Determination of Chapman and Vary-Chap variable scale-height profiles by inversion of vertical electron density profiles

Abstract

There is a class of generalized Chapman functions which depend on a variable, height-dependent scale-height function. This class of functions has applications in electron density models of the ionosphere, plasmasphere, or of the combined ionosphere plasmasphere system, e.g. in the IRI model which is currently being extended to the plasmasphere using so-called Vary-Chap functions. We propose a set of analytical methods by which a variable scale-height function can be computed from a given vertical electron density profile, and discuss the application of this method to electron density profiles reconstructed from GPS data collected onboard of the CHAMP, GRACE, and COSMIC/Formosat-3 satellites. We also discuss the limits of the proposed method with respect to numerical stability and sensitivity to noise in the input data.