12 Metres Sporadic E.

We're all familiar with sporadic E on VHF frequencies.  But how about 12m?  One never comes across any excitement about the 12m Es season opening or, indeed, any discussion about 12m Es at all.

Yet, it is pretty obvious to any regular user of 12m that the band is highly subject to Es propagation.

This morning, for example, 12m is again alive (during solar minimum) with short-skip signals from across the EU at very high, saturating signal strengths on JT65A.  The signals also show rapid changes in strength with time, indicative of gravity wave structures in the atmosphere.

Strong and rapidly fluctuating signals from central EU this morning.

To back up this idea, one only needs to look at one of the many MST radars placing their data online.  This morning, correlating well with the position of Es clouds as revealed by amateur radio signals, the 46.5MHz radar at Aberystwyth, mid-west Wales, shows strong returns from PMSE (ionised) structures which, at the signal strength reported, have probably just about reached visible ice structures as well (leading to NLC displays at night).

Here comes the PMSE...

So there is no doubt that Es is present and common at 12m.

The following day, a beautiful example of moving-surface drift was seen from EA5MM, underscoring the nature of Es propagation:

Curiously, the following day, 12m signals started appearing from central Europe in very strong form from nowhere.  This coincided precisely (at 19:00UT) with the passing of a cold front over my QTH and, within about six minutes, the band went dead again. The two signals, a HB9 and DL6 station, lay on a path perpendicular to the front's position.  Whether this was mere coincidence or not isn't clear to me, but it seems worth investigating!