Forecasting geomagnetic activity three hours in advance for ionospheric applications

An attempt at forecasting the magnetic activity index three hours in advance is presented. This approach is based on a suitable treatment of time-weighted accumulations of the three-hourly magnetic index Kp. The statistical analysis of impact of magnetic activity on the positive and negative disturbances of the F-2 layer peak electron density NmF(2) is made for 25 ionosondes in Europe and Russia during 1997 to 2001. It is shown that the response of positive and negative ionosphere disturbances to peak of magnetic activity Kpmax delays by 1 to 48 h. Two peaks of occurrence of positive and negative ionospheric disturbed periods are found referring to Kpmax equal to equal to 4 and 5 for DNmF(2-) shifted regarding similar distribution of forecasted 3 and 4 for DNmF(2+), and Kpmax, Kpm indices depicting two maxima at Kp equal to 1.7 and 2.7. Comparisons are made with observations and IRI-2001 model predictions.