We explore a method to infer solar EUV fluxes, atmospheric composition and winds using ionospheric electron density Ne profile measurements. Incoherent scatter radar data from Millstone Hill and Shigaraki measured on October 5, 1989 are assimilated into a theoretical model whose driving forces, solar EUV flux, exosphere temperature Tex, and meridional winds are adjustable. Adjustments are made to give best match between the model $N_e$ profile and data. The derived Tex values, being low near noon at Millstone and high in the afternoon at Shigaraki, are essentially those required to give the [O]/[N2] ratio necessary to fit the data. Ourinferred EUV fluxes for the two sites are similar. While our technique of using profile data may resolve the ambiguity in deriving EUV and [O]/[N2], the accuracy of results depend on that of the data and model, and they need to be further confirmed.