Model of topside ionosphere scale height based on topside sounder data

A new model of topside ionosphere scale height is developed, based on the vertical electron density (Ne) profiles obtained from topside ionosondes. The model provides the vertical scale height (VSH) as a function of month of the year, local time, geomagnetic latitude, solar flux F107 and Kp index. To define VSH, the O+ scale height above the peak of the F2 layer is assumed to be represented by the lowest gradient in the measured profile. The model data base contains 170,033 VSH values, extracted from individual N(h) profiles gathered between 1962 and 1978 by Aluoette and ISIS satellites. The data sample sufficiently all parameter’s ranges. The model describes the vertical plasma scale height by a multivariable polynomial consisted from Tchebishev’s and trigonometric base-functions, which are fitted to the data in the 5-dimensional space. The overall model error is 34.6 km, or 23%. The model VSH variations along the different parameters are presented. The model results are compared with those extracted from IRI.