MPS Seminar: Predicting solar magnetic activity and itsimplications for global dynamo models (N. Singh)

Using the solar surface mode, i.e. the f-mode, we attemptto predict the emergence of active regions (ARs) in the days beforethey can be seen in magnetograms. Our study is motivated by earliernumerical findings of Singh et al. (2014) who showed that, in thepresence of a nonuniform magnetic field which is concentrated a fewscale heights below the surface, the f-mode fans out in the diagnostick-omega diagram at high wavenumbers. Here we exploit this propertyusing data from the Helioseismic and Magnetic Imager aboard theSolar Dynamics Observatory, and show for about six ARs that at large latitudinal wavenumbers (corresponding to horizontal scales of around3000 km), the f-mode displays strengthening about two days prior toAR formation and thus provides a new precursor for AR formation. Iwill also discuss ways to isolate signals from newly forming ARs in acrowded environment where existing ones are expected to pollute theneighbouring patches.The idea that the f-mode is perturbed days before anyvisible magnetic activity occurs on the surface can be important inconstraining dynamo models aiming at understanding the global magnetic activityof the Sun.