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31.
The large-scale configuration of spot groups was investigated within a complex proton region. The probability of occurrence of accompanying spot groups (satellites) was studied according to the classification types, the direction of their occurrence, and the distance with respect to the proton spot group. The results obtained indicate that the condition for the generation of a proton spot group will not only rest with the known small-scale interaction of a few magnetic systems and the creation of a single group, but also with the existence of satellites in the neighbourhood of the proton group up to a distance of several tens of degrees.On leave from the Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN), c/o Academgorodok, Moscow Region, U.S.S.R. 相似文献
32.
A model treating a solar coronal hole as an axially symmetrical magnetic formation that is in equilibrium with the surrounding
medium is proposed. The model is applicable in the lower corona (to heights of the order of several hundreds of Mm), where
the influence of the solar-wind outflow on the state of the system can still be neglected. The magnetic field of the coronal
hole is comprised of a relatively weak open flux that varies with height, which extends into interplanetary space, and a closed
field, whose flux closes at the chromosphere near the coronal hole. Simple analytical formulas are obtained, which demonstrate
for a given equilibrium configuration of the plasma and field the main effect of interest—the lowering of the temperature
and density of the gas in the coronal hole compared to their values in the corona at the same geometric height. In particular,
it is shown that, at heights of several tens of Mm, the temperature and density of the plasma in the coronal hole are roughly
half the corresponding values at the same height in the corona, if the cross-sectional radius of the hole exceeds the scale
height in the corona by roughly a factor of 1.5: R
h
≈ 1.5H(T
0). In the special case when R
h
≈ H(T
0), the plasma temperature in the hole is equal to the coronal temperature, and the darkening of the coronal hole is due only
to an appreciable reduction of the plasma density in the hole, compared to the coronal density. An analogy of the properties
of coronal holes and sunspots is discussed, based on the similarity of the magnetic structures of these formations. In spite
of the fundamental difference in the mechanisms for energy transport in coronal holes and sunspots, the equilibrium distributions
of the plasma parameters in these formations are determined only by the magnetic and gravitational forces, giving rise to
a number of common properties, due to their similar magnetic structures. 相似文献
33.
The relevance of the occurrence rate and location of CME events to two main systems (giant and supergiant) of the large-scale solar magnetic field structure has been investigated. The clustering of CME events and solar flares toward the neutral line of the global field system (neutral line of the source surface field) corroborates the finding by Hundhausen that CME locations track the heliomagnetic equator. A good correlation has been revealed between the CME occurrence rate and variations of the index of the effective solar multipole, that characterizes the typical scale of the global solar magnetic field. The CME rate exhibits sharp jumps/decreases when the index of the effective solar multipole passes through n=4. The observations of X-ray 'blow-out' effects have been analyzed as probable manifestations of CMEs on the disk and have been compared with the large-scale magnetic field structure. As shown by the analysis, the X-ray arcades straddle the neutral line and occur, or at least tend to occur, where the neutral line exhibits a sharp bend. A conclusion is made that CME events are caused by interaction of two large-scale field systems, one of them (the global field system) determining the location of CMEs and another (the system of closed magnetic fields) their occurrence rate. 相似文献
34.
Experiments based on multi-source radio occultation measurements of the circumsolar plasma at R∼4.0−70R
S were carried out during 1997 – 2008 to locate the inner boundary of the solar-wind transonic transition region, R
in. The data obtained were used to correlate the solar-wind stream structure and magnetic fields on the source surface (R=2.5R
S) in the solar corona. The method of the investigation is based on the analysis of the dependence R
in=F(|B
R|) in the correlation diagrams, where R
in is the inner boundary of the solar-wind transition region and |B
R| is the intensity of the magnetic field at the source surface. On such diagrams, the solar wind is resolved into discrete
branches, streams of different types. The analysis of the stream types using a continuous series of data from 1997 to 2008
allowed us to propose a physical criterion for delimiting the epochs in the current activity cycle. 相似文献
35.
Makarov V.I. Tlatov A.G. CALLEBaUT D.K. Obridko V.N. Shelting B.D. 《Solar physics》2001,198(2):409-421
Hα magnetic synoptic charts of the Sun are processed for 1915–1999 and the spherical harmonics are calculated. It is shown
that the polarity distribution of the magnetic field on Hα charts is similar to the polarity distribution of the Stanford
magnetic field observations during 1975–1999. The index of activity of the large-scale magnetic field A(t), representing the sum of the intensities of dipole and octupole components, is introduced. It is shown that the cycle of
the large-scale magnetic field of the Sun precedes on the average by 5.5 years the sunspot activity cycle, W(t). This means that the weak large-scale magnetic fields of the Sun do not result from decay and diffusion of strong fields
from active regions as it is supposed in all modern theories of the solar cycle. On the basis of the new data the intensity
of the current solar cycle 23 is predicted and some aspects of the theory of the solar cycle are discussed. 相似文献
36.
