The relative importances of solar type iv radio bursts and flare-site magnetic field orientations as predictors of geomagnetic activity

The claim by Pudovkin and his co-workers that the geomagnetic effects of a solar flare are controlled almost exclusively by the direction of the large scale magnetic field at the flare site is in apparent conflict with the well established correlation between flares with type IV radio bursts and subsequent geomagnetic storms. We examine the claims of Pudovkin et al., and show that while the direction of the magnetic field is important in determining the geomagnetic effect of a flare, it is not as important as an accompanying type IV burst.