Calculations of ionization drift velocity by the Titheridge method from results obtained at the Irkutsk digisonde

The feasibility of the Titheridge method [1] to estimate vertical ionization drift velocity V is discussed. The initial data are values of the maximum F2-layer height (hm F2) derived from measurements with the digital ionosonde DPS-4 in Irkutsk (Institute of Solar-Terrestrial Physics SB RAS) over the 2003 to 2006 period. Neutral gas parameters are computed from the thermosphere model [2]. The obtained calculations of ionization vertical drift velocity are estimated by comparing with the empirical model [3]. In some cases, we reached a good agreement with the said model. However, this agreement is not constant, and the reason for these differences is still unknown. Diurnal variations of ionization vertical drift velocity in different seasons are also discussed