The great WSPR experiment ends.

Well, it doesn't matter how interested one is in WSPR, it's a big ask to get any station to surrender normal operations and keep transmitting signals over several days.

But, with a fine example of cooperation between Argentina and Wales, we have obtained very valuable data on solar minimum, mid-winter night propagation between hemispheres.  Valuable, because with every passing day, the solar cycle is slowly changing, and we will have to wait for many years before the next solar minimum.

Valuable also, because whilst there are a large number of amateur radio operators in Latin America, only a very small number - typically just one or two - operate WSPR on a fairly regular basis.

So, for the last time this winter, some very interesting results that at least confirm that a changing geomagnetic field modifies 14MHz propagation at this time quite dramatically.

First, the field, which showed moderate, high-latitude disturbance (Kp ~2) of the kind that we can expect on a more-or-less daily basis, but a little more energetic than fully quiet conditions:

Image: Tromso Geophysical Laboratory.

Next, my spots of LU8DPV:

This is an unusual pattern on two counts: (1) the usual smooth curve in signal strength before midnight is modified into a suppression of signals as the high latitude Z component becomes disturbed and (2) the peak in signal that does occur is later than usual, compressed into a sharp spike, and reaches a very strong +5dB SNR/2500Hz just before UT midnight.

Clearly, the disturbance is limited to very high latitudes, coincident with the auroral oval.  But some effect is being felt much further afield than this to allow LU8DPV to be heard here.

Also unusual overnight was the persistent detection of HZ1SK, who seems to enjoy some kind of 'favoured link' with Wales, as there are no other stations in that region - or anywhere near it - that come through at these dark hours:

Here, HZ1SK shows a decline in signal as the terminator recedes, with no signal from around 21:00UT to 00:30UT, when the high latitude disturbance is underway, and then a strong return as the field restores to quieter conditions.

The other few signals that kept coming overnight were G0CCL, IT9CJC, and, to a lesser degree and with much higher power (20W), PA3BTI.

First, G0CCL:

Again, something of a suppression in signals as the high-latitude disturbance was underway, followed by a definite peak in signal strength just after midnight, again as the field restored.

Next, IT9CJC, which follows much the same pattern, with a slight timing difference:

And finally, PA3BTI, which merely confirms the finding that a moderate disturbance at very high latitudes can have quite a strong effect on propagation, bringing signals that, under quieter conditions, would not be detected at all up to not only detectable but quite strong levels: