Empirical modeling of the upper transition height for low and middle latitudes Original Research Article

Ion composition data measured by the Bennett mass spectrometer during the ACTIVE mission (perigee 500 km, apogee 2500 km, maximum of the solar cycle 22) and from AE satellites from the minimum of solar cycle 21 was used to study the solar activity influence on the global behaviour of the upper transition height. In a first approximation the invariant latitude and magnetic local time dependence is considered and described by spherical harmonics up to the 6th order. Submodels for equinox and solstices for high and low solar activity are presented.