On the Estimation of the Electron Collision Frequency in the F-region

Abstract

The electron collision frequency variations in the E and F regions have been determined by many workers in the past and currently at the Delhi University using the well known Appleton formulae which relates absorption, group-height and phase-height. The validity of this formula has been examined in this paper. A number of model electron density distributions and an assumed constant collision frequency value of 3^.5 x 10³ sec^-1 for the entire region have been used to calculate the variations of absorption, group and phase heights for different geomagnetic parameters including the phase integral corrections. Using these data the mean value of ν is recovered with the help of the Appleton formulae. It is found that for the a-mode the recovered value of ν, assuming the collision frequency to be constant in the height range concerned, agrees with the assumed value within 5% for all stations with dip angles ranging from 0 to 90 deg.