Preliminary results on the within-the-hour ionospheric variability

Studying the variations of the within-the-hour relative deviations of daily 5-minutes measurements of the critical frequencies f(o)F2, f(o)E and the p ropagation factor M(3000)F2, it is shown that the deviations of these param eters follow a different statistical distribution in different percentages of the time in each month. Latitudinal dependences of the within-the-hour v ariability are investigated. Finally comparisons between distributions lead to preliminary quantitative specifications of the within-the-hour variabil ity for each of the examined ionospheric parameters. (C) 2001 Elsevier Scie nce Ltd. All rights reserved.