Solar Open Magnetic Flux Migration Pattern over Solar Cycles

2019 ◽  
Vol 15 (S354) ◽  
pp. 157-159
Author(s):  
Chia-Hsien Lin ◽  
Guan-Han Huang ◽  
Lou-Chuang Lee
Keyword(s):  
Solar Cycle ◽  
Magnetic Flux ◽  
Solar Observatory ◽  
Migration Pattern ◽  
Polar Regions ◽  
Solar Cycles ◽  
Low Latitude ◽  
Solar Cycle Variation ◽  
Open Magnetic Flux ◽  
Open Flux

AbstractThe objective of this study is to investigate the solar-cycle variation of the areas of solar open magnetic flux regions at different latitudes. The data used in this study are the radial-field synoptic maps from Wilcox Solar Observatory from May 1970 to December 2014, which covers 3.5 solar cycles. Our results reveal a pole-to-pole trans-equatorial migration pattern for both inward and outward open magnetic fluxes. The pattern consists of the open flux regions migrating across the equator, the regions generated at low latitude and migrating poleward, and the regions locally generated at polar regions. The results also indicate the destruction of open flux regions during the migration from pole to equator, and at low latitude regions. The results have been published in Scientific Reports (Huang et al.2017)

Meridional Flow and the Solar Cycle Variation of the Sun’s Open Magnetic Flux

2002 ◽  
Vol 580 (2) ◽  
pp. 1188-1196 ◽  
Author(s):  
Y.‐M. Wang ◽  
N. R. Sheeley, Jr. ◽  
J. Lean
Keyword(s):  
Solar Cycle ◽  
Magnetic Flux ◽  
Meridional Flow ◽  
Solar Cycle Variation ◽  
Cycle Variation ◽  
Open Magnetic Flux

scholarly journals A superposed epoch analysis of auroral evolution during substorm growth, onset and recovery: open magnetic flux control of substorm intensity

2009 ◽  
Vol 27 (2) ◽  
pp. 659-668 ◽  
Author(s):  
S. E. Milan ◽  
A. Grocott ◽  
C. Forsyth ◽  
S. M. Imber ◽  
P. D. Boakes ◽  
...  
Keyword(s):  
Magnetic Flux ◽  
Ring Current ◽  
Low Latitude ◽  
Superposed Epoch Analysis ◽  
Before And After ◽  
Open Magnetic Flux ◽  
Open Flux ◽  
Epoch Analysis ◽  
Proton Aurora ◽  
Current Systems

Abstract. We perform two superposed epoch analyses of the auroral evolution during substorms using the FUV instrument on the Imager for Magnetopause-to-Aurora Global Explorer (IMAGE) spacecraft. The larger of the two studies includes nearly 2000 substorms. We subdivide the substorms by onset latitude, a measure of the open magnetic flux in the magnetosphere, and determine average auroral images before and after substorm onset, for both electron and proton aurora. Our results indicate that substorms are more intense in terms of auroral brightness when the open flux content of the magnetosphere is larger, and that magnetic flux closure is more significant. The increase in auroral brightness at onset is larger for electrons than protons. We also show that there is a dawn-dusk offset in the location of the electron and proton aurora that mirrors the relative locations of the region 1 and region 2 current systems. Superposed epoch analyses of the solar wind, interplanetary magnetic field, and geomagnetic indices for the substorms under study indicate that dayside reconnection is expected to occur at a faster rate prior to low latitude onsets, but also that the ring current is enhanced for these events.

