Solar-Cycle Variation of Magnetic Helicity in Active Regions

2005 ◽  
Vol 57 (3) ◽  
pp. 481-485 ◽  
Author(s):  
Masaoki Hagino ◽  
Takashi Sakurai
Keyword(s):  
Solar Cycle ◽  
Active Regions ◽  
Magnetic Helicity ◽  
Solar Cycle Variation ◽  
Cycle Variation

scholarly journals Solar cycle variation of helicity characteristics indicated by SP/Hinode

2012 ◽  
Vol 8 (S294) ◽  
pp. 149-150
Author(s):  
Juan Hao ◽  
Mei Zhang
Keyword(s):  
Solar Cycle ◽  
Active Regions ◽  
Field Measurements ◽  
Second Phase ◽  
Solar Cycle Variation ◽  
Cycle Variation ◽  
Phase Cycle ◽  
Solar Cycle 24 ◽  
Cycle 24 ◽  
Weak Fields

AbstractHelicity characteristics in active regions (ARs) are studied, using so far the most accurate vector magnetic field measurements obtained with SP/Hinode. Our sample includes all ARs observed by SP/Hinode, up to June 2012. The sample is divided into three sub-samples: Cycle 23 (from 2006.11 to 2008.06), Cycle 24a (from 2008.10 to 2010.09) and Cycle 24b (from 2010.10 to 2012.06). We confirm our previous findings that the usual hemispheric helicity sign rule is not obeyed in the descending phase of solar cycle 23 and is obeyed in the ascending phase of solar cycle 24. And we find that the second phase of the solar cycle 24 (Cycle 24b) shows an even stronger evidence of the usual hemispheric helicity sign rule than its first phase (Cycle 24a). It is also found that our previous finding that the strong and weak fields possess the opposite helicity signs is not followed in Cycle 24b, whereas it is weakly followed in Cycle 24a and strongly followed in the descending phase of Cycle 23. This means that this rule also has a solar cycle variation, in addition to the solar cycle variation of the usual hemispheric helicity sign rule, and there is a roughly 2-years time delay between the two.

scholarly journals The solar cycle variation of topological structures in the global solar corona

2014 ◽  
Vol 565 ◽  
pp. A44 ◽  
Author(s):  
S. J. Platten ◽  
C. E. Parnell ◽  
A. L. Haynes ◽  
E. R. Priest ◽  
D. H. Mackay
Keyword(s):  
Solar Cycle ◽  
Solar Corona ◽  
Solar Cycle Variation ◽  
Topological Structures ◽  
Cycle Variation

scholarly journals Middle atmosphere response to the solar cycle in irradiance and ionizing particle precipitation

2011 ◽  
Vol 11 (10) ◽  
pp. 5045-5077 ◽  
Author(s):  
K. Semeniuk ◽  
V. I. Fomichev ◽  
J. C. McConnell ◽  
C. Fu ◽  
S. M. L. Melo ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Radiative Forcing ◽  
Climate Model ◽  
Middle Atmosphere ◽  
High Energy ◽  
Galactic Cosmic Rays ◽  
Particle Precipitation ◽  
Solar Cycle Variation ◽  
Cycle Variation ◽  
The Impact

Abstract. The impact of NOx and HOx production by three types of energetic particle precipitation (EPP), auroral zone medium and high energy electrons, solar proton events and galactic cosmic rays on the middle atmosphere is examined using a chemistry climate model. This process study uses ensemble simulations forced by transient EPP derived from observations with one-year repeating sea surface temperatures and fixed chemical boundary conditions for cases with and without solar cycle in irradiance. Our model results show a wintertime polar stratosphere ozone reduction of between 3 and 10 % in agreement with previous studies. EPP is found to modulate the radiative solar cycle effect in the middle atmosphere in a significant way, bringing temperature and ozone variations closer to observed patterns. The Southern Hemisphere polar vortex undergoes an intensification from solar minimum to solar maximum instead of a weakening. This changes the solar cycle variation of the Brewer-Dobson circulation, with a weakening during solar maxima compared to solar minima. In response, the tropical tropopause temperature manifests a statistically significant solar cycle variation resulting in about 4 % more water vapour transported into the lower tropical stratosphere during solar maxima compared to solar minima. This has implications for surface temperature variation due to the associated change in radiative forcing.

scholarly journals Solar cycle variation of interstellar neutral He, Ne, O density and pick-up ions along the Earth's orbit

2016 ◽  
Vol 458 (4) ◽  
pp. 3691-3704 ◽  
Author(s):  
Justyna M. Sokół ◽  
Maciej Bzowski ◽  
Marzena A. Kubiak ◽  
Eberhard Möbius
Keyword(s):  
Solar Cycle ◽  
Solar Cycle Variation ◽  
Cycle Variation
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