[SADXA] 40m Solar Noon DX during 2021 Dec Solstice - The Challenge

[W7EXG]

TO: SADXA Members (12-14-21)

From: Bill W7EXG

RE: 40m Solar Noon DX -  Dec. Solstice Period 2021 (NOW)

40m DAYTIME DX

You are likely hearing 40m DAYTIME DX well before SS and well after SR
during this Dec Solstice Period. 

 

40m Solar Noon DX - Overview

Some SADXA members may recall my 1/17/19 40m DX presentation entitled 40m DX
Propagation - the Daytime Corridor. A Solar Noon (SN) 40m DX Update was also
presented to SADXA on 11/1/19. This same presentation was given to Central
AZ DX Association on 10/3/20. 

This presentation predicted the possibility of SN 40m DX based on Daytime
Propagation theory near the terminator, direct observations at SN from
Tucson - Dec. 2018, and documented Daytime Solar Noon 40m DX Maps Paths
during Dec Solstice of 2018.  I defined a SN 40m Contact as being a QSO
within SN by +/- 1 Hr. 

The presentation pointed out that during the Dec. Solstice, the Northern
Solar Terminator is only about 2200 miles from Tucson at SN.  During SN,
almost the entire US is in the 40m DX enhanced propagation region near the
Terminator. This region is where the E layer and D absorption layers were
very weak, due to low elevation of the sun. This allows possible low loss F2
layer propagation within this region on 40m. 2019 was predicated to be
especially fruitful for  40m DAY DX, due to Low Sun Spot numbers of 0, and
very low Solar Flux. (Absolute Minimum ionization of E and D layers)

 

Solar Noon 40m DX Become Reality at SADXA

In Dec. 2019, 40m SN DX prediction became a reality from Tucson, when W6XI
and W7EXG (both with Yagi antennas) made many EU 40m CW Contacts, some
within just several minutes of SN.  Many more DX stations were heard. Wes,
N7WS also documented hearing 40m CW SN DX on a 40m wire inverted vee at 45
feet - facing EU. 

 

WSPR Documentation of SN 40m DX

SADXA member Darrel, AA7FV further participated by documenting Dec. 2019 40m
SN DX with 40m WSPR plots between Tucson and other parts of the world at SN
+/- 1 Hr. Darrel created a fascinating Movie showing the 40m SN DX paths
developing as a function of time. 

INVITATION TO PARTICIPATE - 2022 Dec Solstice 40m SN DX

Between now and the following 3 weeks, it may still be possible to hear, or
work 40m SN DX, most likely on CW.  Our 2019 experience showed the CW
Contest Days may be best. See CW Contests below.  [Contest Stations are up
Late at Night on 40m chasing DX during our SN. (Tip tnx to Jerry W6XI)]

*  Croatian CW Contest: 1400Z, Dec 18 to 1400Z, Dec 19 (Several QSOs in this
contest)

*Gedebage World Wide CW Contest: 1200Z, Dec 25 to 1159Z, Dec 26

FT8/4 40m SN DX Challenge

I also want to extend a challenge to the FT8/4 Crowd. Be the first to work
40m SN DX on FT8/4. This mode should have a decided advantage over CW for
40m SN DX - so they say!!!  This Year might be a real test? 

 

PROGNOSIS:

40m SN DX will likely never be as good as Dec Solstice in 2019, until
another 11 years.  The current (12/14/21) Sun Spot Number is 12, and Solar
Flux is 80. This suggests higher D absorption loss per hop and higher E
layer ionization, preventing initial F2 layer hops. While these indices are
higher, they may still allow some 40m SN DX. 

 

Below are Solar Indices for some following days

NOTE: Dec 19-26 and after Jan 1st may be most promising. DEC 21st was Best
40m SN DX Day in 2019 due to Contest. 

Date   / Flux / A index /  Kp index

13 Dec 2021     80  8     3

14 Dec 2021     80  5     2

15 Dec 2021     82  12  4

16 Dec 2021     84  10  3

17 Dec 2021     84  10  3

18 Dec 2021     84  8     3

19 Dec 2021     84  5     2

20 Dec 2021     84  5     2

21 Dec 2021     84  5     2

22 Dec 2021     82  5     2

23 Dec 2021     82  5     2

24 Dec 2021     82  5     2

25 Dec 2021     82  5     2

26 Dec 2021     82  5     2

27 Dec 2021     82  15  5

28 Dec 2021     80  18  5

29 Dec 2021     78  12  4

30 Dec 2021     78  8     3

01 Jan 2022      78  8     3

02 Jan 2022      78  5     2

03 Jan 2022      78  5     2

04 Jan 2022      80  5     2

05 Jan 2022      80  5     2

06 Jan 2022      80  5     2

07 Jan 2022      80  5     2

08 Jan 2022      80  5     2

More Tips

Our experience in 2019 during the Dec Solstice 40m SN DX was some days were
Nothing Heard - Nada - while other days in between inactive days - were
active.  Listen every day. You should 1st hear the East Coast working EU
just before EU favors AZ. 

To date, no 40m SN DX has been heard on a 40m inverted Vee at 27 feet,
although East Coast Stations have been heard working EU .

Give 40m SN DX a try!

73's

Bill W7EXG