scholarly journals Dipole Field, Sunspot Cycle and Solar Dynamo

1993 ◽  
Vol 157 ◽  
pp. 97-106
Author(s):  
P.A. Simon ◽  
J.P. Legrand
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Solar Magnetic Field ◽  
Interplanetary Medium ◽  
Sunspot Cycle ◽  
Dipole Field ◽  
Solar Dynamo ◽  
Dipole Component ◽  
Two Component

From the analysis of a series of data concerning phenomena taking place in the high corona, in the interplanetary medium and in the magnetosphere, we came to the conclusion that we have to take into consideration a two-component solar cycle in which, with a 5–6 yr delay, the cycle of the dipole component of the solar magnetic field and the following sunspot cycle are closely correlated. In order to show the new mechanisms to incorporate into a model of a two-component solar cycle, we discuss several other relevant solar data.

scholarly journals GLOBAL DISTURBANCE OF EARTH’S MAGNETOSPHERE AND ITS CONNECTION WITH SPACE WEATHER

2020 ◽  
Vol 6 (1) ◽  
pp. 51-62
Author(s):  
Nadezhda Kurazhkovskaya
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Space Weather ◽  
Interplanetary Medium ◽  
Dynamic Pressure ◽  
Annual Number ◽  
Solar Cycles ◽  
Winter Solstice ◽  
Solar Cycle 24 ◽  
Cycle 24

This paper deals with extreme conditions of the global magnetosphere disturbance: very quiet and greatly disturbed, and their relationship with interplanetary medium parameters. The degree of global magnetosphere disturbance was estimated from the monthly and annual number of magnetically quiet and magnetically disturbed days. The cyclic and seasonal distributions of magnetically quiet and disturbed days were compared, and their relationship with interplanetary medium parameters in solar cycles 20–24 was analyzed. Magnetically quiet days are shown to be mainly observed at the ascending phase of solar activity and during the winter solstice season. Magnetically disturbed days dominate at the descending phase of the solar cycle and during the equinox season. An anomalously large increase in the number of quiet days was found in solar cycle 24 as compared to previous cycles. It has been established that the cyclic variation in the annual number of quiet and disturbed days is determined by the behavior and magnitude of the speed, temperature, dynamic pressure of solar wind plasma and the interplanetary magnetic field modulus. The detected burst in the number of quiet days during the ascending phase of solar cycle 24 is assumed to reflect internal processes on the Sun and related changes in interplanetary medium parameters. The patterns of cyclical and seasonal variation in the number of magnetically quiet and disturbed days and their relationship with the solar wind parameters can be used to predict space weather.

scholarly journals Magnetic clouds along the solar cycle: expansion and magnetic helicity

2011 ◽  
Vol 7 (S286) ◽  
pp. 139-148 ◽  
Author(s):  
Sergio Dasso ◽  
Pascal Démoulin ◽  
Adriana M. Gulisano
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Magnetic Flux ◽  
Interplanetary Medium ◽  
Wind Pressure ◽  
Magnetic Clouds ◽  
Magnetic Helicity ◽  
The Sun ◽  
Mean Velocity ◽  
Plasma Properties

AbstractMagnetic clouds (MCs) are objects of extreme importance in the heliosphere. They have a major role on releasing magnetic helicity from the Sun (with crucial consequences on the solar dynamo), they are the hugest transient object in the interplanetary medium, and the main actors for the Sun-Earth coupling. The comparison between models and observations is beginning to clarify several open questions on MCs, such as their internal magnetic configuration and their interaction with the ambient solar wind. Due to the decay of the solar wind pressure with the distance to the Sun, MCs are typically in expansion. However, their detailed and local expansion properties depend on their environment plasma properties. On the other hand, while it is well known that the solar cycle determines several properties of the heliosphere, the effects of the cycle on MC properties are not so well understood. In this work we review two major properties of MCs: (i) their expansion, and (ii) the magnetic flux and helicity that they transport through the interplanetary medium. We find that the amount of magnetic flux and helicity released via MCs during the last solar minimum (years 2007-2009) was significantly lower than in the previous one (years 1995-1997). Moreover, both MC size and mean velocity are in phase with the solar cycle while the expansion rate is weakly variable and has no relationship with the cycle.

