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Re: LF: Daytime MF prpagation beyond the groundwave

To: [email protected]
Subject: Re: LF: Daytime MF prpagation beyond the groundwave
From: Markus Vester <[email protected]>
Date: Sun, 4 Dec 2016 14:17:48 -0500
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In-reply-to: <[email protected]>
Reply-to: [email protected]
Sender: [email protected]
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 ).

 

73 Andy.

 

 

From: DK7FC

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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