 144 identified polar-cap extensions 102 were associated with a high-speed stream observed at 1 AU; 19 coronal features were related in time to data gaps in the solar wind measurements, while 38 features did not give rise to solar wind streams observed at Earth orbit. The probability of an association depended on the heliographic co-latitude of a polar hole extension, being 50% for a polar lobe extending down to 45° co-latitude and 100% for a polar coronal hole extending to 80° co-latitude or more.Paper presented at the 11th European Regional Astronomical Meeting of the IAU on New Windows to the Univese, held 3–8 July, 1989, Tenerife, Canary Islands, Spain. 相似文献
9.
An updated catalog is created of 303 well-defined high-speed solar wind streams that occurred in the time period 2009?–?2016. These streams are identified from solar and interplanetary measurements obtained from the OMNIWeb database as well as from the Solar and Heliospheric Observatory (SOHO) database. This time interval covers the deep minimum observed between the last two Solar Cycles 23 and 24, as well as the ascending, the maximum, and part of the descending phases of the current Solar Cycle 24. The main properties of solar-wind high-speed streams, such as their maximum velocity, their duration, and their possible sources are analyzed in detail. We discuss the relative importance of all those parameters of high-speed solar wind streams and especially of their sources in terms of the different phases of the current cycle. We carry out a comparison between the characteristic parameters of high-speed solar wind streams in the present solar cycle with those of previous solar cycles to understand the dependence of their long-term variation on the cycle phase. Moreover, the present study investigates the varied phenomenology related to the magnetic interactions between these streams and the Earth’s magnetosphere. These interactions can initiate geomagnetic disturbances resulting in geomagnetic storms at Earth that may have impact on technology and endanger human activity and health. 相似文献
10.
Observations of coronal holes, solar wind streams, and geomagnetic disturbances during 1973–1976 are compared in a 27-day pictorial format which shows their long-term evolution. The results leave little doubt that coronal holes are related to the high-speed streams and their associated recurrent geomagnetic disturbances. In particular, these observations strongly support the hypothesis that coronal holes are the solar origin of the high-speed streams observed in the solar wind near the ecliptic plane.Visiting Scientist, Kitt Peak National Observatory, Tucson, Arizona.Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation. 相似文献
11.
Interplanetary magnetic field data compiled by King (1977, 1979) are used to obtain a list of high velocity solar wind streams for the period January 1975 through June 1978. The catalogue is a continuation of a previous list which covered 1964–75. The total number of high-speed solar wind streams listed in the catalogues is 455. 相似文献
12.
High-speed plasma streams identified in the solar wind measurements can be separated into two categories: coronal-hole-associated streams and flare-generated streams. Effects of these plasma streams on cosmic-ray intensity are studied for the period of 1991–1996. It is investigated that both of these high-speed solar wind plasma streams (CS and FGS) are found equally effective in producing the cosmic-ray intensity decrease on short-term basis. 相似文献
13.
Interplanetary magnetic field data obtained from near-Earth spacecraft are used to compile a catalogue of high-velocity solar wind streams for the period June 1978 through October 1982 (Bartels rotations 1980–2039). The compilation of high-velocity streams is a continuation of two previous lists which covered the periods 1964–1975 and 1975–1978, respectively. The total number of high-speed solar wind streams listed in the catalogues is 637 of which 520 are corotating streams and 117 are classified as flare-associated streams. 相似文献
14.
A reference catalogue of 373 well-defined high-speed plasma streams identified in the solar wind measurements from 1985 to 1996 is reported. The data base for this study is the interplanetary plasma/magnetic field data compilation made available by the NSSDC/WDC-A for rockets and satellites (NASA/GSFC-Greenbelt). The main characteristics of those streams, such as the beginning time, the duration, the origin of them (corotating or flare-generated), the interplanetary magnetic field polarity (Stanford magnetic field), are given in the catalogue.The long-term variation in the occurrence rate of high-speed streams shows interesting differences between even and odd solar cycles when catalogues for solar cycles 20, 21, and 22 are considered together. Hence, this catalogue, extended now over three solar cycles, should be useful for studies connected with solar-interplanetary or solar-terrestrial phenomena, and to clarify solar activity in time. 相似文献
15.
Coronal holes as sources of solar wind 总被引：3，自引：0，他引：3
J. T. Nolte A. S. Krieger A. F. Timothy R. E. Gold E. C. Roelof G. Vaiana A. J. Lazarus J. D. Sullivan P. S. McIntosh 《Solar physics》1976,46(2):303-322
We investigate the association of high-speed solar wind with coronal holes during the Skylab mission by: (1) direct comparison of solar wind and coronal X-ray data; (2) comparison of near-equatorial coronal hole area with maximum solar wind velocity in the associated streams; and (3) examination of the correlation between solar and interplanetary magnetic polarities. We find that all large near-equatorial coronal holes seen during the Skylab period were associated with high-velocity solar wind streams observed at 1 AU.Harvard College Observatory-Smithsonian Astrophysical Observatory.A substantial portion of this work was done while a visiting scientist at American Science and Engineering. 相似文献
16.
