  A comparison between observed (obs.) digital ionospheric sounding data and
predicted (pre.) using International Reference Ionosphere (IRI) model for
critical frequency (foF2) and Basic Maximum Usable Frequency (BMUF) of
ionospheric F2-Layer has been made. A mid-latitude region selected for this
research work by using data from station Wakkanai ($45.38^{o} N$, $141.66^{o}
E$). This study included 12 monthly median data from year (2001, $R_{12}=111$)
selected for high Sunspot number (SSN) and years for low SSN (2004,
$R_{12}=44$) and (2005, $R_{12}=29$). Frequency parameters foF2 reveals that
there is a good correlation between observed and predicted except for January
of years 2001 and 2004, and BMUF revealed that there is a good correlation
between observed and predicted for years of low SSN and all months except in
month 1, 9 and 12 of year 2004, for year 2001 of high SSN there is a bad
correlation. A correction factor as a function of time used from fitting
technique to correct the predicted value with observed value of BMUF for year
2001.

Space Physics