Coronal Dimmings in the Context of Space Weather Prediction

Coronal mass ejections (CMEs) often accompany coronal dimmings as isolated in coronal images in EUV wavelengths, although we empirically know that not all CMEs may be clearly registered with dimmings. Conversely, not all dimmings may inform eruptions successfully becoming CMEs. We attempt to evaluate the usefulness of coronal dimmings for predicting Earth-directed CMEs, based on a number of dimmings detected with different techniques. We characterize dimmings in terms of their magnitudes, thermal properties, 3D spatial distributions and evolution with respect to contemporaneous flares and coronal waves, using SDO/AIA and STEREO/EUVI images, SDO/EVE irradiance data and AWSoM numerical simulations. These characteristics of dimmings are compared with the properties of the associated CME if there is one. We discuss key dimming-related factors that can be more reliably used to predict Earth-directed CMEs and their geoeffective potential.