Monthly Archives: April 2014

13. “G-nodes” Offer a New Way to Peek into the Sun’s Interior

Contributed by Scott McIntosh. Posted on April 30, 2014

We have seen that the quiescent photospheric magnetic field is composed of multiple connective scales. The observed scales range from a few megameters to those that are 100 –250 Mm in scale. We expect that the latter of these scales belongs to a spatially large, deep and hence slowly overturning convective flow — one that possibly reaches to the bottom of convection zone.

12. Analyzing 60,000 Supergranules to Determine their Subsurface Flow Profile

Contributed by Tom Duvall. Posted on April 29, 2014

Analysis of a large number of supergranules observed with HMI and simulations with a convectively stabilized solar model imply that the average supergranular cell has a peak upflow of 240 m s-1 at a depth of 2.3 Mm and a corresponding peak outward horizontal flow of 700 m s-1 at a depth of 1.6 Mm.

11. The long-term trend in magnetic fields of sunspot umbrae

Contributed by Fraser Watson. Posted on April 25, 2014

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.