Studying solar-cycle variation of open magnetic flux regions using coronal holes

2018 ◽  
Vol 13 (S340) ◽  
pp. 63-64
Author(s):  
Chia-Hsien Lin ◽  
Guan-Han Huang ◽  
Lou-Chuang Lee
Keyword(s):  
Solar Cycle ◽  
Magnetic Flux ◽  
Solar Physics ◽  
Coronal Holes ◽  
Meridional Flow ◽  
Magnetic Polarity ◽  
Solar Cycle Variation ◽  
Global Magnetic Field ◽  
Magnetic Field Change ◽  
Open Magnetic Flux

AbstractThe process of the magnetic polarity reversal of the Sun has been an important subject in the solar physics. The objective of this study is to investigate how solar global magnetic field change over solar cycle by tracking the migration of open magnetic flux regions. The results show that the open magnetic fluxes migrate from one pole to the other crossing the equator during a solar cycle. The migration rate is approximately 10 m s−1, comparable to meridional flow. The results have been published in Scientific Reports (Huang et al. (2017)).

scholarly journals Aurora and open magnetic flux during isolated substorms, sawteeth, and SMC events

2007 ◽  
Vol 25 (8) ◽  
pp. 1865-1876 ◽  
Author(s):  
A. D. DeJong ◽  
X. Cai ◽  
R. C. Clauer ◽  
J. F. Spann
Keyword(s):  
Magnetic Flux ◽  
Temporal Variations ◽  
Auroral Oval ◽  
Polar Cap ◽  
Expansion Phase ◽  
Magnetospheric Convection ◽  
Open Magnetic Flux ◽  
Open Flux ◽  
The Individual

Abstract. Using Polar UVI LBHl and IMAGE FUV WIC data, we have compared the auroral signatures and polar cap open flux for isolated substorms, sawteeth oscillations, and steady magnetospheric convection (SMC) events. First, a case study of each event type is performed, comparing auroral signatures and open magnetic fluxes to one another. The latitude location of the auroral oval is similar during isolated substorms and SMC events. The auroral intensity during SMC events is similar to that observed during the expansion phase of an isolated substorm. Examination of an individual sawtooth shows that the auroral intensity is much greater than the SMC or isolated substorm events and the auroral oval is displaced equatorward making a larger polar cap. The temporal variations observed during the individual sawtooth are similar to that observed during the isolated substorm, and while the change in polar cap flux measured during the sawtooth is larger, the percent change in flux is similar to that measured during the isolated substorm. These results are confirmed by a statistical analysis of events within these three classes. The results show that the auroral oval measured during individual sawteeth contains a polar cap with, on average, 150% more magnetic flux than the oval measured during isolated substorms or during SMC events. However, both isolated substorms and sawteeth show a 30% decrease in polar cap magnetic flux during the dipolarization (expansion) phase.

Solar cycle variation of magnetic flux emergence

1977 ◽  
Vol 214 ◽  
pp. L141 ◽  
Author(s):  
J. M. Davis ◽  
L. Golub ◽  
A. S. Kreiger
Keyword(s):  
Solar Cycle ◽  
Magnetic Flux ◽  
Flux Emergence ◽  
Solar Cycle Variation ◽  
Cycle Variation

scholarly journals Large scale magnetic helicity fluxes estimated from MDI magnetic synoptic charts

2012 ◽  
Vol 8 (S294) ◽  
pp. 157-158
Author(s):  
Shangbin Yang ◽  
Hongqi Zhang
Keyword(s):  
Solar Cycle ◽  
Magnetic Flux ◽  
Solar Disk ◽  
Large Scale ◽  
Magnetic Helicity ◽  
Local Correlation ◽  
Solar Cycles ◽  
23Rd Solar Cycle ◽  
Term Evolution

AbstractTo investigate the characteristics of large scale and long term evolution of magnetic helicity with solar cycles, we use the method of Local Correlation Tracking (LCT) to estimate the magnetic helicity evolution over the 23rd solar cycle from 1996 to 2009 by using 795 MDI magnetic synoptic charts. The main results are: the hemispheric helicity rule still holds in general, i.e. the large-scale negative (positive) magnetic helicity dominates the northern (southern) hemisphere. However, the large scale magnetic helicity fluxes show the same sign in both hemispheres around 2001 and 2005. The global, large scale magnetic helicity flux over the solar disk changes from negative value at the beginning of the 23rd solar cycle to positive value at the end of the cycle, which also shows the similar trend from the normalized magnetic flux by using the magnetic flux. The net accumulated magnetic helicity is negative in the period between 1996 and 2009.

