排序方式： 共有19条查询结果，搜索用时 15 毫秒
1.
Irina A. Bilenko 《Solar physics》2018,293(7):106
We propose a new model for the magnetic field at different distances from the Sun during different phases of the solar cycle. The model depends on the observed large-scale non-polar (\({\pm}\, 55^{\circ }\)) photospheric magnetic field and on the magnetic field measured at polar regions from \(55^{\circ }\) N to \(90^{\circ }\) N and from \(55^{\circ }\) S to \(90^{\circ }\) S, which are the visible manifestations of cyclic changes in the toroidal and poloidal components of the global magnetic field of the Sun. The modeled magnetic field is determined as the superposition of the non-polar and polar photospheric magnetic field and considers cycle variations. The agreement between the model predictions and magnetic fields derived from direct in situ measurements at different distances from the Sun, obtained with different methods and at different solar activity phases, is quite satisfactory. From a comparison of the magnetic fields as observed and calculated from the model at 1 AU, we conclude that the model magnetic field variations adequately explain the main features of the interplanetary magnetic field (IMF) radial, \(B_{\mathrm{x}}\), component cycle evolution at Earth’s orbit. The modeled magnetic field averaged over a Carrington rotation (CR) correlates with the IMF \(B_{\mathrm{x}}\) component also averaged over a CR at Earth’s orbit with a coefficient of 0.691, while for seven CR-averaged data, the correlation reaches 0.81. The radial profiles of the modeled magnetic field are compared with those of already existing models. In contrast to existing models, ours provides realistic magnetic-field radial distributions over a wide range of heliospheric distances at different cycle phases, taking into account the cycle variations of the solar toroidal and poloidal magnetic fields. The model is a good approximation of the cycle behavior of the magnetic field in the heliosphere. In addition, the decrease in the non-polar and polar photospheric magnetic fields is shown. Furthermore, the magnetic field during solar cycle maxima and minima decreased from Cycle 21 to Cycle 24. This implies that both the toroidal and poloidal components, and therefore the solar global magnetic field, decreased from Cycle 21 to Cycle 24. 相似文献
2.
Astronomy Reports - We consider the events of type II radio bursts (RBII) in the decametric and hectometric ranges from 1 to 16 MHz and the dependence of the parameters of associated coronal mass... 相似文献
3.
I. A. Bilenko 《Geomagnetism and Aeronomy》2016,56(8):978-986
We compare changes in the solar global magnetic field (GMF) given by the distribution of magnetic fields on the source surface and spot activity characterized by Wolf numbers, the number of spots, and their area reflecting the dynamics of local magnetic fields of active regions during cycles 21 to 24 (1976–2015). The results indicate that the changes in the GMF and spot activity have certain differences, both in different cycles generally and in the phases of growth, maximum, and decline in each individual cycle. The maximum and minimum correlations between the GMF and spot activity are observed in cycles 22 and 24, respectively. The maximum correlation is reached in growth phases (cycles 21, 22, and 24) and in the phase of decline (cycle 23), which can be associated with the fact that the phase of decline in cycle 23 is anomalously extended. Almost no correlation between the GMF and spot activity can be found at the phases of the maximum and early beginning of decline in all cycles. This can be associated with structural reorganization and sign change in the GMF. 相似文献
4.
We suggest a new differential method whereby we have detected the separation of a long-duration flare into intervals characterized by different regimes of plasma heating and cooling based on soft X-ray data. The rise phase of the flare is shown to consist of accelerated and decelerated heating regimes compared to an exponential law. Accelerated cooling takes place at the beginning of the decay phase, which is followed by decelerated one. The final part of the flare is a prolonged process of cooling according to a nearly exponential law. 相似文献
5.
Tracing glacier wastage in the Northern Tien Shan (Kyrgyzstan/Central Asia) over the last 40 years 总被引：2，自引：1，他引：1
Peter Niederer Viktor Bilenko Natasha Ershova Hans Hurni Sergeji Yerokhin Daniel Maselli 《Climatic change》2008,86(1-2):227-234
The status and dynamics of glaciers are crucial for agriculture in semiarid parts of Central Asia, since river flow is characterized
by major runoff in spring and summer, supplied by glacier- and snowmelt. Ideally, this coincides with the critical period
of water demand for irrigation. The present study shows a clear trend in glacier retreat between 1963 and 2000 in the Sokoluk
watershed, a catchment of the Northern Tien Shan mountain range in Kyrgyzstan. The overall area loss of 28% observed for the
period 1963–2000, and a clear acceleration of wastage since the 1980s, correlate with the results of previous studies in other
regions of the Tien Shan as well as the Alps. In particular, glaciers smaller than 0.5 km2 have exhibited this phenomenon most starkly. While they registered a medium decrease of only 9.1% for 1963–1986, they lost
41.5% of their surface area between 1986 and 2000. Furthermore, a general increase in the minimum glacier elevation of 78 m
has been observed over the last three decades. This corresponds to about one-third of the entire retreat of the minimum glacier
elevation in the Northern Tien Shan since the Little Ice Age maximum. 相似文献
6.
Geomagnetism and Aeronomy - Regularities of the spatial and temporal variation in the plasma parameters of the interplanetary medium in solar cycles 21–24 are studied based on the data from... 相似文献
7.
Geomagnetism and Aeronomy - The influence of cycle changes in the polar and nonpolar photospheric magnetic fields on variations in the interplanetary magnetic field (IMF) and the solar wind... 相似文献
8.
Irina A. Bilenko 《Solar physics》2004,221(2):261-282
The longitudinal distribution of coronal holes has been analyzed for the time interval 1976–2002. Coronal holes don't seem
to be randomly distributed. The cluster structure has been revealed in the time—space organization of coronal hole distribution.
The complexity and lifetime of clusters depend on the solar cycle phase. The comparison of active region and coronal hole
cluster structures shows that some coronal hole clusters as well as active region ones occur almost simultaneously in both
hemispheres, some clusters in the north or in the south hemisphere only. Some coronal hole clusters coincide with the active
region clusters and some do not coincide. They reflect the large-scale solar magnetic field distribution. 相似文献
9.
I. A. Bilenko 《Geomagnetism and Aeronomy》2012,52(8):1005-1014
This paper investigates the dependence of the observed coronal mass ejections and their parameters on evolutionary changes in the global solar magnetic field at different phases of solar cycles 23?C24. Four periods in the evolution of the solar cycle are identified, depending on the dominance ratio of the sectoral and zonal magnetic field structures. The parameters of coronal mass ejections observed during these periods are analyzed. The evolving structure in the global magnetic field is identified, and its influence on coronal mass ejections is examined. 相似文献
10.
Current sheet (CS) creation and energy accumulation above the NOAA 9077 active region have been numerically simulated. The magnetic spots are approximated by vertical dipoles placed under the photosphere, and the system of resistive 3D MHD equations is solved for compressible plasma with anisotropic thermal conduction. Two neutral magnetic lines are present in the corona above the NOAA 9077 active region, and a vertical CS emerges in the vicinity of one of them. The energy accumulated in this CS is about 5×1032 erg. The j×B/c force in it accelerates plasma upward. The other neutral line is not suitable for CS creation. 相似文献