SOLRAD and many other satellite systems have provided a large data base showing the time-dependent behavior of broadband solar fluxes in the X-ray and EUV spectral regions. These bands are broad in the sense that one band may contain many ionospherically important spectral lines. We present results of tests performed to determine how this information can best be used to predict the effects of a solar flare on the ionosphere. Our approach has been to first adopt a model of the spectral line and continuum enhancements based on a synthesis of many types of flare observations. This detailed spectral model is used in a time-dependent ionosphere model to calculate the response of the electron and ion density profiles. Then the spectral model is mathematically filtered to show how it would appear to the SOLRAD EUV detectors, and this degraded information is used in the ionosphere model. Comparison of the two ionosphere calculations shows that the two spectra produce changes in the total electron content in the ionosphere that differ by only a few percent. Thus, given the present uncertainty in our knowledge of solar flare EUV spectra, SOLRAD broadband EUV solar flux measurements can be used to calculate the ionospheric effects of EUV flare enhancements. Significant changes due to the flare which occur in the individual species densities are described. |