Using the IRI model to determine parameters of HF propagation 

Olga Maltseva and Oleg Poltavsky 
Institute of Physics Southern Federal University, Rostov-on-Don, Russia 

Despite a very intensive development the IRI model is practically not used for 
tasks of HF propagation. It might be connected with a fact that the modification 
of the IRI model are hardly concerned parameters needed for HF propagation, in 
particular, M3000. For the last time this parameter became the subject of more 
close attention. Certain expectations are connecting with new version IRI2007 
that is supposed to include a new version of M3000 model. The purpose of this 
paper is to investigate efficiency of using model parameter M3000. The simplest 
method of such an investigation is to use experimental values of the maximum 
usable frequency (MUF) and model values of M3000 to determine foF2 in the middle 
of the path and to compare these values with data of vertical sounding. For this 
purpose the following experimental data are used: 1) medians of M3000 and MUF 
for different Australian stations (McNamara et al., 2007) allowed comparing  
some approaches (ASAPS, GAIM, IRI), 2) medians and concrete values of M3000 
for 7 stations in the world (Oyeyemi et al.,2007) allowed comparing models 
IRI2001 and IRI2007, 3) values of MUF for the two European paths Rome-Linkoping 
and Chelveston-Linkoping (Broms and Zolesi, 1995) allowed comparing  results of
the IRI model and linear regression of experimental data. Preliminary results for 
these points are as follows. 
1. The IRI model provides a correspondence between experimental and model values of 
M3000 better than the GAIM model by factor of two (relative RMSE were 4.36 and 
8.26%). Estimates for foF2 gave 9.36% for IRI and 8.44% for GAIM. Relative RMSEs 
of MUF were 11.9% for GAIM, 9.2% for IRI and 8.4% for ASAPS. 2. Using 
M3000(IRI2001) and M3000(IRI2007) for 16 cases showed the following estimates of 
absolute deviations, RMSEs and relative RMSEs: 0.96 and 1.16MHz, ~18%; 0.35 and 
0.45MHz, 7.94%; 0.3 and 0.4MHz, 6.74%. 3. Comparison of experimental MUF values 
with ones calculated by a) the IRI model, b) experimental coefficient of linear 
regression, c) experimental MUF value of the other path using M3000(IRI) gave 
estimates: 2.8 and 3.38MHz, 27.7%; 1.16 and 1.5MHz, 12.1%; 1.0 and 1.29MHz, 10.1%.