On the day-to-day variation of the MUF over Europe

Limits of day-to-day variability of MUF as a function of level of solar act ivity, time of day and geographic latitude are given in the ITU-R recommend ations. However, these reference values are derived from the analysis of da ta collected in the American zone three decades ago. In this work an invest igation of the hourly daily values of MUF collected in the European area is attained and new bounds of MUF variability are derived. Examples of observ ed daily measurement data not used in the analysis and predicted ones are r eported. The comparison shows that the proposed reference figures are accep table on the whole. (C) 2000 Elsevier Science Ltd. All rights reserved.