Stefan, Roleof and Markus, Thank you for all of the winter propagation information, it is most interesting and very much appreciated. Roleof, could you mention the station that you heard from Churchill? We visited Churchill a few years ago and would really enjoy hearing a station from there. 73, Jim AA5BW From: [email protected] [mailto:[email protected]] On Behalf Of Markus Vester
Sent: Sunday, December 4, 2016 2:18 PM
To: [email protected]
Subject: Re: LF: Daytime MF prpagation beyond the groundwave Hi Jim,
I have to admit that I have no proof that the "winter anomaly" has any effect on the lower ionosphere. As Roelof and others have indicated, increased daytime MF / LF signal strength may rather be due to less (and not more) buildup of absorbing D-layer ionisation during shorter daylight hours. In addition, QRN activity tends to be lower at least in mid latitudes.
Best 73,
Markus (DF6NM)
-----Ursprüngliche Mitteilung-----
Von: hvanesce <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: So, 4 Dez 2016 4:15 pm
Betreff: RE: LF: Daytime MF prpagation beyond the groundwave Markus and Stefan, Thank you for the winter anomaly reference and example. Stefan originally referred to 630m and Markus’ comments did not specifically ascribe the anomaly itself (just groundwave distance) to VLF but I am curious: is the anomaly evident at VLF? Reliable at VLF? My question relates to the wiki description of an F2 layer effect, and I wondered if F2 (and hence the anomaly) is perhaps significant in nighttime VLF propagation, or if perhaps there is also some process similar to the F2 winter anomaly in the D layer which would affect VLF. Do either of you have thoughts on the winter anomaly at VLF frequencies? 73, Jim AA5BW From: owner-[email protected] [mailto:[email protected]] On Behalf Of Markus Vester
Sent: Sunday, December 4, 2016 7:09 AM
To: [email protected]
Subject: Re: LF: Daytime MF prpagation beyond the groundwave Hi Andy, Stefan,
daytime propagation on VLF/LF beyond a few100 km (and likely also on MF) is dominated by ionospheric reflections, rather than groundwave. Despite lower solar elevation on winter days, the ionisation is actually stronger than in summer. This effect is known as the "winter anomaly": https://en.wikipedia.org/wiki/Ionosphere .
Best 73,
Markus (DF6NM)
-----Ursprüngliche Mitteilung-----
Von: F6CNI - Andy - JN19QB <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: So, 4 Dez 2016 12:30 pm
Betreff: Re: LF: Daytime MF prpagation beyond the groundwave Hello Stefan. Sorry but I do not understand. Can you explain to us scientifically why you said that there is a difference enter winter and summer for day time groundwave mode of propagation ? Also, an other question : can you tell us honestly which is your exact EIRP transmitting power, because on day time groundwave there is not usual to have a WSPR2 report on the 630 meters band of –17 dB S/N over 1500 km (Remember that he legal maximum power in DK is 1 Watt EIRP, and nobody can ignore the law ). Sent: Sunday, December 4, 2016 11:52 AM Subject: LF: Daytime MF prpagation beyond the groundwave Hi MF,
I just sent a single WSPR block and got the following results from distances above 300km.
This is typical for the winter season.
73, Stefan 27 spots: Timestamp | Call | MHz | SNR | Drift | Grid | Pwr | Reporter | RGrid | km | az | 2016-12-04 10:46 | DK7FC | 0.475682 | -20 | 0 | JN49ik | 1 | LA2XPA | JP33wi | 1548 | 358 | 2016-12-04 10:46 | DK7FC | 0.475685 | -17 | 0 | JN49ik | 1 | OH1TSM | KP11db | 1546 | 28 | 2016-12-04 10:46 | DK7FC | 0.475682 | -6 | 0 | JN49ik | 1 | LA8AV | JO59cs | 1153 | 4 | 2016-12-04 10:46 | DK7FC | 0.475682 | -12 | 0 | JN49ik | 1 | LA6LU | JO59eq | 1145 | 5 | 2016-12-04 10:46 | DK7FC | 0.475682 | +2 | 0 | JN49ik | 1 | LA3EQ | JO28xj | 1012 | 351 | 2016-12-04 10:46 | DK7FC | 0.475682 | -19 | 0 | JN49ik | 1 | G3XKR | IO70ux | 940 | 285 | 2016-12-04 10:46 | DK7FC | 0.475682 | -19 | 0 | JN49ik | 1 | SP5XSB | KO02ld | 911 | 66 | 2016-12-04 10:46 | DK7FC | 0.475683 | -6 | 0 | JN49ik | 1 | G8HUH | IO81mg | 851 | 288 | 2016-12-04 10:46 | DK7FC | 0.475674 | -19 | 0 | JN49ik | 1 | M0FMT | IO91ux | 693 | 297 | 2016-12-04 10:46 | DK7FC | 0.475622 | -12 | 0 | JN49ik | 1 | G0VQH | JO02fe | 655 | 301 | 2016-12-04 10:46 | DK7FC | 0.475682 | -23 | 0 | JN49ik | 1 | IW4DXW | JN64bw | 563 | 151 | 2016-12-04 10:46 | DK7FC | 0.475684 | +1 | 0 | JN49ik | 1 | PA0RDT | JO11tm | 428 | 305 | 2016-12-04 10:46 | DK7FC | 0.475686 | -8 | 0 | JN49ik | 1 | PA7EY | JO22jj | 428 | 322 | 2016-12-04 10:46 | DK7FC | 0.475682 | -4 | 0 | JN49ik | 1 | PE1RKT | JO22fb | 418 | 316 | 2016-12-04 10:46 | DK7FC | 0.475684 | -15 | 0 | JN49ik | 1 | PA3ANG | JO32am | 390 | 332 | 2016-12-04 10:46 | DK7FC | 0.475686 | -12 | 0 | JN49ik | 1 | DL-SWL | JO52hp | 381 | 20 | 2016-12-04 10:46 | DK7FC | 0.475681 | +12 | 0 | JN49ik | 1 | DH5RAE | JN68qv | 345 | 98 | 2016-12-04 10:46 | DK7FC | 0.475682 | +1 | 0 | JN49ik | 1 | PI4THT | JO32kf | 336 | 338 | 2016-12-04 10:46 | DK7FC | 0.475682 | -12 | 0 | JN49ik | 1 | PA0MLC | JO31aw | 335 | 327 | 2016-12-04 10:46 | DK7FC | 0.475682 | +7 | 0 | JN49ik | 1 | DJ0ABR | JN68nt | 329 | 101 |
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