On the Prognosis of the OCCURRENCE` Date of GLEs

Up to May 2012 a total of 70 Ground Level Enhancements of Relativistic Solar Protons (GLEs) have been registered. Due to the complexity of the chain of involved processes, our present understanding of them is limited if we want to predict the occurrence of GLEs. However, to supply our deficiency with regard to the involved physics, we have developed special algorithms that allow for the prediction of the 1st GLEs of each group. We have grouped the 70 events in 6 well defined groups, on basis to the periodicity of 10.9 years, beginning with the first detected GLE on February 28, 1942. After reconstructing the date of the first event of each one of the past six groups, we determined the occurrence date of the first event of group seven, i.e., GLE71, which initiates in may 2012. In the middle of 2011, we have made a prediction of the GLE71 to occur during the end of 2011 up to the first months of 2012. Effectively, it had place on 17 May 2012. The method has been refined so that the 1st event of subsequent groups can be predicted within an error interval of ± 3 months. Prediction of subsequent events of a given group requires a modification of our technique, that is in the way of examination