Incoherent scatter spectrum in D region - Is there a discrepancy between observations and theory?

Esa Turunen and Thomas Ulich

Geophysical Observatory, FIN-99600 Sodankylä, Finland.

Most applications of incoherent scatter measurements in ionospheric D region are based on the assumption of a Lorentzian spectrum, the form of which is defined by several physical parameters. While this approach is widely used in published literature, some authors have shown clear discrepancies with observations and theory. We discuss these observations, as well as the related calculations based on conventional incoherent scatter theory. The possible reasons for the discrepancies are pointed out.