As in the past, storms in the central US impact everyone in North America, whether it be due to high QRN levels or low participation due to bad weather where stations are located. Coupling poor terrestrial weather conditions with a geomagnetic hangover and it results in a pretty slow session. The key is to remember that this is a marathon, not a sprint so participation will return to normal shortly and we will fight through whatever propagation and band conditions we are dealt. Welcome to Spring.
Most geomagnetic and solar metrics continue to be impacted although many of the values look better than 24-hours ago. Solar wind velocity has returned to low levels, below 400 km/s.
John, WA3ETD / WG2XKA, reports a weak session over all from Vermont.
While WSPR activity in North America was down during this session, 85 worldwide MF WSPR stations were observed on the WSPRnet activity page at 0200z. ZS1JEN was present once again from South Africa. David, G0MRF, reports that he sent him an email seeking details. Rik, ON7YD / OR7T, posted the following information on the RSGB-LF reflector:
some days ago I came across the website of Andre, ZS1JEN, and learned that 472-479 kHz is “released” in ZS.
Andre is very interested in 472 kHz (and 136 kHz) and did set up a (temporary) WSPR station and grabber (http://blogzs1jen.dyndns.org:83/472khz-grabber/)
So if anyone wants to try to leave a trace in ZS …
73, Rik ON7YD – OR7T”
Regional and continental WSPR breakdown’s follow:
There were no trans-Atlantic or trans-African reports during this session. UA0SNV was present but no reports were found in the WSPR database.
EA8/DL9XJ on the Canary Islands provided reports for DK7FC.
Eden, ZF1EJ, successfully reported many of the active stations on the noisy band during this session.
While high-latitude band conditions remain very poor, Laurence, KL7L / WE2XPQ, was somewhat successful at getting a signal out of Alaska, with reports from WH2XCR and WD2XSH/20. KL7L was designated as receive only.
In Hawaii, Merv, K9FD/KH6 / WH2XCR, decoded WE2XPQ, VK3ELV and VK4YB and was heard by VK4YB, KL7L and many on the mainland US. The JA path was closed off but I suspect weather is a factor as there were no late, participating JA stations during this session.
In Australia, Phil, VK3ELV, and Roger, VK4YB, received reports from WH2XCR while Phil received late Japanese reports from the previous session.
Jim, W5EST, presents a discussion entitled, “ROUNDTABLE: WH2XND & WG2XXM TA PROP INTO DL4RAJ, DJ0ABR, DH5RAE 3/7/16”:
“March 7 on 630m excites and mystifies: XND and XXM prop into Germany! At the same time of night, TA prop carried DK7FC both into New England’s WG2XKA and WE2XGR and further to WG2XJM and WA3TTS/2 in western Pennsylvania. Arizona’s XND even reached minus 8dB SNR at DL4RAJ 0502z! The March 7 RSGB-LF reflector and this blog same day carried the news.
Several North American 630m ops essentially round-tabled this TA event on ON4KST reflector later in the day, based on their experience. I summarize with their permission and give some commentary at the end of this post. Thanks to all!
Steve VE7SL: These 05z German spots decoding western USA stations are most encouraging. OR 630m can produce some exciting spotlight propagation that has gone unnoticed so far! I’ve read anecdotal reports of maritime ops copying CW signals from antipodes on their 500kc ‘watch.’
Laurence WE2XPQ: I used to hear UK coast stations on 500kc working whilst in “VP8” waters (far S. Atlantic to Antarctica) some evenings. Same time– often listen to Capital Radio 1548kHz London.
Both: Amateurs are going to shine a lot of light on new prop mechanisms…. yet much 630m to be learned by us ‘amateurs.’
Ron WH2XND: No Prop on 475 today whatsoever! Yesterday, daylight Prop!
Ken SWL/K9: No spot from XND today all day long on 630m… unlike 2200m frequent daytimes.
