Evolutino of Coronal mm-Wave Sources

Coronal mm-wave emission at source heights up to the order 100 000 km above the photosphere are sporadically observed as off-limb sources by radio telescopes of medium angular resolution. Previous work showed that coronal mm-wave sources (CMMS) fall into different categories, e.g., explosive burst emission, post- and interflare radiation, and radiation from prominences. The source heights can be checked in the case of behind-limb sources. Systematic knowledge on the evolution of CMMS is still lacking. The present report discusses some general properties of CMMS and considers new observations from the Metsahovi Radio Research Station at 37 GHz of the year 1992 with respect to the effect of temporal evolution.