This session had a promising start in the early evening with openings from Texas into the Midwest where noise was already beginning to ramp up in the early evening due to storms in that area. The forecast here changed, meaning storms were expected over night and the decision was made to QRT at bedtime due to the rate at which the cold front was advancing. Unfortunately it was all for nothing because the storms did not arrive until 1100z. Its difficult to forecast the weather for the weather service.
Geomagnetic conditions continue at quiet levels but are more elevated than the previous session. Solar wind velocities are low, below 400 km/s and the Bz is pointing slightly to the South. Protons were elevated during the session. DST values have been variable.
John, WA3ETD / WG2XKA, reports a lean band overnight although transcontinental reports were present. John offers the following comments:
Neil, W0YSE/7 / WG2XSV, reports that his session continues to focus on stations in the West and provides these details:
Vinny, DL0IL, reported on the RSGB LF reflector that he has built a small vertical at the DL0IL/p field day site and will be operating MF WSPR, CW and JT9 through the weekend. Vinny reports that he would be QRV on 472.5 kHz at sunset around 1900z. Wolf, DF2PY, made an inquiry about the time and frequency so hopefully a QSO will result.
Regional and continental WSPR breakdowns follow:
There were no WSPR reports from the trans-African or trans-Atlantic paths during this session. UA0SNV and ZF1EJ were present but no WSPR reports were found in the WSPRnet database.
Laurence, KL7L / WE2XPQ, reported WH2XGP and WH2XCR during this session:
Merv, K9FD/KH6 / WH2XCR, received reports from the western US, Alaska, and Australia and provided reports from WG2XSV, WH2XGP, and VK4YB. Roger, VK4YB, reports subdued activity in Australia but a consistent path with Hawaii in the mid -20 dB S/N.
Jim, W5EST, continues his recent train of thought with “PART III: 630M LONG PATH PROPAGATION: HOW?”:
“Yesterday’s graph illustration showed WSPR SNR curves vs. distance. Propagation by one or more E-hops appeared to be the norm in temperate latitudes. By contrast, F-multihop propagation more nearly approximated the reported N.Am.-VK and HI-VK peak SNRs.
How could one reconcile all-E reflections at temperate latitudes with all-F reflections on the way to Australia? Both SE Australia and western N.Am. lie in temperate latitudes (positions per appended TABLE).
Possibly one F-hop contributes partially to the HI-VK and N.Am.-VK paths. See today’s illustration. Then the remainder of the distance would be mediated by the usual E-hop propagation in the temperate latitudes at either end of a N.Am.-VK path. Hawaii is farther south where an F-hop might or might not emanate directly from XCR. In general, this mixed-multihop modality would move one or maybe even two F-hop curves up and left on yesterday’s graph illustration to join with the curve for an applicable number of E-hops.
An included F-hop makes for a somewhat higher launch angle. This way, path SNR benefits from the steeply inclined dB vs. Angle elevation pattern of a vertical TX antenna.
To satisfy the path geometry, such consecutive E and F-hops would require:
1) Launch angle for E-hop equal to the reflection angle for F-hop.
2) All the hop distances total up to the TX-RX path distance.
3) A region of reduced E-layer reflection admits RF to the F-layer to do an F-hop.
4) The region of reduced E-layer reflection exists during nighttime in its locality.
5) To support one F-hop, the region width along the path is at least as wide at 150km altitude as an E-hop length elsewhere. (See top-center dashed arrows for non-occurring E-hops in VK-JA.) To support two F-hops, the region width along the path would have to be at least as wide at 150km altitude as three such E-hop lengths.
6) The region width that could admit F-hop(s) along the path has to be actually positioned geographically where the geometry of the path permits some F-hop to exist.
A spreadsheet according to all these requirements is doable, but challenging. Before embarking on a spreadsheet project, let’s ask whether there’s any geophysical support for any region making way to the F-region. So I did some looking. The equatorial region indeed might accommodate F-hop propagation:
“Within approximately ± 20 degrees of the magnetic equator, is the equatorial anomaly. It is the occurrence of a trough in the ionization in the F2 layer at the equator and crests at about 17 degrees in magnetic latitude. The Earth’s magnetic field lines are horizontal at the magnetic equator. Solar heating and tidal oscillations in the lower ionosphere move plasma up and across the magnetic field lines. This sets up a sheet of electric current in the E region which, with the horizontal magnetic field, forces ionization up into the F layer, concentrating at ± 20 degrees from the magnetic equator. This phenomenon is known as the equatorial fountain.”
https://en.wikipedia.org/wiki/Ionosphere (4.2 Equatorial anomaly)
The magnetic equator runs E/W within about 2° of the geographic equator on the Pacific Ocean paths that go near Hawaii. The magnetic equator runs about 8° north of the geo-equator where the VK-JA path crosses it. Scroll 1/3 on the link and click to obtain a 2014 world magnetic map:
Figure 1 in a paper by Risbeth in 2000 (see endnote*) shows high nighttime F-region electron concentration around the magnetic equator. This Risbeth paper surveys some of the scientific literature on the equatorial F-layer.
N.Am.-VK paths run 45°-55° NNW of magnetic equator to E/SE Australia and thus make a considerable angle from north. Angling across the equatorial region that way would support one F-hop to assist SNR and possibly even make way for two F-hops. If the equatorial anomaly spans a full +/-20°, that’s 4450km of north-south width (=6371km Earth radius x 40°/57.3°). Angling across it at 45° gives a 6300km available extent (4450km/sin45°). That may be a little tight to encompass 3 widths of E-hop and also be positioned geographically just right to make 2 F-hops possible, but I can’t be sure.
By contrast, the Japan path VK-JA may admit one F-hop but is probably too narrow for two F-hops because VK-JA path runs almost directly north–about 5-10° NNW of the magnetic equator. One lossy ground reflection inland from Cairns in far northern Queensland may also mix into the picture to yield the VK-JA SNRs plotted yesterday.
Perhaps it’s a stretch to think that 630m SNR information we gather from thousands of miles away might invoke the equatorial anomaly. Let’s look forward to learning more. Is this type propagation well-known already to 160m folks?** If you have information related to the topic, please let us know!”
* Risbeth, H. (2000). The equatorial F-layer: progress and puzzles.
Ann. Geophysicae 18, 730-739.
**Oler, C., & Cohen, T.J. N4XX (1998). The 160-Meter Band: An Enigma Shrouded in Mystery. CQ Magazine, March-April, 1998, at:
TABLE: GEOGRAPHIC POSITIONS OF SELECTED 630m STATIONS
STATION LOCATION LAT./LONG. (est.)
VE7SL British Columbia 48.8°N./123°W
WH2XGP Washington 45.5°N./120°W
JA RXs Honshu 35.7°N./220°W (140°E)
WH2XXP Arizona 33.4°N./112°W
WG2XXM Oklahoma 35.0°N./ 97°W
WH2XCR Molokai 21.1°N/ 157°W
VK4YB Queensland 27.5°S./ 207°W (153°E)
VK2DDI New South Wales 34°S. / 209°W (151°E)
VK2XGJ New South Wales 34°S. / 209°W (151°E)
VK3ELV New South Wales 34°S. / 212°W (148°E)
Additions, corrections, clarifications, etc? Send me a message on the Contact page or directly to KB5NJD <at> gmail dot (com)!