USE OF SIMULTANEOUS EUV AND SOFT-X-RAY MEASUREMENTS FOR DIAGNOSTICS OF THE SOLAR-FLARE RADIATION DANGER

The fluxes of extreme ultraviolet (EUV) and soft X-ray emission are ke y parameters for modelling the ionosphere and upper atmosphere. A new aspect is considered in using these fluxes for diagnostics and short-t erm prediction of proton radiation danger from the flare. The EUV (lam bda < 105 nm) and soft X-ray (0.1-0.8 nm) fluxes were compared for two types of solar flares. The first type is followed by a strong enhance ment in solar energetic (E > 10 MeV) proton flux, the second is not fo llowed by any enhancement in proton flux. It was discovered that the f lare UV flux was considerably higher for flares with plutons than for those without protons. Soft X-ray fluxes were approximately equal in b oth cases. An excess of EUV emission in proton flares grows with incre asing proton Box. An analytic expression was found for the growth in p roton flux as a function of the excess of EUV radiation at a given X-r ay flux. These results can be used in predicting flare radiation dange r.