Estimation of coronal magnetic fields using Type-I emission

The radial dependence of the coronal magnetic field above active solar regions is calculated using Type-I burst chain data existing in the literature. Assuming that Type-I emission is due to coronal shock waves, the upstream shock velocity and the density jump across the shock are obtained, respectively, from the drift rate and the bandwidth of the Type-I chains. Making use of the shock velocity and the density jump in the Rankine-Hugoniot relation, the Alfven velocity and hence the magnetic field in the corona is calculated. The results are compared with existing estimates. (author)