Measuring coronal magnetic fields with remote sensing observations of   shock waves
  Recent works demonstrated that remote sensing observations of shock waves propagating into the corona and associated with major solar eruptions can be used to derive the strength of coronal magnetic fields met by the shock over a very large interval of heliocentric distances and latitudes. This opinion article will summarize most recent results obtained on this topic and will discuss the weaknesses and strengths of these techniques to open a constructive discussion with the scientific community. 
Alessandro Bemporad, Roberto Susino, Federica Frassati, Silvano   Fineschi
astro-ph.SR