Coronal Magnetism: Difficulties and Prospects

Prospects for advances in understanding the properties of the coronal magnetic field are discussed. A new generation of ground-based instrumentation presents possibilities of improved direct measurements of the field (the Advanced Technology Solar Telescope: ATST) and its inference from radio observations (the Frequency Agile Solar Radiotelescope: FASR). The latter in particular promises major advances in determining the structure of the strong magnetic fields present in active regions. Interpreting observations of coronal oscillations using MHD wave models to infer a magnetic field strength has become popular. While limb observations yield field strengths compatible with those obtained from infrared spectroscopy, disc observations yield values that seem on the low side, suggesting the need for a programme of forward modelling with realistic global magnetic fields. Global magnetic field models can now provide information on the field in the corona, and towards the Earth through the solar wind. Major challenges for such modelling are the incorporation of small-scale plasma effects.