[SADXA] 40m Solar Noon DX Report for 2021

[W7EXG]

1/2/22

To: SADXA members

From: Bill W7EXG

RE: 40m Solar Noon [SN] DX Report for 2021 December Solstice

 

There have been many attempts by many SADXA members to either listen for SN
DX on 40m CW, and/or  run 40m SN RBN or WSPR Analysis from about 12/15/21 to
1/2/22. 

 

To Date, here have been NO reported 40m SN DX paths within +/- 1 hour of
Solar Noon.  Based on 40m WSPR analysis, it is unlikely any SN DX will occur
from now on. 

 

This is in sharp contrast to 2019 ( CW + many WSPR 40m SN DX verifications)
and 2020 (WSPR SN DX  verifications). 

 

Between 12/13 and 12/27 -- 2021, we saw the Sun spot numbers [SSN] sore from
30 to a peak of 140 with Solar Flux Index [SFI] increasing from 85 to over
140. Sun Spot number is currently 52 and Solar Flux is at 94. 

 

In contrast, in December 2019 the Sun spot Number was 0, and the SFI
averaged about 68. 

In December 2020, the Sun Spot Numbers were about 11, with Solar Flux at
about 84. 

 

In my 2019 40m DAY DX  presentations, I pointed out the significance of 40m
propagation during the Dec Solstice, and especially when having the lowest
Solar Indices at the same time [expected in December 2019]. In December
2019, W6XI and W7EXG set a milestone 40m DX record for the SADXA club, with
over 10 EU SN DX CW contacts, some within minutes of the Tucson  Solar
Meridian. 

 

The best 40m DAY DX occurs with the lowest Solar Indices because of the
absolute minimal D absorption (Less loss per hop) and the lowest EMUF to
optimize  F2 layer propagation. 

 

The best 40m SN DX occurs during Dec Solstice, because the Northern Solar
Terminator is only 1100 miles from the US border at US solar noon. This
allows fewest hops for US Solar Noon signals to get to the DARK Terminator
for northerly paths. 

 

I believe 2021 with the higher solar indices has now reached the upper solar
indices threshold, thereby  prohibiting 40m SN DX. 

 

Unless we see lower solar indices during this or future Dec Solstice, we may
need to wait until about 2030 for the NEXT 40m SN DX opportunity to occur
again. 

 

I want to thank all SADXA members who gave a listen on 40m at SN in 2021,
either on CW, RBN, FT8 or WSPR. 

 

I especially want the thank SADXA  member Darrel Emerson AA7FV who ran
countless WSPR 200W transmissions under various Solar Indices during this
and past years mentioned. This WSPR data clearly quantified the 40m SN DX
paths as a function time, day, and a function of the Solar Indices from year
to Year during the respective December Solstices. This data proved to have
immense value to the overall understanding of 40m SN DX. 

 

Best 73's to all and Happy New Year

Bill W7EXG