Inversion of radiowave absorption data to establish ionospheric properties. I. Nondeviative absorption

Class ical approx imate predi ctions of t he a bsorp tion fun ction A(w) fo r several ionospheri c electron de nsity N and collision frequ ency v models deri ved from t hi s expression are fi rst reviewed . It is then shown t hat by solvin g t he above in tegral equation, one can establish a n explicit r elationship between Nand p at a ny height from a measured kn owledge of t he ab orp tion fun ction A(w) as a function of ca rr ier frequ ency w. Thu s, a knowledge of t he electron density profil e can be used to reco nstru ct t he collision frequency profi le a nd co nversely. It is shown t hat t he usual assump t ion A(w) = Aowz correspo nds to a n impossible ionospheri c model. Several exa mples a re given to ill ustrate t he a na lyt ical in version techni que a nd to in dicate its sensit ivity to low freq uen cy port ions of the measured a bso rption fun ction.