Solar cycle variation of ionospheric parameters over the low latitude station Hainan, China, during 2002–2012 and its comparison with IRI-2012 model

2017 ◽  
Vol 60 (2) ◽  
pp. 381-395 ◽  
Author(s):  
G.J. Wang ◽  
J.K. Shi ◽  
Z. Wang ◽  
X. Wang ◽  
E. Romanova ◽  
...  
Keyword(s):  
Solar Cycle ◽  
Low Latitude ◽  
Solar Cycle Variation ◽  
Latitude Station ◽  
Cycle Variation

scholarly journals Solar Cycle Variation of Cosmic ray Intensity along with Interplanetary and Solar Wind Plasma Parameters

2008 ◽  
Vol 45 (3) ◽  
pp. 63-68 ◽  
Author(s):  
Rajesh Mishra ◽  
Rekha Agarwal ◽  
Sharad Tiwari
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Solar Cycle ◽  
Interplanetary Magnetic Field ◽  
Cosmic Ray ◽  
Solar Wind Plasma ◽  
Solar Cycles ◽  
Plasma Parameters ◽  
Solar Cycle Variation ◽  
Cosmic Ray Intensity

Solar Cycle Variation of Cosmic ray Intensity along with Interplanetary and Solar Wind Plasma ParametersGalactic cosmic rays are modulated at their propagation in the heliosphere by the effect of the large-scale structure of the interplanetary medium. A comparison of the variations in the cosmic ray intensity data obtained by neutron monitoring stations with those in geomagnetic disturbance, solar wind velocity (V), interplanetary magnetic field (B), and their product (V' B) near the Earth for the period 1964-2004 has been presented so as to establish a possible correlation between them. We used the hourly averaged cosmic ray counts observed with the neutron monitor in Moscow. It is noteworthy that a significant negative correlation has been observed between the interplanetary magnetic field, product (V' B) and cosmic ray intensity during the solar cycles 21 and 22. The solar wind velocity has a good positive correlation with cosmic ray intensity during solar cycle 21, whereas it shows a weak correlation during cycles 20, 22 and 23. The interplanetary magnetic field shows a weak negative correlation with cosmic rays for solar cycle 20, and a good anti-correlation for solar cycles 21-23 with the cosmic ray intensity, which, in turn, shows a good positive correlation with disturbance time index (Dst) during solar cycles 21 and 22, and a weak correlation for cycles 20 and 23.

scholarly journals CORONAL MASS EJECTIONS AND THE SOLAR CYCLE VARIATION OF THE SUN’S OPEN FLUX

2015 ◽  
Vol 809 (2) ◽  
pp. L24 ◽  
Author(s):  
Y.-M. Wang ◽  
N. R. Sheeley, Jr.
Keyword(s):  
Solar Cycle ◽  
Coronal Mass Ejections ◽  
Solar Cycle Variation ◽  
Cycle Variation ◽  
Open Flux

scholarly journals Transport of open magnetic flux between solar polar regions

2009 ◽  
Vol 5 (S264) ◽  
pp. 210-212 ◽  
Author(s):  
Alexei A. Pevtsov ◽  
Valentyna I. Abramenko
Keyword(s):  
Magnetic Flux ◽  
Coronal Hole ◽  
Polar Region ◽  
Equatorial Region ◽  
Polar Regions ◽  
Opposite Hemisphere ◽  
Open Magnetic Flux

AbstractWe present the observations of coronal hole that has originated at the polar hole in one hemisphere, extended to equatorial region, got disconnected and transported across the equator to polar region of opposite hemisphere.

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