DX cut-off 19:30 (KE7A) -26dB in agreement with ionospheric sunset.
Anomalous spots.
21:30UT PY1EGB -25dB Heard only by one other on dark side, V51PJ 22:40, 50UT @-26dB
22:36UT VE7PGB -18dB Heard only by one other dark side, V51PJ 22:16 @ -28dB
23:02UT W7YLQ -22dB
23:24 (-21dB), 23:30 (-23db), 23:48 (-13dB) K6MCS Appears inactive after ca. 00:30UT.
K6MCS also heard, all at ca. -22dB by:
PI4THT, V51PJ, PA0SLJ/3, ZS6KW, G0LUJ all 23:00-23:48UT
00:38, 40, 42, 44, 52, 54, 58UT N0NHJ
02:28-02:52UT N0NHJ. (same break/restore pattern for G0LUJ). All N0NHJ spots at -24 to -28dB.
Geomagnetic activity.
N0NHJ provides perhaps the most interesting indicators for this run. The geomagnetic field in the 00:38 to 00:58UT spots window is shown to be initially quiet and then to undergo a minor but significant increase in activity that appears to coincide with the spots. Between 01:00 and 02:26UT, when the spots vanish, the field is shown to be quiet. For the second N0NHJ spots window, the field undergoes rapid pulsations between quiet and moderate activity.
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| 00:45UT peak of ongoing field enhancement. |
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| 01:10UT collapse from higher activity. |
For the other western US stations heard, the field was essentially quiet at the time of the spots, ahead of a significant increase in field activity from about 00:00UT onwards (when only N0NHJ was heard).
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| Field at 23:20UT, broadly middle of spots window for s western US stations heard (not N0NHJ) |
The Kiruna magnetogram clearly shows a minor disturbance around the midnight period, which is in agreement with the anomalous spots heard (other than the later N0NHJ, which occurs during a smaller dip during field restoration):
Perhaps it is changes in the field, rather than the absolute strength of the field, that is important in bringing about these anomalous spots? The more interesting question for now is why only a few far western US station spots, and why are they only heard by the tiny number of dark side stations when there are so many out there to potentially hear the same thing? Does the inclusion of near-tropical latitude African stations hint that, rather than a polar-only phenomenon, it is in fact more a geomagnetic teleconnection-type phenomenon, between poles?
Comment.
That fact that V51PJ heard a couple of the far-west US stations is very interesting from the viewpoint that V51 is only about 28 degrees south of the equator, which is very far from either pole. It is just past midsummer, with the sun overhead at V51 at the moment. ZS6 is much the same latitude (22 degrees S). As is the situation (22 degrees S) at PY1EGB, heard at 21:30UT. Is that a clue? The lack of many WSPR stations in Latin America and Africa makes figuring this out very difficult.
Update (11/01/2018).
I've done some reading of highly-technical and specialised papers on the geomagnetic field and propagation studies.
From this, one interesting phenomenon is highlighted which may explain the very latitude-similar V51, ZS and PY spots - the Appleton Anomaly, or Equatorial Plasma Fountain.
1 comment:
This is going to be more interesting everytime I read about it at your blog. Have we discovered something new? Like PMSE and SSSP on 6m in summer? Is this something that only happens in wintertime? Let's say a Winter Solstice Short Path? But at the other hand the V51PJ spots make that unlikely except if his spots are a coincidence long path spots? I don't think the exceptional QTH from you and LUJ can be considered as the SDR at Twente university uses a "mini whip" on the roof of the building (http://websdr.ewi.utwente.nl:8901/qrt.html). However it is receiving very well despite it is not a RFI free surrounding. I think it is time to switch on my WSPR receive again! 2 researcher find more then one! 73, Bas
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