Helicity on the Sun: What is it good for anyway? Slide 1 of 10830

Slide 2 of Helicity has done extremely well from present (much better than my 401K!)

Kusano et al (2002) had studied helicity and energy flow into photosphere in AR8100, Nov. 2-5, Helicity injection due to vertical flows, 6 x Wb 2, comparable with helicity injection due to horizontal flows -Energy injected into corona due to helicity injection, 2 x J – larger than emitted by all flares during same period

Absolute value of the magnetic helicity induced by photospheric horizontal motions accumulated during the flaring time interval vs. the corresponding GOES X-ray flux integrated over the flaring time. Moon et al, 2008, NOAA Impulsive helicity injections episodes coinciding with C, M-class flares. -Both positive and negative helicity in injected by shear motions. - The flare X-ray flux integrated over the X-ray emission time strongly correlates with the magnetic helicity injected during the flaring interval. Park et al 2008; 7 active regions - All major flares were preceded by a significant helicity accumulation, (1.8-16) x Mx 2 over 0.5 to a few days. - average helicity change rate in the first phase shows strong correlation with the time- integrated soft X-ray flux Park et al 2010; 378 ARs - (91 large ARs), difference in the magnetic helicity injection rate between flaring ARs and nonflaring ARs by a factor of 2 - GOES C-flare-productive probability as a function of helicity injection displays a sharp boundary between flare-productive ARs and flare-quiet ones.

Komm & Hill, 2009, 1009 ARs

Reiner, et al NHGV (Normalized Helicity Gradient Variance) is effective at separating flaring and non-flaring active regions and even separates among C-, M-, and X-class flare producing regions. -It also provides advance notice of flare occurrence, as it increases 2–3 days before the flare occurs.

You might not need helicity for a flare, but it helps.