101. Solar Open Flux Migration from Pole to Pole: Magnetic Field Reversal
Long-term migration of the Sun’s open magnetic flux is studied, and its relation with the sunspot numbers is discussed.
Tag Archives: solar cycle
98. Solar-Cycle Variations of Meridional Flows in the Solar Convection Zone with Helioseismic Methods
Meridional flows during the solar minimum and maximum years are derived using 14 years of SOHO/MDI data. The flows changed significantly from the minimum to the maximum, and major changes were associated with the active latitudes.
72. The Magnetic Mid-life Crisis of the Sun
Recent discoveries suggest that Sun-like stars experience a fundamental shift in their rotation and magnetism around middle-age. We have now identified this transition in the best available data on stellar cycles.
58. Signs of Cycle 25 Seen in the Surface Toroidal Field
Using a combination of the magnetograms, we find signs of the beginning of the 25th cycle from both HMI and WSO by calculating the inclination angles determined from the variation in line of sight field during a disk passage.
52. F10.7 Microwave Flux Matches the Total Disk Unsigned Magnetic Flux from MDI and HMI
The F10.7 microwave flux shows remarkabke agreement with the unsigned magnetic flux from MDI and HMI over the past 20 years, attesting to the accuracy and significance of both.
41. The Cause of the Weak Solar Cycle 24
Surface flux transport model suggests that the weak Cycle 24 is mainly caused by a number of bigger bipolar regions emerging at low latitudes with a “wrong” north-south orientation.
39. Solar Cycle Variation of the Inter-Network Magnetic Field
Solar inter-network magnetic field, the weakest component of the solar magnetism, seems to be invariant at ~10 G from the minimum to the maximum phase of Cycle 24. This suggests a possible origin of small-scale, local dynamo.
32. The Polar Field Reversal of Solar Cycle 24
HMI observations reveal a slow, north-south asymmetric polar magnetic field reversal. Cycle 24 has been weak; an even weaker Cycle 25 seems probable.
15. Potential field source surface “breathes” over the course of the solar cycle
Our results show that raising the source surface height 15-30% during solar minimum (depending on the model used) better reproduces the observed IMF open flux from OMNI. We used two different PFSS models and the MDI/HMI magnetograms as input.
11. The long-term trend in magnetic fields of sunspot umbrae
I investigate the possible long term decrease in umbral magnetic field strengths from 1998-2006. Whereas a decrease of 800 Gauss in umbral magnetic fields has been reported between 1998 and 2012, the HMI and MDI data indicate a decrease of only around 300 Gauss. The continuing availability of the excellent HMI data set will allow us to continue to refine this study as solar cycle 24 evolves.