Fredagskollokvium: Observing MHD waves in strong magnetic field regions in the solar atmosphere

The conversion of acoustic waves into MHD waves by strong magnetic fields occurs mainly in the sub-photospheric layers. In the solar chromosphere and transition region, we see impressive umbral flashes and running penumbral waves. The photospheric signatures of MHD waves are weak, probably due to low amplitudes at the equipartion level (Alfvén speed=sound speed) where mode-mixing occurs.  I've wanted to detect an unambiguous 𝛿B associated with MHD waves for 20 years, although the uncertainties in the quantities derived from vector polarimetric inversions coupled with small amplitudes makes it, perhaps, an impossible task. I present results from coordinated observations between three space-based telescopes: Hinode SOT/SP, IRIS and SDO/HMI in which we analyze time series for a couple of sunspots to examine the oscillatory power and phase relations between various observable quantities.