V. A. Kovalenko 《Solar physics》1981,73(2):383-403
The energy balance of open-field regions of the corona and solar wind and the influence of the flow geometry in the corona upon the density and temperature, are analyzed. It is found that the energy flux arriving at the corona is constant for the corona's open regions with different flow geometries. For the waves heating the corona and solar wind, the dependence of the absorption coefficient on the corona's plasma density is found to be within the range of distances r=1.05–1.5R
. It is shown that the wave absorption is more dependent on electron density than the coronal emission. It is this difference that causes lower-density coronal holes to be colder than quiet regions. It is found that the additional energy flux necessary for providing energy balance of the corona and for producing solar wind is a flux of Alfvén waves, which can provide the energy needed for producing quasi-stationary high-speed solar wind streams. Theoretical models of coronal holes and the question of why the high-speed solar wind streams are precisely flowing out of coronal holes, are discussed. 相似文献
17.
Gong-liang Zhang 《Chinese Astronomy and Astrophysics》1996,20(4):482-486
Observed instances are given in this paper to show that sub-Alfvénic flow can be formed in the quiet and recurrent low-speed solar wind streams. This kind of flow appears in regions with abnormal enhancement of Alfvénic speed and is associated with a specific type of magnetic configuration. 相似文献
18.
N. N. Stepanian S. V. Kuzin V. G. Fainshtein G. V. Rudenko V. M. Malashchuk V. A. Perebeinos N. I. Shtertser R. K. Zhigalkin I. A. Zhitnik A. A. Pertsov 《Solar System Research》2008,42(1):83-89
The relationship between two classes of coronal holes and high-speed quasi-stationary streams of solar wind at the Earth’s orbit is investigated. “Open” coronal holes, whose area is invariable or increases with the height over the solar surface, are rated in the first class, and “closed” coronal holes with areas decreasing with the height are referred to as second-class holes. The parameters of the coronal holes are determined from IR and EUV images and spectroheliograms. It is shown that most open coronal holes can be associated with high-speed solar-wind streams, while most closed coronal holes exhibit a much lower correlation with such streams. 相似文献
19.
C. O. Lee J. G. Luhmann I. de Pater G. M. Mason D. Haggerty I. G. Richardson H. V. Cane L. K. Jian C. T. Russell M. I. Desai 《Solar physics》2010,263(1-2):239-261
We investigate the organization of the low energy energetic particles (≤1 MeV) by solar wind structures, in particular corotating interaction regions (CIRs) and shocks driven by interplanetary coronal mass ejections, during the declining-to-minimum phase of Solar Cycle 23 from Carrington rotation 1999 to 2088 (January 2003 to October 2009). Because CIR-associated particles are very prominent during the solar minimum, the unusually long solar minimum period of this current cycle provides an opportunity to examine the overall organization of CIR energetic particles for a much longer period than during any other minimum since the dawn of the Space Age. We find that the particle enhancements associated with CIRs this minimum period recurred for many solar rotations, up to 30 at times, due to several high-speed solar wind streams that persisted. However, very few significant CIR-related energetic particle enhancements were observed towards the end of our study period, reflecting the overall weak high-speed streams that occurred at this time. We also contrast the solar minimum observations with the declining phase when a number of solar energetic particle events occurred, producing a mixed particle population. In addition, we compare the observations from this minimum period with those from the previous solar cycle. One of the main differences we find is the shorter recurrence rate of the high-speed solar wind streams (～10 solar rotations) and the related CIR energetic particle enhancements for the Solar Cycle 22 minimum period. Overall our study provides insight into the coexistence of different populations of energetic particles, as well as an overview of the large-scale organization of the energetic particle populations approaching the beginning of Solar Cycle 24. 相似文献
20.
We study the modulation of galactic cosmic rays (GCR) due to high-speed streams (HSS) identified in the solar wind. We compare the GCR modulation due to i) streams with different speed, ii) streams of different duration, and iii) streams from different solar sources. We apply the method of superposed-epoch analysis to analyze the interplanetary plasma and field parameters during the passage of streams with distinct plasma and field characteristics. We use the plasma/field characteristics to distinguish various features of solar sources and interplanetary structures, and discuss the observed differences in the cosmic-ray response. We study the influence of speed, duration, and solar sources of the streams on the GCR modulation. We discuss the relative importance of different solar-wind parameters in the modulation process. 相似文献