共查询到20条相似文献，搜索用时 31 毫秒
1.
K. G. Ivanov 《Geomagnetism and Aeronomy》2009,49(5):557-565
The phenomena of superconcentration of the large-scale field photospheric sources in the main zone of active longitudes, blocking of regular differential rotation by these sources, and origination of the four-sector structure of the solar magnetic field during the decline phase of cycle 23 have been considered in more detail and taking into account the polar correction. It has been indicated that superconcentration was formed due to the penetration of photospheric sources into the zone from the western surroundings of this zone and owing to the generation of the large-scale field in the zone itself. The dynamics of a blocking-induced complex MHD disturbance with reflected from the zone and reconnecting photospheric sources of negative and positive polarity, respectively, and the transformation of the bisector structure into the four-sector one have been considered. It has been indicated that the dynamics of this MHD disturbance was responsible for that of associated solar activity: the generation of sunspot groups, appearance of flares, and, finally, origination of a powerful heliospheric storm and the solar-terrestrial extrastorm of July 22–27, 2004. 相似文献
2.
K. G. Ivanov 《Geomagnetism and Aeronomy》2010,50(3):285-297
The dynamics of the large-scale open field and solar activity at the second stage of the MHD process, including the origination
and disappearance of the four-sector structure during the decline phase of cycle 23 (the stage when the blocking field is
displaced from the main zone of active longitudes), has been considered. Extremely fast changes in the scales of one of new
sectors (from an extremely small sector (“singularity”) to a usual sector that originated after the uniform expansion (“explosion”)
of singularity with a “kick” into the zone of active longitudes, westward motion of the MHD disturbance front in the direction
of solar rotation, and formation of an active quasi-rigidly corotating sector boundary responsible for the heliospheric storm
of November 2004) have been detected in the field dynamics. It has been indicated that a very powerful group of sunspots AR
10656 (which disappeared after the explosion) with an area of up to 1540 ppmh (part per million hemisphere), a considerable
deficit of the external energy release, and zero geoeffectiveness in spite of the closeness to the Earth helioprojection existed
within singularity. It has been assumed that the energy escaped from this group with effort owing to the interaction between
coronal ejections and narrow sector walls (singularity), and a considerable part of the energy was released in the outer layers
of the convective zone, as a result of which singularity exploded and this explosion was accompanied by the above effects
in the large-scale field and solar activity. 相似文献
3.
K. G. Ivanov 《Geomagnetism and Aeronomy》2010,50(6):695-710
A more detailed scenario of one stage (August–November 2004) of the quasibiennial MHD process “Origination ... and dissipation
of the four-sector structure of the solar magnetic field” during the decline phase of cycle 23 has been constructed. It has
been indicated that the following working hypothesis on the propagation of an MHD disturbance westward (in the direction of
solar rotation) and eastward (toward the zone of active longitudes) with the displacement of the large-scale open solar magnetic
field (LOSMF) from this zone can be constructed based on LOSMF model representations and data on sunspot formation, flares,
active filaments, and coronal ejections as well as on the estimated contribution of sporadic energy release to the flare luminosity
and kinetic energy of ejections: (1) The “explosion” of the LOSMF singularity and the formation in the explosion zone of an
anemone active region (AR), which produced the satellite sunspot formation that continued west and east of the “anemone,”
represented a powerful and energy-intensive source of MHD processes at this stage. (2) This resulted in the origination of
two “governing” large-scale MHD processes, which regulated various usual manifestations of solar activity: the fast LOSMF
along the neutral line in the solar atmosphere, strongly affecting the zone of active longitudes, and the slow LOSMF in the
outer layers of the convection zone. The fronts of these processes were identified by powerful (about 1031 erg) coronal ejections. (3) The collision of a wave reflected from the zone of active longitudes with the eastern front of
the hydromagnetic impulse of the convection zone resulted in an increase in LOSMF magnetic fluxes, origination of an active
sector boundary in the zone of active longitudes, shear-convergent motions, and generation and destabilization of the flare-productive
AR 10696 responsible for the heliospheric storm of November 3–10, 2004. 相似文献
4.
