Improving Space Weather Forecasting Through the Observaion of the Coronal Magnetic Field

The Coronal Multichannel Polarimeter (CoMP) instrument, operated by HAO at the Mauna Loa Solar Observatory, is the only existing observational asset that obtains routine measurements of the coronal magnetic field. The CoMP instrument is moreover the prototype for the proposed Coronal Solar Magnetism Observatory (COSMO) large coronagraph. CoMP and, in the future, COSMO thus provide unique data for incorporating into space weather forecasting. I shall discuss the potential for CoMP and COSMO magnetic field measurements to improve observational models of the 3D magnetic field of the corona and to better forecast the expected magnetic configuration within CMEs, a property that is crucial for establishing their geoeffectiveness.