scholarly journals GLOBAL DISTURBANCE OF EARTH’S MAGNETOSPHERE AND ITS CONNECTION WITH SPACE WEATHER

2020 ◽  
Vol 6 (1) ◽  
pp. 41-49 ◽  
Author(s):  
Nadezhda Kurazhkovskaya
Keyword(s):  
Solar Wind ◽  
Solar Cycle ◽  
Space Weather ◽  
Interplanetary Medium ◽  
Dynamic Pressure ◽  
Annual Number ◽  
Solar Cycles ◽  
Winter Solstice ◽  
Solar Cycle 24 ◽  
Cycle 24

This paper deals with extreme conditions of the global magnetosphere disturbance: very quiet and greatly disturbed, and their relationship with interplanetary medium parameters. The degree of global magnetosphere disturbance was estimated from the monthly and annual number of magnetically quiet and magnetically disturbed days. The cyclic and seasonal distributions of magnetically quiet and disturbed days were compared, and their relationship with interplanetary medium parameters in solar cycles 20–24 was analyzed. Magnetically quiet days are shown to be mainly observed at the ascending phase of solar activity and during the winter solstice season. Magnetically disturbed days dominate at the descending phase of the solar cycle and during the equinox season. An anomalously large increase in the number of quiet days was found in solar cycle 24 as compared to previous cycles. It has been established that the cyclic variation in the annual number of quiet and disturbed days is determined by the behavior and magnitude of the speed, temperature, dynamic pressure of solar wind plasma and the interplanetary magnetic field modulus. The detected burst in the number of quiet days during the ascending phase of solar cycle 24 is assumed to reflect internal processes on the Sun and related changes in interplanetary medium parameters. The patterns of cyclical and seasonal variation in the number of magnetically quiet and disturbed days and their relationship with the solar wind parameters can be used to predict space weather.

scholarly journals Relating 27-Day Averages of Solar, Interplanetary Medium Parameters, and Geomagnetic Activity Proxies in Solar Cycle 24

Solar Physics ◽  
2021 ◽  
Vol 296 (7) ◽  
Author(s):  
Yvelice Castillo ◽  
Maria Alexandra Pais ◽  
João Fernandes ◽  
Paulo Ribeiro ◽  
Anna L. Morozova ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Geomagnetic Activity ◽  
Interplanetary Medium ◽  
Solar Cycle 24 ◽  
Cycle 24

Calculated Coronal Magnetic Fields and Their Comparison with the Coronal Structures as Observed during Five Solar Eclipses

1994 ◽  
Vol 144 ◽  
pp. 559-564
Author(s):  
P. Ambrož ◽  
J. Sýkora
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Coronal Magnetic Field ◽  
Coronal Magnetic Fields ◽  
Solar Eclipses ◽  
Coronal Structures

AbstractWe were successful in observing the solar corona during five solar eclipses (1973-1991). For the eclipse days the coronal magnetic field was calculated by extrapolation from the photosphere. Comparison of the observed and calculated coronal structures is carried out and some peculiarities of this comparison, related to the different phases of the solar cycle, are presented.

The Hemispheric Sign Rule of Current Helicity during the Rising Phase of Cycle 23

2000 ◽  
Vol 179 ◽  
pp. 303-306
Author(s):  
S. D. Bao ◽  
G. X. Ai ◽  
H. Q. Zhang
Keyword(s):  
Solar Cycle ◽  
Southern Hemisphere ◽  
Northern Hemisphere ◽  
Active Regions ◽  
Hemispheric Preference ◽  
Current Helicity

AbstractWe compute the signs of two different current helicity parameters (i.e., αbestandHc) for 87 active regions during the rise of cycle 23. The results indicate that 59% of the active regions in the northern hemisphere have negative αbestand 65% in the southern hemisphere have positive. This is consistent with that of the cycle 22. However, the helicity parameterHcshows a weaker opposite hemispheric preference in the new solar cycle. Possible reasons are discussed.

Prominences and Solar Activity

1979 ◽  
Vol 44 ◽  
pp. 357-372
Author(s):  
Z. Švestka
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
List Type ◽  
Type Number ◽  
Flare Loops ◽  
Filament Activation

The following subjects were discussed:(1)Filament activation(2)Post-flare loops.(3)Surges and sprays.(4)Coronal transients.(5)Disk vs. limb observations.(6)Solar cycle variations of prominence occurrence.(7)Active prominences patrol service.Of all these items, (1) and (2) were discussed in most detail and we also pay most attention to them in this report. Items (3) and (4) did not bring anything new when compared with the earlier invited presentations given by RUST and ZIRIN and therefore, we omit them.

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