Intersector disbalance of the large-scale open solar magnetic field fluxes,active and passive boundaries,and solar-terrestrial extrastorms 总被引：1，自引：1，他引：0
The dynamics (from rotation to rotation) of the absolute values of the large-scale open solar magnetic field fluxes in the four-sector field structure has been considered for the first time, using CRs 2032–2035 in July–October 2005 as examples. An important role of the ratio of the fluxes at the eastern and western sector boundaries (Φ E /Φ W ) is confirmed. As in the cases of the two-sector structure, Φ E /Φ W > 1 is typical of active rigidly corotating boundaries with intense sunspot formation, flares, and interplanetary and geomagnetic disturbances. A remarkable property of the considered structure was the presence of a rapidly increasing flux in an initially narrow sector and the flux interaction with a stable rigidly corotating sector in the zone of the main active longitudes, which caused an unexpectedly strong geoeffective long-range action of flares near the corresponding active boundary. 相似文献
5.
K. G. Ivanov 《Geomagnetism and Aeronomy》2010,50(1):1-14
The effectiveness of the series of powerful heliospheric storms, originated during the decline phase of cycle 23 owing to
the superconcentration of the open field photospheric sources in the main zone of active longitudes, has been studied. The
geoeffectiveness of the storm of July 16—27, 2004, was closely related to the origination of the four-sector structure and
depended on the destabilization of two activity centers weakly and strongly geoeffective with ARs 10649 and 10652. The first
center was localized in one of the new sectors; the second center, in the western surroundings of the zone of active longitudes.
The departure of coronal mass ejections from AR 10649 was substantially hindered: they were completely absent after the series
of powerful X-ray flares, and a rare phenomenon of “sunquake” was observed: shock waves did not reach the Earth in spite of
its favorable position. The Earth was strongly shielded by new sector boundaries from coronal ejections from AR 10652 with
a gradual weakening and disappearance of this region, as a result of which the cascade of three near-Earth storms with an
increasing power and Ap, indices of 52, 154, and 186 originated. Rare phenomena in AR 10649 and the cascade of solar—terrestrial heliospheric storms
made the storm of July 16— 27 a unique phenomenon in cycle 23, and a short-term prediction of its geoeffectiveness was impossible. 相似文献
6.
The solar wind velocity and polarity of the B x-component of the interplanetary magnetic field have been analyzed for the first eight months of 2005. The interplanetary magnetic field had a four-sector structure, which persisted during nine Carrington rotations. Three stable clusters of a high-speed solar wind stream and one cluster of a low-speed stream were observed during one solar rotation. These clusters were associated with the interplanetary magnetic field sectors. The predicted solar wind velocity was calculated since July 2005 one month ahead as an average over several preceding Carrington rotations. The polarity of the B x-component of the interplanetary magnetic field was predicted in a similar way based on the concept of the sector structure of the magnetic field and its relation to maxima of the solar wind velocity. The results indicate a satisfactory agreement of the forecast for two rotations ahead in July–August 2005 and pronounced violation of agreement for the next rotation due to a sudden reconfiguration of the solar corona and strong sporadic processes in September 2005. 相似文献
7.
The solar-terrestrial extrastorm of August 22–25, 2005, has been considered in the context of the cyclic dynamics and structure of the large-scale open solar magnetic field and has been rated among the other extrastorms of cycle 23. It has been established that the storm under discussion was one of the last six extrastorms in the cycle that occurred during the specific third interval of the declining phase—the period of quasirigidly corotating four-sector structure. Inside this structure, we have revealed convergent motions of the photospheric sources of open fields, the active sector boundary, and the formation of a narrow longitudinal sector with the activity complex responsible for the set of four extrastorms of January–September 2005. It is shown that all extrastorms were accompanied by significant variations (up to 1021 μs) of the open field flux Φ. The storm of August 22–25 was accompanied by an increase in the magnetic flux Φ in the corresponding sector (with a doublet of solar flares) and a fast expansion of the sector to the dimensions at the beginning of this interval (September 2004). 相似文献
8.
