A new vary-chap model of topside electron density profiles based on ISIS-2 sounding data

Using ISIS-2 topside sounding data, a new representative model of the topside electron density distribution is being developed for use in IRI. A major challenge for topside N(h) modeling is finding a suitable mathematical representation of the topside vertical profiles. Many representations have been proposed including exponential functions, Epstein functions, sech-squared functions, and Chapman functions with one or two fixed scale heights.