Comparison of regular(diurnal,seasonal and solar cycle)variations of high-latitude,mid-latitude and low-latitude ionospheric characteristics has been provided on basis of local empirical models of the peak electron density and the peak height.The local empirical models were derived from the hand-scaled ionogram data recorded by DPS-4 digisondes located at Norilsk(69°N,88°E),Irkutsk(52°N,104°E)and Hainan(19°N,109°E)for a 6-year period from December,2002 to December,2008.The technique used to build the local empirical model is described.The primary focus is diurnal-seasonal behavior under low solar activity and its change with increasing solar activity.Both common and specific features of the high-latitude(Norilsk),mid-latitude(Irkutsk)and low-latitude(Hainan)regular variations were revealed using their local empirical models. Comparison of regular (diurnal, seasonal and solar cycle) variations of high-latitude, mid-latitude and low-latitude ionospheric characteristics has been provided on basis of local empirical models of the peak electron density and the peak height. Local local models were derived from the hand-scaled ionogram data recorded by DPS-4 digisondes located at Norilsk (69 ° N, 88 ° E), Irkutsk (52 ° N, 104 ° E) and Hainan 6-year period from December, 2002 to December, 2008. The technique used to build the local empirical model is described. The primary focus is diurnal-seasonal behavior under low solar activity and its change with increasing solar activity. of the high-latitude (Norilsk), mid-latitude (Irkutsk) and low-latitude (Hainan) regular variations were revealed using their local derived models.