Improved HF propagation and system performance predictions under ionospherically extreme conditions

The rapid increase of solar activity which occurred during the October-November 2003 period caused a series of unexpected phenomena in ionospheric radio-propagation conditions. These indicate deficiencies in the standard electron concentration models adopted for radio-conditions prediction and forecast and for system-performance assessments. This paper presents post factum analyses of the conditions during 3 days of maximum of this increase of space weather activity - 29-31 October 2003. Their modeling by means of the IRI as well as via the use of other models is discussed. The desired approach is specified for future applications in radio-conditions modeling for radio-systems evaluation.