The structure, configuration, dynamics, and solar sources of the near-Earth MHD disturbance of the solar wind on November 20, 2003, is considered. The disturbances of October 24 and November 22 after flares from the same AR 10484 (10501) are compared. The velocity field in the leading part of the sporadic disturbance is for the first time studied in the coordinate system stationary relative to the bow shock. A possible scenario of the physical processes in the course of this solar-terrestrial storm is discussed in comparison with the previously developed scenario for the storm of July 15, 2000. It has been indicated that (1) the near-Earth disturbance was observed at the sector boundary (HCS) and in its vicinities and (2) the disturbance MHD structure included: the complicated bow shock, wide boundary layer with reconnecting fields at a transition from the shock to the magnetic cloud, magnetic cloud with a magnetic cavity including packed substance of an active filament, and return shock layer (supposedly). It has been found out that the shock front configuration and the velocity field are reproduced at an identical position of AR and HCS relative to the Earth on November 20 and 24. It has been indicated that the maximal magnetic induction in the cloud satisfied the condition B m = (8πn 1 m p)1/2(D ? NV1), i.e., depended on the dynamic impact on the cloud during all three storms [Ivanov et al., 1974]. When the disturbance was related to solar sources, the attention has been paid to the parallelism of the axes of symmetry of the active filament, transient coronal hole, coronal mass ejection, zero line of the open coronal field (HCS), and the axis of the near-Earth magnetic cloud: the regularity previously established in the scenario of the storm of July 15, 2000 [Ivanov et al., 2005]. It has been indicated that the extremely large B m value in the cloud of October 20 was caused by a strong suppression of the series of postflare shocks reflected from the heliospheric streamer. 相似文献
9.
The inhomogeneity of the sunspot group longitude distribution has been determined depending on the rotation period used to determine a longitude. The statistical significance of the found active longitudes has been estimated. It has been indicated that a rather high reliability is reached only when the synodic rotation period is close to 27 and 28 days. In this case active longitudes show the long-term variation related to the north-south asymmetry of the sunspot formation. It is assumed that active longitudes are related to the relic magnetic field frozen in a uniformly rotating solar radiative zone. 相似文献
10.
V. G. Eselevich V. M. Bogod I. V. Chashey M. V. Eselevich Yu. I. Yermolaev 《Geomagnetism and Aeronomy》2009,49(1):133-135
The solar sources of the magnetic storms of November 8 and 10, 2004, are analyzed. The preliminary results of such an analysis [Yermolaev et al., 2005] are critically compared with the results of the paper [Tsurutani et al., 2008], where solar flares were put in correspondence with these magnetic storms. The method for determining solar sources that cause powerful magnetospheric storms is analyzed. It has been indicated that an optimal approach consists in considering coronal mass ejections (CMEs) as storm sources and accompanying flares as additional information about the location of CME origination. 相似文献
11.
K. G. Ivanov 《Geomagnetism and Aeronomy》2013,53(3):291-297
The dynamics of the occurrence frequency and intensity of solar-terrestrial storms at the current solar cycle (cycle 24) onset (2007–2011) is considered. The storms were identified based on the moving semidiurnal average planetary index of activity, beginning from Ap* ≥ 30. It has been established that 12, 11, and 2 only moderate storms (Ap* = 30–49), which were randomly distributed during the year, were successively observed in the first three years. After a prolonged period without storms (August 2009–March 2010), a series of storms with mixed or only moderate activity, which were regularly distributed over the seasons (ecliptic longitudes) from April to August, started appearing beginning from the storm of April 1–6, 2010. This period followed the tendency toward the transformation of the slowly rotating four-sector structure (Large-Scale Open Solar Magnetic Field, LOSMF) from the two-sector structure (March 2010). The first storm in the new cycle (April 2010) was very powerful and originated owing to the successive destabilization of the complex of two magnetic filamentary ropes. It is interesting that the origination of a new LOSMF sector was associated with a 27-day interval, during which thermal neutrons appeared at Kamchatka and volcanoes erupted in Iceland, and a strong earthquake occurred in March 2011 in Japan when the Earth was located precisely in this sector. 相似文献
12.
