scholarly journals Solar cycle-dependent helicity transport by magnetic clouds

2005 ◽  
Vol 110 (A8) ◽  
Author(s):  
B. J. Lynch ◽  
J. R. Gruesbeck ◽  
T. H. Zurbuchen ◽  
S. K. Antiochos
Keyword(s):  
Solar Cycle ◽  
Magnetic Clouds ◽  
Cycle Dependent

scholarly journals Solar cycle evolution of the structure of magnetic clouds in the inner heliosphere

1998 ◽  
Vol 25 (15) ◽  
pp. 2959-2962 ◽  
Author(s):  
T. Mulligan ◽  
C. T. Russell ◽  
J. G. Luhmann
Keyword(s):  
Solar Cycle ◽  
Magnetic Clouds ◽  
Inner Heliosphere

Geoeffectiveness of magnetic clouds occurred during solar cycle 23

2010 ◽  
Vol 58 (5) ◽  
pp. 741-748 ◽  
Author(s):  
Santosh Kumar ◽  
Amita Raizada
Keyword(s):  
Solar Cycle ◽  
Magnetic Clouds ◽  
Solar Cycle 23

Confirmation of solar cycle-dependent intermediate-degree p-mode frequency shifts

1993 ◽  
Vol 406 ◽  
pp. 714 ◽  
Author(s):  
Edward J., Jr. Rhodes ◽  
Alessandro Cacciani ◽  
Sylvain G. Korzennik ◽  
Roger K. Ulrich
Keyword(s):  
Solar Cycle ◽  
Mode Frequency ◽  
Frequency Shifts ◽  
Intermediate Degree ◽  
Cycle Dependent

Solar sources and geospace consequences of interplanetary magnetic clouds observed during solar cycle 23

2008 ◽  
Vol 70 (2-4) ◽  
pp. 245-253 ◽  
Author(s):  
N. Gopalswamy ◽  
S. Akiyama ◽  
S. Yashiro ◽  
G. Michalek ◽  
R.P. Lepping
Keyword(s):  
Solar Cycle ◽  
Magnetic Clouds ◽  
Solar Cycle 23

scholarly journals Solar cycle dependent characteristics of the equatorial blanketing E<sub><i>s</i></sub> layers and associated irregularities

2006 ◽  
Vol 24 (11) ◽  
pp. 2931-2947 ◽  
Author(s):  
C. V. Devasia ◽  
V. Sreeja ◽  
S. Ravindran
Keyword(s):  
Solar Activity ◽  
Solar Cycle ◽  
Electric Field ◽  
Solar Minimum ◽  
Solar Maximum ◽  
Dominant Role ◽  
Onset Time ◽  
Vhf Radar ◽  
Cycle Dependent ◽  
June July

Abstract. The occurrence of blanketing type Es (Esb) layers and associated E-region irregularities over the magnetic equatorial location of Trivandrum (8.5° N; 77° E; dip ~0.5°) during the summer solstitial months of May, June, July and August has been investigated in detail for the period 1986–2000 to bring out the variabilities in their characteristics with the solar cycle changes. The study has been made using the ionosonde and magnetometer data of Trivandrum from 1986–2000 along with the available data from the 54.95 MHz VHF backscatter radar at Trivandrum for the period 1995–2000. The appearance of blanketing Es layers during these months is observed to be mostly in association with the occurrence of afternoon Counter Electrojet (CEJ) events. The physical process leading to the occurrence of a CEJ event is mainly controlled by the nature of the prevailing electro dynamical/neutral dynamical conditions before the event. Hence it is natural that the Esb layer characteristics like the frequency of occurrence, onset time, intensity, nature of gradients in its top and bottom sides etc are also affected by the nature of the background electro dynamical /neutral dynamical processes which in turn are strongly controlled by the solar activity changes. The occurrence of Esb layers during the solstitial months is found to show very strong solar activity dependence with the occurrence frequency being very large during the solar minimum years and very low during solar maximum years. The intensity of the VHF radar backscattered signals from the Esb irregularities is observed to be controlled by the relative roles of the direction and magnitude of the prevailing vertical polarization electric field and the vertical electron density gradient of the prevailing Esb layer depending on the phase of the solar cycle. The gradient of the Esb layer shows a more dominant role in the generation of gradient instabilities during solar minimum periods while it is the electric field that has a more dominant role during solar maximum periods.

scholarly journals Magnetic Helicity in Sigmoids, Coronal Mass Ejections and Magnetic Clouds

2005 ◽  
Vol 13 ◽  
pp. 105-108
Author(s):  
D. M. Rust
Keyword(s):  
Solar Cycle ◽  
Coronal Mass Ejections ◽  
Magnetic Clouds ◽  
Magnetic Helicity ◽  
The Sun ◽  
X Ray ◽  
The North ◽  
Negative Helicity ◽  
Flux Ropes ◽  
Lines Of Evidence

AbstractSigmoids, coronal mass ejections (CMEs) and magnetic clouds (MCs) all show signatures of twisted and writhing magnetic fields. CMEs are often associated with MCs, whose fields are regularly mapped with sensitive magnetometers. These measurements reveal that MC fields are helical, and each MC carries magnetic helicity away from the sun. It is more difficult to determine the magnetic helicity of the corresponding features on the sun. This presentation surveys recent work on helicity in solar features, focusing especially on the interpretation of sigmoids, which are S-shaped, bright features seen in images from the Yohkoh soft X-ray telescope. Several lines of evidence indicate that sigmoids are twisted and writhing flux ropes that erupt as components of CMEs. CMEs may be initiated by MHD-instable flux ropes. The fact that the ejected flux ropes carry off a large amount of positive helicity from the south and negative helicity from the north each solar cycle implies an equal, compensating flow of helicity through the sun’s equatorial plane.

Sign in / Sign up

Export Citation Format

Share Document