An Operational Approach to Forecasting Polar Cap Absorption (PCA) Events

摘要

One aspect of the Aerospace Environmental Support Center (AESC) support involves the effect of solar proton events upon transpolar high frequency (HF) radio propagation. This study addresses the problem of predicting the occurrence of Polar Cap Absorption (PCA) events resulting from solar proton enhancements near earth. Various aspects of the energetic solar flare event are reviewed and an attempt is made to assess their relative importance in arriving at a PCA forecast. Data pertinent to the flare event are considered in five general classes: radio burst data, X-ray burst data, optical data, solar region history, and the sector structure of the interplanetary magnetic field. An evaluation checklist is developed for use by the AESC forecaster. The checklist reflects the varying degrees of contributions of information in the five categories toward determining the 'Total PCA Factor.' (Author)