It was discovered that the dates of the earthquakes of the summer 2012, being ordered in accordance with the corresponding Carrington rotations (CR) of the Sun nos. 2123–2127, form four discrete isolated groups, with a 30-day periodicity of the earthquakes in each group. On the Sun, the moments of the earthquakes correspond to four groups of the discrete Carrington longitudes (CL) of the four-sector structure of the large-scale open solar magnetic field (LOSMF). Close to each time of occurrence of the earthquake, the strong coronal mass ejections (CME) of Halo and Particle Halo types were identified. It was unexpectedly discovered that the occurrence times of the earthquakes and the onsets of CMEs are approximately synchronous, either keeping slightly ahead or lagging somewhat behind each other. This means that the earthquakes and CMEs are governed by a common external factor. The hypothesis that this could have been caused by the influence of Jupiter is supported by the discovered phenomenon of the eclipse of Jupiter by the Sun in May–June 2012, when the Sun occurred between Jupiter and the Earth and a significant decline in the magnitudes of the quakes was detected on the Earth. 相似文献
13.
Bashir W. Sharif 《地球物理与天体物理流体动力学》2013,107(6):493-511
In this article we study the linear instability of the two-dimensional strongly stratified model for global MHD in the diffusive solar tachocline. Gilman and Fox [Gilman, P.A. and Fox, P., Joint instability of the latitudinal differential rotation and toroidal magnetic fields below the solar convection zone. Astrophys. J., 1997, 484, 439–454] showed that for ideal MHD, the observed surface differential rotation becomes more unstable than is predicted by Watson's [Watson, M., Shear instability of differential rotation in stars. Geophys. Astrophys. Fluid Dyn., 1981, 16, 285–298] nonmagnetic analysis. They showed that the solar differential rotation is unstable for essentially all reasonable values of the differential rotation in the presence of an antisymmetric toroidal field. They found that for the broad field case B φ～sinθcosθ, θ being the co-latitude, instability occurs only for the azimuthal m?=?1 mode, and concluded that modes which are symmetric (meridional flow in the same direction) about the equator onset at lower field strengths than the antisymmetric modes. We study the effect of viscosity and magnetic diffusivity in the strongly stably stratified case where diffusion is primarily along the level surfaces. We show that antisymmetric modes are now strongly preferred over symmetric modes, and that diffusion can sometimes be destabilising. Even solid body rotation can be destabilised through the action of magnetic field. In addition, we show that when diffusion is present, instability can occur when the longitudinal wavenumber m?=?2. 相似文献
14.
D. V. Erofeev 《Geomagnetism and Aeronomy》2008,48(2):139-144
The relationship between the IMF azimuthal angle and plasma velocity has been studied independently for three types of solar wind streams (recurrent and transient high-speed streams and low-speed background wind) based on the interplanetary medium parameters measured in the near-Earth orbits in 1964–1996. The relationships between the IMF azimuthal angle cotangent and plasma velocity are close to linear but strongly differ from one another and from the theoretical relationship for all types of streams. These differences area caused by the magnetic field disturbance on the time scales smaller than a day, and the effect of this disturbance has been studied quantitatively. The effective periods of rotation of the IMF sources on the Sun, depending on the solar cycle phase, have been obtained from the relations between the IMF azimuthal angle cotangent and plasma velocity. During the most part of the solar cycle, the periods of rotation of the IMF sources are close to the period of rotation of the solar equator but abruptly increase to the values typical of the solar circumpolar zones in the years of solar minimums. 相似文献
15.
M. Schüssler 《Annales Geophysicae》1999,17(5):578-582
Two aspects of solar MHD are discussed in relation to the work of the MHD simulation group at KIS. Photospheric magneto-convection, the nonlinear interaction of magnetic field and convection in a strongly stratified, radiating fluid, is a key process of general astrophysical relevance. Comprehensive numerical simulations including radiative transfer have significantly improved our understanding of the processes and have become an important tool for the interpretation of observational data. Examples of field intensification in the solar photosphere (‘convective collapse’) are shown. The second line of research is concerned with the dynamics of flux tubes in the convection zone, which has far-reaching implications for our understanding of the solar dynamo. Simulations indicate that the field strength in the region where the flux is stored before erupting to form sunspot groups is of the order of 105 G, an order of magnitude larger than previous estimates based on equipartition with the kinetic energy of convective flows. 相似文献
16.
M. M. Katsova 《Geomagnetism and Aeronomy》2012,52(7):836-842
The levels of chromospheric and coronal activity of the Sun are compared with new vast observations of late-type stars. The solar chromosphere turned to be more powerful than in the main body of stars and the corona is considerably weakened. A wavelet analysis of activity indices and measurement results for the magnetic field of the Sun as a star was performed for several solar cycles. It was obtained that solar activity in the differential rotation differs from phenomena on less massive K stars with cycles and, in contrast to them, the large-scale magnetic field of the Sun is a regulating factor for active processes. These results can be naturally explained with the assumption that the activity of a star with a given mass depends on the depth of the lower base of the convective zone. This seems to require the development of knowledge about the two-level dynamo and a new approach to studying solar-type activity. 相似文献
17.
