Tag Archives: solar cycle
72. The Magnetic Mid-life Crisis of the Sun
58. Signs of Cycle 25 Seen in the Surface Toroidal Field
52. F10.7 Microwave Flux Matches the Total Disk Unsigned Magnetic Flux from MDI and HMI
41. The Cause of the Weak Solar Cycle 24
39. Solar Cycle Variation of the Inter-Network Magnetic Field
32. The Polar Field Reversal of Solar Cycle 24
15. Potential field source surface “breathes” over the course of the solar cycle
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.