F2, TEP (+/- Es link)
Note the similar distributions in these two tables - evidence, perhaps, that many of the October 1998 dx openings involved a sporadic E hop?
Comparison of 50 and 28 MHz dx, and Es with ionospheric data is instructive. In the graphs below, F2 daily maximum critical frequencies are plotted against dx daily area counts. On 28 MHz there is a good positive correlation: dx occurs on days with higher F2 MUFs. But there is no (or slightly negative) correlation at 50 MHz. F2 MUF does not appear to control days of 6m dx.
In the second set of graphs, dx area counts are plotted against sporadic E area counts. On 10m there is no significant correlation between F and Es openings - in fact the data suggests an absence of Es might be better for dx. On 6m there is a weak but positive correlation implying propagation to Europe [i.e. via Es] is the more critical factor enabling 50 MHz dx openings to the UK in October. This might help explain why it is often difficult to associate 6m dx openings with days of high solar flux or spot numbers.