Replacement of the present sub-peak plasma density profile by a unique expression

Abstract It is proposed to apply Booker's ‘skeleton’ description which is actually used in IRI fu¨r the topside only, in future for the bottomside too. However, in order to overcome some drawbacks a slightly more involved descriptive function must be applied the time- and place-dependent parameters of which may be determined once for ever by fitting methods (as was earlier done for the topside). In order to avoid interference between different height ranges, in particular between the ranges lower, middle and topside ionosphere, it is proposed to use independent descriptions in these ranges and connect them smoothly by suitable ‘filter functions’. So, finally, a unique analytical expression covering all heights might be obtained.