Solar flares and solar subphotospheric vorticity

Abstract

We explore the relation between surface magnetic flux of the sun and subsurface flow vorticity for flaring and nonflaring solar active regions. For this purpose, we use a data set consisting of 1009 active regions, including the vorticity measurements of their subsurface flows derived from high‐resolution global oscillation network group (GONG) helioseismology data and the corresponding X‐ray flare data from the geostationary operation environmental satellite (GOES). Using quantities averaged over the disk passage of active regions, we find that, while there is a considerable spread of the flux and vorticity values, they are more or less linearly related. We distinguish the level of flare activity by X‐ray flare class and find that large flux or large vorticity values are sufficient for an active region to produce low‐intensity C‐class flares. Active regions that produce high‐intensity X‐class flares are characterized by large values of both flux and vorticity. Active regions that produce M‐class flares of intermediate intensity are characterized by large vorticity values. The inclusion of solar subsurface vorticity thus helps to distinguish between flaring and nonflaring active regions.