Re: LF: Daytime MF prpagation beyond the groundwave

[Markus Vester <markusvester@aol.com>]

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 <hvanesce@comcast.net>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
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-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Markus Vester
Sent: Sunday, December 4, 2016 7:09 AM
To: rsgb_lf_group@blacksheep.org
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 <f6cni@orange.fr>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
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 ).

 

73 Andy.

 

 

From: DK7FC

Sent: Sunday, December 4, 2016 11:52 AM

To: rsgb_lf_group@blacksheep.org

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