Ron WH2XND: Eric WG2XJM and I worked 475 LSB voice Saturday night (March 5) recorded there. S9 with XND 20w 630m ERP! 630m WSPR TA was also 20w ERP March 7, very strong TA capability with WSPR. Aurora has produced some really long distance contacts in the past.
Steve VE7SL: Geomagnetic disturbance! Certainly looks like some sort of ‘spotlight’ effect. I’ve seen similar spotlight openings to EU from here on a dead 6 meter band…no other signals around except a shifting spotlight between here and Europe, so maybe possible on 630m also…although I would not have expected to see a -8 level signal! Good CW copy level.
Laurence WE2XPQ: Positive compression duct on the equatorward side of the oval – or “auroral enhanced chordal hop” (given the levels!)
Steve VE7SL: Groundmaking event…hopefully repeatable. So much we don’t know about propagation. Throw in a geomagnetic storm, and all the ‘rules’ go out the window.
Jim W5EST: XXM March 7 2sp 5w XXM-dl4raj 8406km 30dB 0452z, -27dB 0502z. It resembles XXM Oct. 27, 2015 2sp 5w XXM-ea2hb 7765km -30dB 0216z, -28dB 0224z. Approximate symmetry 8 weeks before/11 weeks after winter solstice.
Jim W5EST: March 7 XND-dh5rae -16db 0502z 9352km. TX Power XND/XXM 20w/5w = 6dB maybe explains it, yet still great event into DH5RAE.
Jim W5EST: However, XND-dl4raj 0440-0512z peaked 0502z -8dB. TA prop pumped 19dB more XND than XXM same time into same DL4RAJ rx. XND/XXM 20w/5w = 6dB is not enough to explain this event! 630m mystery!
Keep in mind the roundtable was primarily propagation-interpretive rather than propagation-predictive, and that’s ok. Aurora is usually associated with high latitude 630m path absorption and low-SNR or none. So prediction of a high-SNR TA event based on aurora conditions would demand some further critical piece of information that we should seek to employ if there’s any hope of predictive capability someday for this type of event. The WSPR decoder cuts off around -30dB SNR which makes TA propagation seem somewhat rarer at longer distances than it probably really is in general.
Comparing 20w XND with 1w DK7FC puts the single-digit SNR of XND-dl4raj into a larger pattern. Whether the EIRP power measurement methods for DK7FC and XND are same or different, DK7FC power is probably at least 6dB to 13dB below XND power March 7. DK7FC seven nights this 2015-2016 season has delivered SNRs -16dB to -6dB into New England and -18dB SNR into ZF1EJ at 8393km (Data available on request). If you take that into account then one XND single digit -8dB SNR report at 9367km into DL4RAJ remains outstandingly remarkable but less incomprehensible.
This brings us to the question of propagation interpretation. Every 630m TA path this season has been a shorter path, and over saltwater to boot. DK7FC-zf1ej great circle was far south of the auroral oval. XND-dl4raj great circle path crossed southern Greenland within the red auroral oval on Ovation that night. So–isn’t the XND-dl4raj mechanism unique? Even if the longer TA paths this season share their propagation mechanism with the XND-dl4raj path, what is that mechanism?
3-F MULTIHOP: If multihop, hop distance considerations (E: 2800km, F: 4000km in Feb. 20 blog) would lead to a mixture of 4-Ehop and 3-Fhop for XND & XXM over their 9367km & 8406km paths. The map FIGURE shows the surface reflections for 4-Ehop and 3-Fhop. 4-Ehop has 3 surface reflections including a killer ground reflection in far western Ontario. XXM’s 3-Fhop has two surface reflection but one of them is likewise a killer ground reflection in Quebec. Only XND’s 3-Fhop offers just two surface reflections—both on saltwater–one in Hudson Bay and the other southwest of Iceland. 630m conditions could have allowed significant signal transmission through the E-layer to make strong F-layer reflections possible. The geometry of Hudson Bay would circumscribe the EU spotlight to 630m-active Germany and 630m less-active eastern Scandinavia and eastern Europe.