A possible mechanism of earthquake triggering by ionizing radiation of solar flares is considered. A theoretical model and results of numerical calculations of disturbance of electric field, electric current, and heat release in lithosphere associated with variation of ionosphere conductivity caused by absorption of ionizing radiation of solar flares are presented. A generation of geomagnetic field disturbances in a range of seconds/tens of seconds is possible as a result of large-scale perturbation of a conductivity of the bottom part of ionosphere in horizontal direction in the presence of external electric field. Amplitude-time characteristics of the geomagnetic disturbance depend upon a perturbation of integral conductivity of ionosphere. Depending on relation between integral Hall and Pedersen conductivities of disturbed ionosphere the oscillating and aperiodic modes of magnetic disturbances may be observed. For strong perturbations of the ionosphere conductivities amplitude of pulsations may obtain ~102 nT. In this case the amplitude of horizontal component of electric field on the Earth surface obtains 0.01 mV/m, electric current density in lithosphere –10–6 A/m2, and the power density of heat release produced by the generated current is 10–7 W/m3. It is shown that the absorption of ionizing radiation of solar flares can result in variations of a density of telluric currents in seismogenic faults comparable with a current density generated in the Earth crust by artificial pulsed power systems (geophysical MHD generator " Pamir-2” and electric pulsed facility " ERGU-600”), which provide regional earthquake triggering and spatiotemporal variation of seismic activity. Therefore, triggering of seismic events is possible not only by man-made pulsed power sources but also by the solar flares. The obtained results may be a physical basis for a novel approach to solve the problem of short-term earthquake prediction based on electromagnetic triggering phenomena. 相似文献
18.
I. A. Bilenko 《Geomagnetism and Aeronomy》2009,49(8):1113-1114
The sources of geomagnetic disturbances during 1999–2003 are discussed. The relation between geomagnetic activity and the
rate of coronal mass ejections (CMEs), their parameters, and the dynamics of solar photospheric magnetic fields is considered.
It is shown that during the reorganization of unipolar regions of the photospheric magnetic field, the number of CMEs increases
and their parameters change. The geomagnetic disturbance level also increases in these periods. 相似文献
19.
A very strong magnetic storm of May 15, 2005, was caused by an interplanetary magnetic cloud that approached the Earths’ orbit. The sheath region of this cloud was characterized by a high solar wind density (～25–30 cm?3) and velocity (～850 km/s) and strong variations (to ～20 nT) in the interplanetary magnetic field (IMF). It has been indicated that an atypical bay-like geomagnetic disturbance was observed during the initial phase of this storm in a large longitudinal region at high latitudes: from the morning to evening sectors of the geomagnetic local time. Increasing in amplitude, the magnetic bay rapidly propagated to the polar cap latitudes up to the geomagnetic pole. An analysis of the global space-temporal dynamics of geomagnetic pulsations in the frequency band 1–6 mHz indicated that most intense oscillations were observed in the morning sector in the region of the equivalent ionospheric current at latitudes of about 72°–76°. The wavelet structure of magnetic pulsations in the polar cap and fluctuations in IMF was generally similar to the maximum at frequencies lower than 4 mHz. This can indicate that waves directly penetrated into the polar cap from the solar wind. 相似文献
20.
The contribution of global magnetospheric oscillations to magnetic disturbance during magnetospheric storms is studied. The
bases of magnetic data from the INTERMAGNET global network in combination with the interplanetary and intramagnetospheric
measurements of the magnetic field and plasma and the sets of the Kp, Dst, and AE indices are used for this purpose. The most favorable conditions in the solar wind and magnetosphere for generation of global
Pc5 have been revealed. The contribution of these oscillations to the variations in the magnetic disturbance level, characterized
by the AE index, has been estimated. The findings confirm that magnetospheric MHD oscillations participate in the processes of energy
income from the solar wind and energy dissipation in the magnetosphere. 相似文献