Forbush Decrease Prediction Based on Remote Solar Observations

Abstract

We employ remote observations of coronal mass ejections (CMEs) and the associated solar flares to forecast the CME-related Forbush decreases, i.e. short-term depressions in the galactic cosmic-ray flux. The relation between the Forbush effect at Earth and remote observations of CMEs and associated solar flares is studied via a statistical analysis. Relations between Forbush decrease magnitude and several CME/flare parameters were found: the initial CME speed, apparent width, source position, associated solar-flare class, and the effect of successive-CME occurrence. Based on the statistical analysis, remote solar observations are employed to forecast a Forbush-decrease. For this purpose, an empirical probabilistic model is constructed that uses selected remote solar observations of the CME and associated solar flare as input and gives the expected Forbush-decrease magnitude range as output. The forecast method is evaluated using several verification measures, indicating that as the forecast tends to be more specific, it is less reliable, which is its main drawback. However, the advantages of the method are that it provides an early prediction and that the input does not necessarily depend on using a spacecraft.