However, for both 4-Ehop and 3-Fhop, at least one ionospheric reflection would have occurred around southern Greenland and inside the auroral oval as far south as it was that night. The question arises if the auroral oval were absorptive as usual, instead of hypothetically and unusually reflective that night, what altitudes need to be bypassed to avoid the absorption? If the auroral oval introduces ionization at E or F altitude,* enhancing reflectivity instead, what surface reflections and absorption altitudes could be bypassed to deliver 19dB SNR advantage of XND over XXM?
DUCTING: Ducting could bypass at least one surface reflection, enhancing XND SNR. If ducting, where was the duct? Suppose a positive compression duct occurred due to aurora. Then I’d surmise entry into the duct on the equatorward side of the auroral oval at ionospheric altitude would have occurred on ascent over North Dakota. Then RF exited north of Scotland on descent into Europe. The exit geometry would then explain the spotlighting into SE Germany. XXM’s path, being farther to the south, would miss the beneficial compression duct geometry and encounter a lossy ground reflection thereby accounting for the 19dB of SNR difference. However, a duct would impose numerous internal reflections with their own losses due to its modest internal dimensions. And a G3 geomagnetic storm would have disconnected, disrupted or prevented any long duct geometry, wouldn’t it?
CHORDAL HOP: A chordal hop avoids at least one surface reflection by an ionospheric reflection horizontally (geometric chord of a circle) thanks to slightly tilted electron concentration contour surfaces. I think equatorward pressure exerted by aurora-producing particles would most likely tilt such surfaces to reflect lateral to the path rather than a way aiding the path. But the G3 geomagnetic storm might nevertheless have briefly produced the right tilt angles in the right geographic locations. Moreover, the special tilts could account for the XND reception solely enjoyed in SE Germany.
That said, if chordal hop prop occurred, the chordal reflections must have occurred at ionospheric altitude. Also–due to the curvature of the earth and its ionosphere–the maximum chordal distance of one chordal hop between its ionospheric reflection points is approximately the same as for one ordinary hop. Where then are the most likely reflective places?
I’d rule out E-layer chordal reflection because of many hops and the hop distance is too short to avoid the killer ground reflection in Canada. Yes, maybe, the auroral event could have produced one chordal reflection as far south as SE Wyoming** to bypass that ground reflection. But I doubt that alone would explain the XND -8dB SNR and 19 dB excess of XND over XXM. Yes, it’s remotely possible that two chords independently joined ionospheric reflection pairs 1-2 and 3-4, starting in SE Wyoming** or the North Sea*** to make an overall unique event. But I try to make explanations as simple as possible and that’s a stretch.
3-Fhop has only 3 ionospheric reflection points, and a chordal hop can join only two of them because of the tilting. If the chordal geometry is based on F-layer reflection assisted by the aurora event, one F-chord could have bypassed the northernmost ocean surface point SW of Iceland by traveling chordally overhead the N. Atlantic near Labrador to a point overhead Scotland*** before descending into Germany.
CONCLUSION: I personally think 3-Fhop near-great-circle multihop with Hudson Bay control of spotlighting is sufficient interpretation of XND-dl4raj on March 7. Duct prop requires one long special duct and introduces its own loss. Chordal hop prop presents even more difficulty because of the tilt directions needed and the geographic constraints imposed on this path by the chordal concept. I reject mere skew prop because it would not bypass a N. America ground reflection of XND on the way to Germany.
YOU TELL US: Based on the roundtable and this commentary, do you have further words of wisdom or suggestions to make? If so, please contact us at this blog. Thanks! “
*Per Even Sandholt, H.C. Carlson, A. Egeland, (2002) Dayside and Polar Cap Aurora. Kluwer Academic Publishers. pp. 33-36.
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD <at> gmail dot (com)!