Back-scattering of MF electromagnetic energy from the Antarctic stratosphere

Abstract

A short review of the partial reflection experiment is presented along with the commonly made assumptions regarding the scattering mechanisms of the MF magneto-ionic modes in the mesosphere. It is shown that the traditional method of analysing differential absorption data can give rise to considerable errors in the determination of ionisation density at a particular scattering height. A new analysis approach is presented which yields a profile of the product of electron density and collisional frequency, rather than estimates of the electron density only. A by-product of this analysis technique is an estimate of the reflection coefficient factor F xo ( h) which traditionally has been set identically equal to unity. Analysis of data collected from 1983 to 1998 at Scott Base, Antarctica, has revealed that this reflection coefficient factor exhibits a seasonal dependence and differs substantially from unity, particularly at scattering heights between 40km and 60km. It is shown that neglecting this factor could easily lead to the conclusion that differential absorption is present at certain scattering heights with the consequent implication of the presence of ionisation.