The rotation characteristics of large-scale (global) magnetic fields (GMF) and their relation to the activity of local fields (LMF) are studied over a long time interval (1915–1996). The main results are as follows. The GMF rotation rates and LMF activity vary in anticorrelation. Both variations have similar periods (11 years and a quasi-secular period of about 55–60 years), but are shifted relative to each other by half an 11-year cycle. Therefore, (1) the GMF rotation rate increases at the minimum of the 11-year cycle of LMF activity. (2) The GMF rotation rate is faster in the less active hemisphere. (3) The GMF rotation period slows down at the maximum of the secular LMF activity (cycles 18 and 19). 相似文献
37.
Observations of ten solar eclipses (1973–1999) enabled us to reveal and describe mutual relations between the white-light corona structures (e.g., global coronal forms and most conspicuous coronal features, such as helmet streamers and coronal holes) and the coronal magnetic field strength and topology. The magnetic field strength and topology were extrapolated from the photospheric data under the current-free assumption. In spite of this simplification the found correspondence between the white-light corona structure and magnetic field organization strongly suggests a governing role of the field in the appearance and evolution of local and global structures. Our analysis shows that the study of white-light corona structures over a long period of time can provide valuable information on the magnetic field cyclic variations. This is particularly important for the epoch when the corresponding measurements of the photospheric magnetic field are absent. 相似文献
38.
SOHO/MDI magnetograms have been used to analyze the longitude distribution of the squared solar magnetic field 〈B
2〉 in the activity cycle no. 23. The energy of the magnetic field (〈B
2〉) is shown to change with longitude. However, these variations hardly fit the concept of active longitudes. In the epochs
of high solar activity, one can readily see a relationship between longitude variations of the medium-strong ((|B| > 50 G or |B| > 100 G) and relatively weak (|B| ≤ 50 G or |B| ≤ 100 G) fields at all latitudes. In other periods, this relationship is revealed mainly at the latitudes not higher than
30°. The background fields (|B| ≤ 25 G) also display longitude variations, which are, however, not related to those of the strong fields. This makes us
think that the fields of solar activity are rather inclusions to the general field than the source of the latter. 相似文献
39.
A new concept of “Global Complexes of Activity” on the Sun is presented, which brings together objects associated with both global and local fields in a single framework. Activity complexes have traditionally been identified purely from observations of active regions. We show here that a global complex also includes coronal holes and active regions. Our analysis is based on a large dataset on magnetic fields on various scales, SOHO/MDI observations of active regions and magnetic fields, and UV observations of coronal holes. It is shown that the evolution of coronal holes and active regions are parts of a single process. The relationships between the fields on different scales during the generation of the cycle is discussed. 相似文献
40.
V. A. Ozheredov T. K. Breus V. N. Obridko 《Izvestiya Atmospheric and Oceanic Physics》2012,48(7):706-716
As follows from the statement of the Third Official Solar Cycle 24 Prediction Panel created by the National Aeronautics and Space Administration (NASA), the National Oceanic and Atmospheric Administration (NOAA), and the International Space Environment Service (ISES) based on the results of an analysis of many solar cycle 24 predictions, there has been no consensus on the amplitude and time of the maximum. There are two different scenarios: 90 units and August 2012 or 140 units and October 2011. The aim of our study is to revise the solar cycle 24 predictions by a comparative analysis of data obtained by three different methods: the singular spectral method, the nonlinear neural-based method, and the precursor method. As a precursor for solar cycle 24, we used the dynamics of the solar magnetic fields forming solar spots with Wolf numbers Rz. According to the prediction on the basis of the neural-based approach, it was established that the maximum of solar cycle 24 is expected to be 70. The precursor method predicted 50 units for the amplitude and April of 2012 for the time of the maximum. In view of the fact that the data used in the precursor method were averaged over 4.4 years, the amplitude of the maximum can be 20–30% larger (i.e., around 60–70 units), which is close to the values predicted by the neural-based method. The protracted minimum of solar cycle 23 and predicted low values of the maximum of solar cycle 24 are reminiscent of the historical Dalton minimum. 相似文献